diff options
Diffstat (limited to 'kernel/locking/lockdep.c')
| -rw-r--r-- | kernel/locking/lockdep.c | 1204 |
1 files changed, 909 insertions, 295 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index c0e31bfee25c..e36e652d996f 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -58,6 +58,10 @@ #define CREATE_TRACE_POINTS #include <trace/events/lock.h> +#ifdef CONFIG_LOCKDEP_CROSSRELEASE +#include <linux/slab.h> +#endif + #ifdef CONFIG_PROVE_LOCKING int prove_locking = 1; module_param(prove_locking, int, 0644); @@ -344,14 +348,12 @@ EXPORT_SYMBOL(lockdep_on); #if VERBOSE # define HARDIRQ_VERBOSE 1 # define SOFTIRQ_VERBOSE 1 -# define RECLAIM_VERBOSE 1 #else # define HARDIRQ_VERBOSE 0 # define SOFTIRQ_VERBOSE 0 -# define RECLAIM_VERBOSE 0 #endif -#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE +#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE /* * Quick filtering for interesting events: */ @@ -726,6 +728,18 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL); } +#ifdef CONFIG_LOCKDEP_CROSSRELEASE +static void cross_init(struct lockdep_map *lock, int cross); +static int cross_lock(struct lockdep_map *lock); +static int lock_acquire_crosslock(struct held_lock *hlock); +static int lock_release_crosslock(struct lockdep_map *lock); +#else +static inline void cross_init(struct lockdep_map *lock, int cross) {} +static inline int cross_lock(struct lockdep_map *lock) { return 0; } +static inline int lock_acquire_crosslock(struct held_lock *hlock) { return 2; } +static inline int lock_release_crosslock(struct lockdep_map *lock) { return 2; } +#endif + /* * Register a lock's class in the hash-table, if the class is not present * yet. Otherwise we look it up. We cache the result in the lock object @@ -1125,22 +1139,41 @@ print_circular_lock_scenario(struct held_lock *src, printk(KERN_CONT "\n\n"); } - printk(" Possible unsafe locking scenario:\n\n"); - printk(" CPU0 CPU1\n"); - printk(" ---- ----\n"); - printk(" lock("); - __print_lock_name(target); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(parent); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(target); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(source); - printk(KERN_CONT ");\n"); - printk("\n *** DEADLOCK ***\n\n"); + if (cross_lock(tgt->instance)) { + printk(" Possible unsafe locking scenario by crosslock:\n\n"); + printk(" CPU0 CPU1\n"); + printk(" ---- ----\n"); + printk(" lock("); + __print_lock_name(parent); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(target); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(source); + printk(KERN_CONT ");\n"); + printk(" unlock("); + __print_lock_name(target); + printk(KERN_CONT ");\n"); + printk("\n *** DEADLOCK ***\n\n"); + } else { + printk(" Possible unsafe locking scenario:\n\n"); + printk(" CPU0 CPU1\n"); + printk(" ---- ----\n"); + printk(" lock("); + __print_lock_name(target); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(parent); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(target); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(source); + printk(KERN_CONT ");\n"); + printk("\n *** DEADLOCK ***\n\n"); + } } /* @@ -1157,18 +1190,23 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth, if (debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("======================================================\n"); pr_warn("WARNING: possible circular locking dependency detected\n"); print_kernel_ident(); pr_warn("------------------------------------------------------\n"); - printk("%s/%d is trying to acquire lock:\n", + pr_warn("%s/%d is trying to acquire lock:\n", curr->comm, task_pid_nr(curr)); print_lock(check_src); - printk("\nbut task is already holding lock:\n"); + + if (cross_lock(check_tgt->instance)) + pr_warn("\nbut now in release context of a crosslock acquired at the following:\n"); + else + pr_warn("\nbut task is already holding lock:\n"); + print_lock(check_tgt); - printk("\nwhich lock already depends on the new lock.\n\n"); - printk("\nthe existing dependency chain (in reverse order) is:\n"); + pr_warn("\nwhich lock already depends on the new lock.\n\n"); + pr_warn("\nthe existing dependency chain (in reverse order) is:\n"); print_circular_bug_entry(entry, depth); @@ -1183,7 +1221,8 @@ static inline int class_equal(struct lock_list *entry, void *data) static noinline int print_circular_bug(struct lock_list *this, struct lock_list *target, struct held_lock *check_src, - struct held_lock *check_tgt) + struct held_lock *check_tgt, + struct stack_trace *trace) { struct task_struct *curr = current; struct lock_list *parent; @@ -1193,7 +1232,9 @@ static noinline int print_circular_bug(struct lock_list *this, if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; - if (!save_trace(&this->trace)) + if (cross_lock(check_tgt->instance)) + this->trace = *trace; + else if (!save_trace(&this->trace)) return 0; depth = get_lock_depth(target); @@ -1309,6 +1350,19 @@ check_noncircular(struct lock_list *root, struct lock_class *target, return result; } +static noinline int +check_redundant(struct lock_list *root, struct lock_class *target, + struct lock_list **target_entry) +{ + int result; + + debug_atomic_inc(nr_redundant_checks); + + result = __bfs_forwards(root, target, class_equal, target_entry); + + return result; +} + #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) /* * Forwards and backwards subgraph searching, for the purposes of @@ -1495,13 +1549,13 @@ print_bad_irq_dependency(struct task_struct *curr, if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("=====================================================\n"); pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", irqclass, irqclass); print_kernel_ident(); pr_warn("-----------------------------------------------------\n"); - printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", + pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", curr->comm, task_pid_nr(curr), curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, @@ -1509,46 +1563,46 @@ print_bad_irq_dependency(struct task_struct *curr, curr->softirqs_enabled); print_lock(next); - printk("\nand