From: "Paul E. McKenney" <[email protected]> In theory, synchronize_sched() requires a read-side critical section to order against. In practice, preemption can be thought of as being disabled across every machine instruction. So this commit removes the redundant preempt_disable() from rcu_note_voluntary_context_switch().
Reported-by: Lai Jiangshan <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> --- include/linux/rcupdate.h | 2 -- 1 file changed, 2 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index f504f797c9c8..ed6e3e2e0089 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -326,10 +326,8 @@ static inline void rcu_user_hooks_switch(struct task_struct *prev, extern struct srcu_struct tasks_rcu_exit_srcu; #define rcu_note_voluntary_context_switch(t) \ do { \ - preempt_disable(); /* Exclude synchronize_sched(); */ \ if (ACCESS_ONCE((t)->rcu_tasks_holdout)) \ ACCESS_ONCE((t)->rcu_tasks_holdout) = 0; \ - preempt_enable(); \ } while (0) #else /* #ifdef CONFIG_TASKS_RCU */ #define TASKS_RCU(x) do { } while (0) -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
