From: Paul E. McKenney Date: Tue, 19 Jul 2011 10:25:36 +0000 (-0700) Subject: signal: align __lock_task_sighand() irq disabling and RCU X-Git-Tag: v3.0~7^2^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a841796f11c90d53dbac773be56b04fbee8af272;p=pandora-kernel.git 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 Signed-off-by: Paul E. McKenney --- Reading git-diff-tree failed