From 0840a90d943bcde2fbfeabd3c256236eed2273cd Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Tue, 16 Oct 2007 23:27:22 -0700
Subject: [PATCH] exec: simplify ->sighand switching
There is no any reason to do recalc_sigpending() after changing ->sighand.
To begin with, recalc_sigpending() does not take ->sighand into account.
This means we don't need to take newsighand->siglock while changing sighands.
rcu_assign_pointer() provides a necessary barrier, and if another process
reads the new ->sighand it should either take tasklist_lock or it should use
lock_task_sighand() which has a corresponding smp_read_barrier_depends().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/exec.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 59c0038baa4f..7f325df5e014 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -916,12 +916,7 @@ no_thread_group:
write_lock_irq(&tasklist_lock);
spin_lock(&oldsighand->siglock);
- spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
-
rcu_assign_pointer(tsk->sighand, newsighand);
- recalc_sigpending();
-
- spin_unlock(&newsighand->siglock);
spin_unlock(&oldsighand->siglock);
write_unlock_irq(&tasklist_lock);
@@ -931,12 +926,11 @@ no_thread_group:
BUG_ON(!thread_group_leader(tsk));
return 0;
}
-
+
/*
* These functions flushes out all traces of the currently running executable
* so that a new one can be started
*/
-
static void flush_old_files(struct files_struct * files)
{
long j = -1;
--
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