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Commit 0840a90d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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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: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2b47c361

fs/exec.c

+1 −7
Original line number Diff line number Diff line
@@ -916,12 +916,7 @@ static int de_thread(struct task_struct *tsk) 


		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);
@@ -936,7 +931,6 @@ static int de_thread(struct task_struct *tsk) 
 * 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;