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

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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 <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Davide Libenzi <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Cc: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Oleg Nesterov authored and Linus Torvalds committed 2008-02-08 09:22:28 -08:00
1 parent d36174bc2b
commit 46f382d2b6
1 file changed
+6
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include/linux/pid.h
+6
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@@ -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)