Commit 46f382d2 authored Feb 08, 2008 by Oleg Nesterov Committed by Linus Torvalds Feb 08, 2008

uglify while_each_pid_task() to make sure we don't count the execing pricess twice



There is a window when de_thread() switches the leader and drops
tasklist_lock.  In that window do_each_pid_task(PIDTYPE_PID) finds both new
and old leaders.

The problem is pretty much theoretical and probably can be ignored.  Currently
the only users of do_each_pid_task(PIDTYPE_PID) are send_sigio/send_sigurg, so
they can send the signal to the same process twice.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d36174bc

include/linux/pid.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -152,7 +152,13 @@ pid_t pid_vnr(struct pid *pid);
		hlist_for_each_entry_rcu((task), pos___, \
		&pid->tasks[type], pids[type].node) {

		/*
		* Both old and new leaders may be attached to
		* the same pid in the middle of de_thread().
		*/
		#define while_each_pid_task(pid, type, task) \
		if (type == PIDTYPE_PID) \
		break; \
		} \
		} while (0)

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