this task is already holding:\n"); + pr_warn("\nand this task is already holding:\n"); print_lock(prev); - printk("which would create a new lock dependency:\n"); + pr_warn("which would create a new lock dependency:\n"); print_lock_name(hlock_class(prev)); - printk(KERN_CONT " ->"); + pr_cont(" ->"); print_lock_name(hlock_class(next)); - printk(KERN_CONT "\n"); + pr_cont("\n"); - printk("\nbut this new dependency connects a %s-irq-safe lock:\n", + pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", irqclass); print_lock_name(backwards_entry->class); - printk("\n... which became %s-irq-safe at:\n", irqclass); + pr_warn("\n... which became %s-irq-safe at:\n", irqclass); print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); - printk("\nto a %s-irq-unsafe lock:\n", irqclass); + pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); print_lock_name(forwards_entry->class); - printk("\n... which became %s-irq-unsafe at:\n", irqclass); - printk("..."); + pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); + pr_warn("..."); print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); - printk("\nother info that might help us debug this:\n\n"); + pr_warn("\nother info that might help us debug this:\n\n"); print_irq_lock_scenario(backwards_entry, forwards_entry, hlock_class(prev), hlock_class(next)); lockdep_print_held_locks(curr); - printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); + pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); if (!save_trace(&prev_root->trace)) return 0; print_shortest_lock_dependencies(backwards_entry, prev_root); - printk("\nthe dependencies between the lock to be acquired"); - printk(" and %s-irq-unsafe lock:\n", irqclass); + pr_warn("\nthe dependencies between the lock to be acquired"); + pr_warn(" and %s-irq-unsafe lock:\n", irqclass); if (!save_trace(&next_root->trace)) return 0; print_shortest_lock_dependencies(forwards_entry, next_root); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; @@ -1724,22 +1778,22 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("============================================\n"); pr_warn("WARNING: possible recursive locking detected\n"); print_kernel_ident(); pr_warn("--------------------------------------------\n"); - printk("%s/%d is trying to acquire lock:\n", + pr_warn("%s/%d is trying to acquire lock:\n", curr->comm, task_pid_nr(curr)); print_lock(next); - printk("\nbut task is already holding lock:\n"); + pr_warn("\nbut task is already holding lock:\n"); print_lock(prev); - printk("\nother info that might help us debug this:\n"); + pr_warn("\nother info that might help us debug this:\n"); print_deadlock_scenario(next, prev); lockdep_print_held_locks(curr); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; @@ -1784,6 +1838,9 @@ check_deadlock(struct task_struct *curr, struct held_lock *next, if (nest) return 2; + if (cross_lock(prev->instance)) + continue; + return print_deadlock_bug(curr, prev, next); } return 1; @@ -1813,20 +1870,13 @@ check_deadlock(struct task_struct *curr, struct held_lock *next, */ static int check_prev_add(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next, int distance, int *stack_saved) + struct held_lock *next, int distance, struct stack_trace *trace, + int (*save)(struct stack_trace *trace)) { + struct lock_list *uninitialized_var(target_entry); struct lock_list *entry; - int ret; struct lock_list this; - struct lock_list *uninitialized_var(target_entry); - /* - * Static variable, serialized by the graph_lock(). - * - * We use this static variable to save the stack trace in case - * we call into this function multiple times due to encountering - * trylocks in the held lock stack. - */ - static struct stack_trace trace; + int ret; /* * Prove that the new <prev> -> <next> dependency would not @@ -1840,8 +1890,17 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, this.class = hlock_class(next); this.parent = NULL; ret = check_noncircular(&this, hlock_class(prev), &target_entry); - if (unlikely(!ret)) - return print_circular_bug(&this, target_entry, next, prev); + if (unlikely(!ret)) { + if (!trace->entries) { + /* + * If @save fails here, the printing might trigger + * a WARN but because of the !nr_entries it should + * not do bad things. + */ + save(trace); + } + return print_circular_bug(&this, target_entry, next, prev, trace); + } else if (unlikely(ret < 0)) return print_bfs_bug(ret); @@ -1870,15 +1929,26 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, if (entry->class == hlock_class(next)) { if (distance == 1) entry->distance = 1; - return 2; + return 1; } } - if (!*stack_saved) { - if (!save_trace(&trace)) - return 0; - *stack_saved = 1; + /* + * Is the <prev> -> <next> link redundant? + */ + this.class = hlock_class(prev); + this.parent = NULL; + ret = check_redundant(&this, hlock_class(next), &target_entry); + if (!ret) { + debug_atomic_inc(nr_redundant); + return 2; } + if (ret < 0) + return print_bfs_bug(ret); + + + if (!trace->entries && !save(trace)) + return 0; /* * Ok, all validations passed, add the new lock @@ -1886,33 +1956,18 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, */ ret = add_lock_to_list(hlock_class(next), &hlock_class(prev)->locks_after, - next->acquire_ip, distance, &trace); + next->acquire_ip, distance, trace); if (!ret) return 0; ret = add_lock_to_list(hlock_class(prev), &hlock_class(next)->locks_before, - next->acquire_ip, distance, &trace); + next->acquire_ip, distance, trace); if (!ret) return 0; - /* - * Debugging printouts: - */ - if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { - /* We drop graph lock, so another thread can overwrite trace. */ - *stack_saved = 0; - graph_unlock(); - printk("\n new dependency: "); - print_lock_name(hlock_class(prev)); - printk(KERN_CONT " => "); - print_lock_name(hlock_class(next)); - printk(KERN_CONT "\n"); - dump_stack(); - return graph_lock(); - } - return 1; + return 2; } /* @@ -1925,8 +1980,13 @@ static int check_prevs_add(struct task_struct *curr, struct held_lock *next) { int depth = curr->lockdep_depth; - int stack_saved = 0; struct held_lock *hlock; + struct stack_trace