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| author | Paul E. McKenney | 2011-07-19 12:25:36 +0200 |
|---|---|---|
| committer | Paul E. McKenney | 2011-07-20 20:04:54 +0200 |
| commit | a841796f11c90d53dbac773be56b04fbee8af272 (patch) | |
| tree | 9401a53faddecc7c1644565d0e22630028f82bca /kernel/sched.c | |
| parent | softirq,rcu: Inform RCU of irq_exit() activity (diff) | |
| download | kernel-qcow2-linux-a841796f11c90d53dbac773be56b04fbee8af272.tar.gz kernel-qcow2-linux-a841796f11c90d53dbac773be56b04fbee8af272.tar.xz kernel-qcow2-linux-a841796f11c90d53dbac773be56b04fbee8af272.zip | |
signal: align __lock_task_sighand() irq disabling and RCU
The __lock_task_sighand() function calls rcu_read_lock() with interrupts
and preemption enabled, but later calls rcu_read_unlock() with interrupts
disabled. It is therefore possible that this RCU read-side critical
section will be preempted and later RCU priority boosted, which means that
rcu_read_unlock() will call rt_mutex_unlock() in order to deboost itself, but
with interrupts disabled. This results in lockdep splats, so this commit
nests the RCU read-side critical section within the interrupt-disabled
region of code. This prevents the RCU read-side critical section from
being preempted, and thus prevents the attempt to deboost with interrupts
disabled.
It is quite possible that a better long-term fix is to make rt_mutex_unlock()
disable irqs when acquiring the rt_mutex structure's ->wait_lock.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/sched.c')
0 files changed, 0 insertions, 0 deletions