From a841796f11c90d53dbac773be56b04fbee8af272 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 19 Jul 2011 03:25:36 -0700 Subject: [PATCH] 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-format-patch failed