trace = { + .nr_entries = 0, + .max_entries = 0, + .entries = NULL, + .skip = 0, + }; /* * Debugging checks. @@ -1947,21 +2007,29 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next) int distance = curr->lockdep_depth - depth + 1; hlock = curr->held_locks + depth - 1; /* - * Only non-recursive-read entries get new dependencies - * added: + * Only non-crosslock entries get new dependencies added. + * Crosslock entries will be added by commit later: */ - if (hlock->read != 2 && hlock->check) { - if (!check_prev_add(curr, hlock, next, - distance, &stack_saved)) - return 0; + if (!cross_lock(hlock->instance)) { /* - * Stop after the first non-trylock entry, - * as non-trylock entries have added their - * own direct dependencies already, so this - * lock is connected to them indirectly: + * Only non-recursive-read entries get new dependencies + * added: */ - if (!hlock->trylock) - break; + if (hlock->read != 2 && hlock->check) { + int ret = check_prev_add(curr, hlock, next, + distance, &trace, save_trace); + if (!ret) + return 0; + + /* + * Stop after the first non-trylock entry, + * as non-trylock entries have added their + * own direct dependencies already, so this + * lock is connected to them indirectly: + */ + if (!hlock->trylock) + break; + } } depth--; /* @@ -2074,21 +2142,21 @@ static void print_collision(struct task_struct *curr, struct held_lock *hlock_next, struct lock_chain *chain) { - printk("\n"); + pr_warn("\n"); pr_warn("============================\n"); pr_warn("WARNING: chain_key collision\n"); print_kernel_ident(); pr_warn("----------------------------\n"); - printk("%s/%d: ", current->comm, task_pid_nr(current)); - printk("Hash chain already cached but the contents don't match!\n"); + pr_warn("%s/%d: ", current->comm, task_pid_nr(current)); + pr_warn("Hash chain already cached but the contents don't match!\n"); - printk("Held locks:"); + pr_warn("Held locks:"); print_chain_keys_held_locks(curr, hlock_next); - printk("Locks in cached chain:"); + pr_warn("Locks in cached chain:"); print_chain_keys_chain(chain); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); } #endif @@ -2126,19 +2194,26 @@ static int check_no_collision(struct task_struct *curr, } /* - * Look up a dependency chain. If the key is not present yet then - * add it and return 1 - in this case the new dependency chain is - * validated. If the key is already hashed, return 0. - * (On return with 1 graph_lock is held.) + * This is for building a chain between just two different classes, + * instead of adding a new hlock upon current, which is done by + * add_chain_cache(). + * + * This can be called in any context with two classes, while + * add_chain_cache() must be done within the lock owener's context + * since it uses hlock which might be racy in another context. */ -static inline int lookup_chain_cache(struct task_struct *curr, - struct held_lock *hlock, - u64 chain_key) +static inline int add_chain_cache_classes(unsigned int prev, + unsigned int next, + unsigned int irq_context, + u64 chain_key) { - struct lock_class *class = hlock_class(hlock); struct hlist_head *hash_head = chainhashentry(chain_key); struct lock_chain *chain; - int i, j; + + /* + * Allocate a new chain entry from the static array, and add + * it to the hash: + */ /* * We might need to take the graph lock, ensure we've got IRQs @@ -2147,43 +2222,76 @@ static inline int lookup_chain_cache(struct task_struct *curr, */ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return 0; + + if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { + if (!debug_locks_off_graph_unlock()) + return 0; + + print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); + dump_stack(); + return 0; + } + + chain = lock_chains + nr_lock_chains++; + chain->chain_key = chain_key; + chain->irq_context = irq_context; + chain->depth = 2; + if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { + chain->base = nr_chain_hlocks; + nr_chain_hlocks += chain->depth; + chain_hlocks[chain->base] = prev - 1; + chain_hlocks[chain->base + 1] = next -1; + } +#ifdef CONFIG_DEBUG_LOCKDEP /* - * We can walk it lock-free, because entries only get added - * to the hash: + * Important for check_no_collision(). */ - hlist_for_each_entry_rcu(chain, hash_head, entry) { - if (chain->chain_key == chain_key) { -cache_hit: - debug_atomic_inc(chain_lookup_hits); - if (!check_no_collision(curr, hlock, chain)) - return 0; - - if (very_verbose(class)) - printk("\nhash chain already cached, key: " - "%016Lx tail class: [%p] %s\n", - (unsigned long long)chain_key, - class->key, class->name); + else { + if (!debug_locks_off_graph_unlock()) return 0; - } + + print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); + dump_stack(); + return 0; } - if (very_verbose(class)) - printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", - (unsigned long long)chain_key, class->key, class->name); +#endif + + hlist_add_head_rcu(&chain->entry, hash_head); + debug_atomic_inc(chain_lookup_misses); + inc_chains(); + + return 1; +} + +/* + * Adds a dependency chain into chain hashtable. And must be called with + * graph_lock held. + * + * Return 0 if fail, and graph_lock is released. + * Return 1 if succeed, with graph_lock held. + */ +static inline int add_chain_cache(struct task_struct *curr, + struct held_lock *hlock, + u64 chain_key) +{ + struct lock_class *class = hlock_class(hlock); + struct hlist_head *hash_head = chainhashentry(chain_key); + struct lock_chain *chain; + int i, j; + /* * Allocate a new chain entry from the static array, and add * it to the hash: */ - if (!graph_lock()) - return 0; + /* - * We have to walk the chain again locked - to avoid duplicates: + * We might need to take the graph lock, ensure we've got IRQs + * disabled to make this an IRQ-safe lock.. for recursion reasons + * lockdep won't complain about its own locking errors. */ - hlist_for_each_entry(chain, hash_head, entry) { - if (chain->chain_key == chain_key) { - graph_unlock(); - goto cache_hit; - } - } + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return 0; + if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { