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| author | Peter Zijlstra | 2013-09-17 09:30:55 +0200 |
|---|---|---|
| committer | Ingo Molnar | 2013-09-25 13:53:08 +0200 |
| commit | b021fe3e25094fbec22d0eff846d2adeee1b9736 (patch) | |
| tree | 6193cc7952f980625e9f77c76f650fb2a7844071 /kernel/rcutree.c | |
| parent | x86: Use asm goto to implement better modify_and_test() functions (diff) | |
| download | kernel-qcow2-linux-b021fe3e25094fbec22d0eff846d2adeee1b9736.tar.gz kernel-qcow2-linux-b021fe3e25094fbec22d0eff846d2adeee1b9736.tar.xz kernel-qcow2-linux-b021fe3e25094fbec22d0eff846d2adeee1b9736.zip | |
sched, rcu: Make RCU use resched_cpu()
We're going to deprecate and remove set_need_resched() for it will do
the wrong thing. Make an exception for RCU and allow it to use
resched_cpu() which will do the right thing.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-2eywnacjl1nllctl1nszqa5w@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 32618b3fe4e6..1dc9f3604ad8 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -898,6 +898,12 @@ static void print_other_cpu_stall(struct rcu_state *rsp) force_quiescent_state(rsp); /* Kick them all. */ } +/* + * This function really isn't for public consumption, but RCU is special in + * that context switches can allow the state machine to make progress. + */ +extern void resched_cpu(int cpu); + static void print_cpu_stall(struct rcu_state *rsp) { int cpu; @@ -927,7 +933,14 @@ static void print_cpu_stall(struct rcu_state *rsp) 3 * rcu_jiffies_till_stall_check() + 3; raw_spin_unlock_irqrestore(&rnp->lock, flags); - set_need_resched(); /* kick ourselves to get things going. */ + /* + * Attempt to revive the RCU machinery by forcing a context switch. + * + * A context switch would normally allow the RCU state machine to make + * progress and it could be we're stuck in kernel space without context + * switches for an entirely unreasonable amount of time. + */ + resched_cpu(smp_processor_id()); } static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) |