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author | Paul E. McKenney <paul.mckenney@linaro.org> | 2011-07-19 03:25:36 -0700 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-07-20 11:04:54 -0700 |
commit | a841796f11c90d53dbac773be56b04fbee8af272 (patch) | |
tree | 9401a53faddecc7c1644565d0e22630028f82bca /Documentation/serial/n_gsm.txt | |
parent | ec433f0c51527426989ea8a38a856d810d739414 (diff) |
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 'Documentation/serial/n_gsm.txt')
0 files changed, 0 insertions, 0 deletions