Commit 913292c9 authored Jan 24, 2020 by Madhuparna Bhowmik Committed by Christian Brauner Jan 26, 2020

sched.h: Annotate sighand_struct with __rcu

This patch fixes the following sparse errors by annotating the
sighand_struct with __rcu

kernel/fork.c:1511:9: error: incompatible types in comparison expression
kernel/exit.c:100:19: error: incompatible types in comparison expression
kernel/signal.c:1370:27: error: incompatible types in comparison expression

This fix introduces the following sparse error in signal.c due to
checking the sighand pointer without rcu primitives:

kernel/signal.c:1386:21: error: incompatible types in comparison expression

This new sparse error is also fixed in this patch.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20200124045908.26389-1-madhuparnabhowmik10@gmail.com

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

parent 873dfd78

include/linux/sched.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -917,7 +917,7 @@ struct task_struct {

		/* Signal handlers: */
		struct signal_struct *signal;
		struct sighand_struct *sighand;
		struct sighand_struct __rcu *sighand;
		sigset_t blocked;
		sigset_t real_blocked;
		/* Restored if set_restore_sigmask() was used: */

kernel/signal.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1383,7 +1383,7 @@ struct sighand_struct __lock_task_sighand(struct task_struct tsk,
		* must see ->sighand == NULL.
		*/
		spin_lock_irqsave(&sighand->siglock, *flags);
		if (likely(sighand == tsk->sighand))
		if (likely(sighand == rcu_access_pointer(tsk->sighand)))
		break;
		spin_unlock_irqrestore(&sighand->siglock, *flags);
		}

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