if (!debug_locks_off_graph_unlock()) return 0; @@ -2235,6 +2343,78 @@ cache_hit: return 1; } +/* + * Look up a dependency chain. + */ +static inline struct lock_chain *lookup_chain_cache(u64 chain_key) +{ + struct hlist_head *hash_head = chainhashentry(chain_key); + struct lock_chain *chain; + + /* + * We can walk it lock-free, because entries only get added + * to the hash: + */ + hlist_for_each_entry_rcu(chain, hash_head, entry) { + if (chain->chain_key == chain_key) { + debug_atomic_inc(chain_lookup_hits); + return chain; + } + } + return NULL; +} + +/* + * If the key is not present yet in dependency chain cache then + * add it and return 1 - in this case the new dependency chain is + * validated. If the key is already hashed, return 0. + * (On return with 1 graph_lock is held.) + */ +static inline int lookup_chain_cache_add(struct task_struct *curr, + struct held_lock *hlock, + u64 chain_key) +{ + struct lock_class *class = hlock_class(hlock); + struct lock_chain *chain = lookup_chain_cache(chain_key); + + if (chain) { +cache_hit: + if (!check_no_collision(curr, hlock, chain)) + return 0; + + if (very_verbose(class)) { + printk("\nhash chain already cached, key: " + "%016Lx tail class: [%p] %s\n", + (unsigned long long)chain_key, + class->key, class->name); + } + + return 0; + } + + if (very_verbose(class)) { + printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", + (unsigned long long)chain_key, class->key, class->name); + } + + if (!graph_lock()) + return 0; + + /* + * We have to walk the chain again locked - to avoid duplicates: + */ + chain = lookup_chain_cache(chain_key); + if (chain) { + graph_unlock(); + goto cache_hit; + } + + if (!add_chain_cache(curr, hlock, chain_key)) + return 0; + + return 1; +} + static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, struct held_lock *hlock, int chain_head, u64 chain_key) { @@ -2245,11 +2425,11 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, * * We look up the chain_key and do the O(N^2) check and update of * the dependencies only if this is a new dependency chain. - * (If lookup_chain_cache() returns with 1 it acquires + * (If lookup_chain_cache_add() return with 1 it acquires * graph_lock for us) */ if (!hlock->trylock && hlock->check && - lookup_chain_cache(curr, hlock, chain_key)) { + lookup_chain_cache_add(curr, hlock, chain_key)) { /* * Check whether last held lock: * @@ -2277,14 +2457,17 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, * Add dependency only if this lock is not the head * of the chain, and if it's not a secondary read-lock: */ - if (!chain_head && ret != 2) + if (!chain_head && ret != 2) { if (!check_prevs_add(curr, hlock)) return 0; + } + graph_unlock(); - } else - /* after lookup_chain_cache(): */ + } else { + /* after lookup_chain_cache_add(): */ if (unlikely(!debug_locks)) return 0; + } return 1; } @@ -2373,16 +2556,16 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this, if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("================================\n"); pr_warn("WARNING: inconsistent lock state\n"); print_kernel_ident(); pr_warn("--------------------------------\n"); - printk("inconsistent {%s} -> {%s} usage.\n", + pr_warn("inconsistent {%s} -> {%s} usage.\n", usage_str[prev_bit], usage_str[new_bit]); - printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", + pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", curr->comm, task_pid_nr(curr), trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, @@ -2390,16 +2573,16 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this, trace_softirqs_enabled(curr)); print_lock(this); - printk("{%s} state was registered at:\n", usage_str[prev_bit]); + pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]); print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); print_irqtrace_events(curr); - printk("\nother info that might help us debug this:\n"); + pr_warn("\nother info that might help us debug this:\n"); print_usage_bug_scenario(this); lockdep_print_held_locks(curr); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; @@ -2438,28 +2621,28 @@ print_irq_inversion_bug(struct task_struct *curr, if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("========================================================\n"); pr_warn("WARNING: possible irq lock inversion dependency detected\n"); print_kernel_ident(); pr_warn("--------------------------------------------------------\n"); - printk("%s/%d just changed the state of lock:\n", + pr_warn("%s/%d just changed the state of lock:\n", curr->comm, task_pid_nr(curr)); print_lock(this); if (forwards) - printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass); + pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); else - printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); + pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); print_lock_name(other->class); - printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); + pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); - printk("\nother info that might help us debug this:\n"); + pr_warn("\nother info that might help us debug this:\n"); /* Find a middle lock (if one exists) */ depth = get_lock_depth(other); do { if (depth == 0 && (entry != root)) { - printk("lockdep:%s bad path found in chain graph\n", __func__); + pr_warn("lockdep:%s bad path found in chain graph\n", __func__); break; } middle = entry; @@ -2475,12 +2658,12 @@ print_irq_inversion_bug(struct task_struct *curr, lockdep_print_held_locks(curr); - printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); + pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); if (!save_trace(&root->trace)) return 0; print_shortest_lock_dependencies(other, root); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; @@ -2567,14 +2750,6 @@ static int SOFTIRQ_verbose(struct lock_class *class) return 0; } -static int RECLAIM_FS_verbose(struct lock_class *class) -{ -#if RECLAIM_VERBOSE - return class_filter(class); -#endif - return 0; -} - #define STRICT_READ_CHECKS 1 static int (*state_verbose_f[])(struct lock_class *class) = { @@ -2870,57 +3045,6 @@ void trace_softirqs_off(unsigned long ip) debug_atomic_inc(redundant_softirqs_off); } -static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags) -{ - struct task_struct *curr = current; - - if (unlikely(!debug_locks)) - return; - - gfp_mask = current_gfp_context(gfp_mask); - - /* no reclaim without waiting on it */ - if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) - return; - - /* this guy won't enter reclaim */ - if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) - return; - - /* We're only interested __GFP_FS allocations for now */ - if (!