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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2008-02-08 04:19:19 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-08 09:22:28 -0800 |
| commit | 46f382d2b69d2221086b823f0dbc8f32c027cac2 (patch) | |
| tree | bc71bbdd7f158aea817ef08f9cf13ac515d3776f /include/linux/pid.h | |
| parent | d36174bc2bce0372693a9cfbdef8b2689c9982cb (diff) | |
| download | linux-46f382d2b69d2221086b823f0dbc8f32c027cac2.tar.gz linux-46f382d2b69d2221086b823f0dbc8f32c027cac2.tar.bz2 linux-46f382d2b69d2221086b823f0dbc8f32c027cac2.zip | |
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>
Diffstat (limited to 'include/linux/pid.h')
| -rw-r--r-- | include/linux/pid.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h index b91f4732dc1b..f84d532b5d23 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -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) |