linux-kernel - [RFC][PATCH 3/5] ia64: Catch up with new sighand action spinlock

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Date:	Tue,  5 Apr 2011 20:21:48 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Tejun Heo <tj@...nel.org>, Oleg Nesterov <oleg@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"H. Peter Anvin" <hpa@...or.com>,
	Matt Fleming <matt.fleming@...ux.intel.com>
Subject: [RFC][PATCH 3/5] ia64: Catch up with new sighand action spinlock

From: Matt Fleming <matt.fleming@...ux.intel.com>

Also delete the comment that says holding siglock might not be
necessary - it is, parts of signal code require that the handlers for
a sighand do not change.

Signed-off-by: Matt Fleming <matt.fleming@...ux.intel.com>
---
 arch/ia64/kernel/signal.c |   13 ++-----------
 1 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/arch/ia64/kernel/signal.c b/arch/ia64/kernel/signal.c
index 7bdafc8..d3b37c4 100644
--- a/arch/ia64/kernel/signal.c
+++ b/arch/ia64/kernel/signal.c
@@ -308,18 +308,9 @@ force_sigsegv_info (int sig, void __user *addr)
 	struct siginfo si;
 
 	if (sig == SIGSEGV) {
-		/*
-		 * Acquiring siglock around the sa_handler-update is almost
-		 * certainly overkill, but this isn't a
-		 * performance-critical path and I'd rather play it safe
-		 * here than having to debug a nasty race if and when
-		 * something changes in kernel/signal.c that would make it
-		 * no longer safe to modify sa_handler without holding the
-		 * lock.
-		 */
-		spin_lock_irqsave(&current->sighand->siglock, flags);
+		write_lock_irqsave(&current->sighand->action_lock, flags);
 		current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
-		spin_unlock_irqrestore(&current->sighand->siglock, flags);
+		write_unlock_irqrestore(&current->sighand->action_lock, flags);
 	}
 	si.si_signo = SIGSEGV;
 	si.si_errno = 0;
-- 
1.7.4

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