(gfp_mask & __GFP_FS) || (curr->flags & PF_MEMALLOC_NOFS)) - return; - - /* - * Oi! Can't be having __GFP_FS allocations with IRQs disabled. - */ - if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))) - return; - - /* Disable lockdep if explicitly requested */ - if (gfp_mask & __GFP_NOLOCKDEP) - return; - - mark_held_locks(curr, RECLAIM_FS); -} - -static void check_flags(unsigned long flags); - -void lockdep_trace_alloc(gfp_t gfp_mask) -{ - unsigned long flags; - - if (unlikely(current->lockdep_recursion)) - return; - - raw_local_irq_save(flags); - check_flags(flags); - current->lockdep_recursion = 1; - __lockdep_trace_alloc(gfp_mask, flags); - current->lockdep_recursion = 0; - raw_local_irq_restore(flags); -} - static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) { /* @@ -2966,22 +3090,6 @@ static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) } } - /* - * We reuse the irq context infrastructure more broadly as a general - * context checking code. This tests GFP_FS recursion (a lock taken - * during reclaim for a GFP_FS allocation is held over a GFP_FS - * allocation). - */ - if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) { - if (hlock->read) { - if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ)) - return 0; - } else { - if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS)) - return 0; - } - } - return 1; } @@ -3040,10 +3148,6 @@ static inline int separate_irq_context(struct task_struct *curr, return 0; } -void lockdep_trace_alloc(gfp_t gfp_mask) -{ -} - #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ /* @@ -3116,7 +3220,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, /* * Initialize a lock instance's lock-class mapping info: */ -void lockdep_init_map(struct lockdep_map *lock, const char *name, +static void __lockdep_init_map(struct lockdep_map *lock, const char *name, struct lock_class_key *key, int subclass) { int i; @@ -3174,8 +3278,25 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name, raw_local_irq_restore(flags); } } + +void lockdep_init_map(struct lockdep_map *lock, const char *name, + struct lock_class_key *key, int subclass) +{ + cross_init(lock, 0); + __lockdep_init_map(lock, name, key, subclass); +} EXPORT_SYMBOL_GPL(lockdep_init_map); +#ifdef CONFIG_LOCKDEP_CROSSRELEASE +void lockdep_init_map_crosslock(struct lockdep_map *lock, const char *name, + struct lock_class_key *key, int subclass) +{ + cross_init(lock, 1); + __lockdep_init_map(lock, name, key, subclass); +} +EXPORT_SYMBOL_GPL(lockdep_init_map_crosslock); +#endif + struct lock_class_key __lockdep_no_validate__; EXPORT_SYMBOL_GPL(__lockdep_no_validate__); @@ -3189,25 +3310,25 @@ print_lock_nested_lock_not_held(struct task_struct *curr, if (debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("==================================\n"); pr_warn("WARNING: Nested lock was not taken\n"); print_kernel_ident(); pr_warn("----------------------------------\n"); - printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); + pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); print_lock(hlock); - printk("\nbut this task is not holding:\n"); - printk("%s\n", hlock->nest_lock->name); + pr_warn("\nbut this task is not holding:\n"); + pr_warn("%s\n", hlock->nest_lock->name); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); - printk("\nother info that might help us debug this:\n"); + pr_warn("\nother info that might help us debug this:\n"); lockdep_print_held_locks(curr); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; @@ -3231,6 +3352,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, int chain_head = 0; int class_idx; u64 chain_key; + int ret; if (unlikely(!debug_locks)) return 0; @@ -3279,7 +3401,8 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, class_idx = class - lock_classes + 1; - if (depth) { + /* TODO: nest_lock is not implemented for crosslock yet. */ + if (depth && !cross_lock(lock)) { hlock = curr->held_locks + depth - 1; if (hlock->class_idx == class_idx && nest_lock) { if (hlock->references) { @@ -3367,6 +3490,14 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) return 0; + ret = lock_acquire_crosslock(hlock); + /* + * 2 means normal acquire operations are needed. Otherwise, it's + * ok just to return with '0:fail, 1:success'. + */ + if (ret != 2) + return ret; + curr->curr_chain_key = chain_key; curr->lockdep_depth++; check_chain_key(curr); @@ -3402,21 +3533,21 @@ print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock, if (debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("=====================================\n"); pr_warn("WARNING: bad unlock balance detected!\n"); print_kernel_ident(); pr_warn("-------------------------------------\n"); - printk("%s/%d is trying to release lock (", + pr_warn("%s/%d is trying to release lock (", curr->comm, task_pid_nr(curr)); print_lockdep_cache(lock); - printk(KERN_CONT ") at:\n"); + pr_cont(") at:\n"); print_ip_sym(ip); - printk("but there are no more locks to release!\n"); - printk("\nother info that might help us debug this:\n"); + pr_warn("but there are no more locks to release!\n"); + pr_warn("\nother info that might help us debug this:\n"); lockdep_print_held_locks(curr); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; @@ -3604,11 +3735,19 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) struct task_struct *curr = current; struct held_lock *hlock; unsigned int depth; - int i; + int ret, i; if (unlikely(!debug_locks)) return 0; + ret = lock_release_crosslock(lock); + /* + * 2 means normal release operations are needed. Otherwise, it's + * ok just to return with '0:fail, 1:success'. + */ + if (ret != 2) + return ret; + depth = curr->lockdep_depth; /* * So we're all set to release this lock.. wait what lock? We don't @@ -3952,18 +4091,6 @@ void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) } EXPORT_SYMBOL_GPL(lock_unpin_lock); -void lockdep_set_current_reclaim_state(gfp_t gfp_mask) -{ - current->lockdep_reclaim_gfp = current_gfp_context(gfp_mask); -} -EXPORT_SYMBOL_GPL(lockdep_set_current_reclaim_state); - -void lockdep_clear_current_reclaim_state(void) -{ - current->lockdep_reclaim_gfp = 0; -} -EXPORT_SYMBOL_GPL(lockdep_clear_current_reclaim_state); - #ifdef CONFIG_LOCK_STAT static int print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, @@ -3974,21 +4101,21 @@ print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, if (debug_locks_silent) return 0; - printk("\n"); + pr_warn("\n"); pr_warn("=================================\n"); pr_warn("WARNING: bad contention detected!\n"); print_kernel_ident(); pr_warn("---------------------------------\n"); - printk("%s/%d is trying to contend lock (", + pr_warn("%s/%d is trying to contend lock (", curr->comm, task_pid_nr(curr)); print_lockdep_cache(lock); - printk(KERN_CONT ") at:\n"); + pr_cont(") at:\n"); print_ip_sym(ip); - printk("but there are no locks held!\n"); - printk("\nother info that might help us debug this:\n"); + pr_warn("but there are no locks held!\n"); + pr_warn("\nother info that might help us debug this:\n"); lockdep_print_held_locks(curr); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; @@ -4318,17 +4445,17 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from, if (debug_locks_silent) return; - printk("\n"); + pr_warn("\n"); pr_warn("=========================\n"); pr_warn("WARNING: held lock freed!\n"); print_kernel_ident(); pr_warn("-------------------------\n"); - printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", + pr_warn("%s/%d is freeing memory %p-%p, with a lock still held there!\n", curr->comm, task_pid_nr(curr), mem_from, mem_to-1); print_lock(hlock); lockdep_print_held_locks(curr); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); } @@ -4376,14 +4503,14 @@ static void print_held_locks_bug(void) if (debug_locks_silent) return; - printk("\n"); + pr_warn("\n"); pr_warn("====================================\n"); pr_warn("WARNING: %s/%d still has locks held!\n", current->comm, task_pid_nr(current)); print_kernel_ident(); pr_warn("------------------------------------\n"); lockdep_print_held_locks(current); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); } @@ -4402,10 +4529,10 @@ void debug_show_all_locks(void) int unlock = 1; if (unlikely(!debug_locks)) { - printk("INFO: lockdep is turned off.\n"); + pr_warn("INFO: lockdep is turned off.\n"); return; } - printk("\nShowing all locks held in the system:\n"); + pr_warn("\nShowing all locks held in the system:\n"); /* * Here we try to get the tasklist_lock as hard as possible, @@ -4416,18 +4543,18 @@ void debug_show_all_locks(void) retry: if (!read_trylock(&tasklist_lock)) { if (count == 10) - printk("hm, tasklist_lock locked, retrying... "); + pr_warn("hm, tasklist_lock locked, retrying... "); if (count) { count--; - printk(" #%d", 10-count); + pr_cont(" #%d", 10-count); mdelay(200); goto retry; } - printk(" ignoring it.\n"); + pr_cont(" ignoring it.\n"); unlock = 0; } else { if (count != 10) - printk(KERN_CONT " locked it.\n"); + pr_cont(" locked it.\n"); } do_each_thread(g, p) { @@ -4445,7 +4572,7 @@ retry: unlock = 1; } while_each_thread(g, p); - printk("\n"); + pr_warn("\n"); pr_warn("=============================================\n\n"); if (unlock) @@ -4475,34 +4602,36 @@ asmlinkage __visible void lockdep_sys_exit(void) if (unlikely(curr->lockdep_depth)) { if (!debug_locks_off()) return; - printk("\n"); + pr_warn("\n"); pr_warn("================================================\n"); pr_warn("WARNING: lock held when returning to user space!\n"); print_kernel_ident(); pr_warn("------------------------------------------------\n"); - printk("%s/%d is leaving the kernel with locks still held!\n", + pr_warn("%s/%d is leaving the kernel with locks still held!\n", curr->comm, curr->pid); lockdep_print_held_locks(curr); } + + /* + * The lock history for each syscall should be independent. So wipe the + * slate clean on return to userspace. + */ + lockdep_invariant_state(false); } void lockdep_rcu_suspicious(const char *file, const int line, const char *s) { struct task_struct *curr = current; -#ifndef CONFIG_PROVE_RCU_REPEATEDLY - if (!debug_locks_off()) - return; -#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */ /* Note: the following can be executed concurrently, so be careful. */ - printk("\n"); + pr_warn("\n"); pr_warn("=============================\n"); pr_warn("WARNING: suspicious RCU usage\n"); print_kernel_ident(); pr_warn("-----------------------------\n"); - printk("%s:%d %s!\n", file, line, s); - printk("\nother info that might help us debug this:\n\n"); - printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n", + pr_warn("%s:%d %s!\n", file, line, s); + pr_warn("\nother info that might help us debug this:\n\n"); + pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n", !rcu_lockdep_current_cpu_online() ? "RCU used illegally from offline CPU!\n" : !rcu_is_watching() @@ -4529,10 +4658,495 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) * rcu_read_lock_bh() and so on from extended quiescent states. */ if (!rcu_is_watching()) - printk("RCU used illegally from extended quiescent state!\n"); + pr_warn("RCU used illegally from extended quiescent state!\n"); lockdep_print_held_locks(curr); - printk("\nstack backtrace:\n"); + pr_warn("\nstack backtrace:\n"); dump_stack(); } EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); + +#ifdef CONFIG_LOCKDEP_CROSSRELEASE + +/* + * Crossrelease works by recording a lock history for each thread and + * connecting those historic locks that were taken after the + * wait_for_completion() in the complete() context. + * + * Task-A Task-B + * + * mutex_lock(&A); + * mutex_unlock(&A); + * + * wait_for_completion(&C); + * lock_acquire_crosslock(); + * atomic_inc_return(&cross_gen_id); + * | + * | mutex_lock(&B); + * | mutex_unlock(&B); + * | + * | complete(&C); + * `-- lock_commit_crosslock(); + * + * Which will then add a dependency between B and C. + */ + +#define xhlock(i) (current->xhlocks[(i) % MAX_XHLOCKS_NR]) + +/* + * Whenever a crosslock is held, cross_gen_id will be increased. + */ +static atomic_t cross_gen_id; /* Can be wrapped */ + +/* + * Make an entry of the ring buffer invalid. + */ +static inline void invalidate_xhlock(struct hist_lock *xhlock) +{ + /* + * Normally, xhlock->hlock.instance must be !NULL. + */ + xhlock->hlock.instance = NULL; +} + +/* + * Lock history stacks; we have 2 nested lock history stacks: + * + * HARD(IRQ) + * SOFT(IRQ) + * + * The thing is that once we complete a HARD/SOFT IRQ the future task locks + * should not depend on any of the locks observed while running the IRQ. So + * what we do is rewind the history buffer and erase all our knowledge of that + * temporal event. + */ + +void crossrelease_hist_start(enum xhlock_context_t c) +{ + struct task_struct *cur = current; + + if (!cur->xhlocks) + return; + + cur->xhlock_idx_hist[c] = cur->xhlock_idx; + cur->hist_id_save[c] = cur->hist_id; +} + +void crossrelease_hist_end(enum xhlock_context_t c) +{ + struct task_struct *cur = current; + + if (cur->xhlocks) { + unsigned int idx = cur->xhlock_idx_hist[c]; + struct hist_lock *h = &xhlock(idx); + + cur->xhlock_idx = idx; + + /* Check if the ring was overwritten. */ + if (h->hist_id != cur->hist_id_save[c]) + invalidate_xhlock(h); + } +} + +/* + * lockdep_invariant_state() is used to annotate independence inside a task, to + * make one task look like multiple independent 'tasks'. + * + * Take for instance workqueues; each work is independent of the last. The + * completion of a future work does not depend on the completion of a past work + * (in general). Therefore we must not carry that (lock) dependency across + * works. + * + * This is true for many things; pretty much all kthreads fall into this + * pattern, where they have an invariant state and future completions do not + * depend on past completions. Its just that since they all have the 'same' + * form -- the kthread does the same over and over -- it doesn't typically + * matter. + * + * The same is true for system-calls, once a system call is completed (we've + * returned to userspace) the next system call does not depend on the lock + * history of the previous system call. + * + * They key property for independence, this invariant state, is that it must be + * a point where we hold no locks and have no history. Because if we were to + * hold locks, the restore at _end() would not necessarily recover it's history + * entry. Similarly, independence per-definition means it does not depend on + * prior state. + */ +void lockdep_invariant_state(bool force) +{ + /* + * We call this at an invariant point, no current state, no history. + * Verify the former, enforce the latter. + */ + WARN_ON_ONCE(!force && current->lockdep_depth); + invalidate_xhlock(&xhlock(current->xhlock_idx)); +} + +static int cross_lock(struct lockdep_map *lock) +{ + return lock ? lock->cross : 0; +} + +/* + * This is needed to decide the relationship between wrapable variables. + */ +static inline int before(unsigned int a, unsigned int b) +{ + return (int)(a - b) < 0; +} + +static inline struct lock_class *xhlock_class(struct hist_lock *xhlock) +{ + return hlock_class(&xhlock->hlock); +} + +static inline struct lock_class *xlock_class(struct cross_lock *xlock) +{ + return hlock_class(&xlock->hlock); +} + +/* + * Should we check a dependency with previous one? + */ +static inline int depend_before(struct held_lock *hlock) +{ + return hlock->read != 2 && hlock->check && !hlock->trylock; +} + +/* + * Should we check a dependency with next one? + */ +static inline int depend_after(struct held_lock *hlock) +{ + return hlock->read != 2 && hlock->check; +} + +/* + * Check if the xhlock is valid, which would be false if, + * + * 1. Has not used after initializaion yet. + * 2. Got invalidated. + * + * Remind hist_lock is implemented as a ring buffer. + */ +static inline int xhlock_valid(struct hist_lock *xhlock) +{ + /* + * xhlock->hlock.instance must be !NULL. + */ + return !!xhlock->hlock.instance; +} + +/* + * Record a hist_lock entry. + * + * Irq disable is only required. + */ +static void add_xhlock(struct held_lock *hlock) +{ + unsigned int idx = ++current->xhlock_idx; + struct hist_lock *xhlock = &xhlock(idx); + +#ifdef CONFIG_DEBUG_LOCKDEP + /* + * This can be done locklessly because they are all task-local + * state, we must however ensure IRQs are disabled. + */ + WARN_ON_ONCE(!irqs_disabled()); +#endif + + /* Initialize hist_lock's members */ + xhlock->hlock = *hlock; + xhlock->hist_id = ++current->hist_id; + + xhlock->trace.nr_entries = 0; + xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES; + xhlock->trace.entries = xhlock->trace_entries; + xhlock->trace.skip = 3; + save_stack_trace(&xhlock->trace); +} + +static inline int same_context_xhlock(struct hist_lock *xhlock) +{ + return xhlock->hlock.irq_context == task_irq_context(current); +} + +/* + * This should be lockless as far as possible because this would be + * called very frequently. + */ +static void check_add_xhlock(struct held_lock *hlock) +{ + /* + * Record a hist_lock, only in case that acquisitions ahead + * could depend on the held_lock. For example, if the held_lock + * is trylock then acquisitions ahead never depends on that. + * In that case, we don't need to record it. Just return. + */ + if (!current->xhlocks || !depend_before(hlock)) + return; + + add_xhlock(hlock); +} + +/* + * For crosslock. + */ +static int add_xlock(struct held_lock *hlock) +{ + struct cross_lock *xlock; + unsigned int gen_id; + + if (!graph_lock()) + return 0; + + xlock = &((struct lockdep_map_cross *)hlock->instance)->xlock; + + /* + * When acquisitions for a crosslock are overlapped, we use + * nr_acquire to perform commit for them, based on cross_gen_id + * of the first acquisition, which allows to add additional + * dependencies. + * + * Moreover, when no acquisition of a crosslock is in progress, + * we should not perform commit because the lock might not exist + * any more, which might cause incorrect memory access. So we + * have to track the number of acquisitions of a crosslock. + * + * depend_after() is necessary to initialize only the first + * valid xlock so that the xlock can be used on its commit. + */ + if (xlock->nr_acquire++ && depend_after(&xlock->hlock)) + goto unlock; + + gen_id = (unsigned int)atomic_inc_return(&cross_gen_id); + xlock->hlock = *hlock; + xlock->hlock.gen_id = gen_id; +unlock: + graph_unlock(); + return 1; +} + +/* + * Called for both normal and crosslock acquires. Normal locks will be + * pushed on the hist_lock queue. Cross locks will record state and + * stop regular lock_acquire() to avoid being placed on the held_lock + * stack. + * + * Return: 0 - failure; + * 1 - crosslock, done; + * 2 - normal lock, continue to held_lock[] ops. + */ +static int lock_acquire_crosslock(struct held_lock *hlock) +{ + /* + * CONTEXT 1 CONTEXT 2 + * --------- --------- + * lock A (cross) + * X = atomic_inc_return(&cross_gen_id) + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * Y = atomic_read_acquire(&cross_gen_id) + * lock B + * + * atomic_read_acquire() is for ordering between A and B, + * IOW, A happens before B, when CONTEXT 2 see Y >= X. + * + * Pairs with atomic_inc_return() in add_xlock(). + */ + hlock->gen_id = (unsigned int)atomic_read_acquire(&cross_gen_id); + + if (cross_lock(hlock->instance)) + return add_xlock(hlock); + + check_add_xhlock(hlock); + return 2; +} + +static int copy_trace(struct stack_trace *trace) +{ + unsigned long *buf = stack_trace + nr_stack_trace_entries; + unsigned int max_nr = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; + unsigned int nr = min(max_nr, trace->nr_entries); + + trace->nr_entries = nr; + memcpy(buf, trace->entries, nr * sizeof(trace->entries[0])); + trace->entries = buf; + nr_stack_trace_entries += nr; + + if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { + if (!debug_locks_off_graph_unlock()) + return 0; + + print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); + dump_stack(); + + return 0; + } + + return 1; +} + +static int commit_xhlock(struct cross_lock *xlock, struct hist_lock *xhlock) +{ + unsigned int xid, pid; + u64 chain_key; + + xid = xlock_class(xlock) - lock_classes; + chain_key = iterate_chain_key((u64)0, xid); + pid = xhlock_class(xhlock) - lock_classes; + chain_key = iterate_chain_key(chain_key, pid); + + if (lookup_chain_cache(chain_key)) + return 1; + + if (!add_chain_cache_classes(xid, pid, xhlock->hlock.irq_context, + chain_key)) + return 0; + + if (!check_prev_add(current, &xlock->hlock, &xhlock->hlock, 1, + &xhlock->trace, copy_trace)) + return 0; + + return 1; +} + +static void commit_xhlocks(struct cross_lock *xlock) +{ + unsigned int cur = current->xhlock_idx; + unsigned int prev_hist_id = xhlock(cur).hist_id; + unsigned int i; + + if (!graph_lock()) + return; + + if (xlock->nr_acquire) { + for (i = 0; i < MAX_XHLOCKS_NR; i++) { + struct hist_lock *xhlock = &xhlock(cur - i); + + if (!xhlock_valid(xhlock)) + break; + + if (before(xhlock->hlock.gen_id, xlock->hlock.gen_id)) + break; + + if (!same_context_xhlock(xhlock)) + break; + + /* + * Filter out the cases where the ring buffer was + * overwritten and the current entry has a bigger + * hist_id than the previous one, which is impossible + * otherwise: + */ + if (unlikely(before(prev_hist_id, xhlock->hist_id))) + break; + + prev_hist_id = xhlock->hist_id; + + /* + * commit_xhlock() returns 0 with graph_lock already + * released if fail. + */ + if (!commit_xhlock(xlock, xhlock)) + return; + } + } + + graph_unlock(); +} + +void lock_commit_crosslock(struct lockdep_map *lock) +{ + struct cross_lock *xlock; + unsigned long flags; + + if (unlikely(!debug_locks || current->lockdep_recursion)) + return; + + if (!current->xhlocks) + return; + + /* + * Do commit hist_locks with the cross_lock, only in case that + * the cross_lock could depend on acquisitions after that. + * + * For example, if the cross_lock does not have the 'check' flag + * then we don't need to check dependencies and commit for that. + * Just skip it. In that case, of course, the cross_lock does + * not depend on acquisitions ahead, either. + * + * WARNING: Don't do that in add_xlock() in advance. When an + * acquisition context is different from the commit context, + * invalid(skipped) cross_lock might be accessed. + */ + if (!depend_after(&((struct lockdep_map_cross *)lock)->xlock.hlock)) + return; + + raw_local_irq_save(flags); + check_flags(flags); + current->lockdep_recursion = 1; + xlock = &((struct lockdep_map_cross *)lock)->xlock; + commit_xhlocks(xlock); + current->lockdep_recursion = 0; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(lock_commit_crosslock); + +/* + * Return: 0 - failure; + * 1 - crosslock, done; + * 2 - normal lock, continue to held_lock[] ops. + */ +static int lock_release_crosslock(struct lockdep_map *lock) +{ + if (cross_lock(lock)) { + if (!graph_lock()) + return 0; + ((struct lockdep_map_cross *)lock)->xlock.nr_acquire--; + graph_unlock(); + return 1; + } + return 2; +} + +static void cross_init(struct lockdep_map *lock, int cross) +{ + if (cross) + ((struct lockdep_map_cross *)lock)->xlock.nr_acquire = 0; + + lock->cross = cross; + + /* + * Crossrelease assumes that the ring buffer size of xhlocks + * is aligned with power of 2. So force it on build. + */ + BUILD_BUG_ON(MAX_XHLOCKS_NR & (MAX_XHLOCKS_NR - 1)); +} + +void lockdep_init_task(struct task_struct *task) +{ + int i; + + task->xhlock_idx = UINT_MAX; + task->hist_id = 0; + + for (i = 0; i < XHLOCK_CTX_NR; i++) { + task->xhlock_idx_hist[i] = UINT_MAX; + task->hist_id_save[i] = 0; + } + + task->xhlocks = kzalloc(sizeof(struct hist_lock) * MAX_XHLOCKS_NR, + GFP_KERNEL); +} + +void lockdep_free_task(struct task_struct *task) +{ + if (task->xhlocks) { + void *tmp = task->xhlocks; + /* Diable crossrelease for current */ + task->xhlocks = NULL; + kfree(tmp); + } +} +#endif |