Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=46f382d2b69d2221086b823f0dbc8f32c027cac2
Commit: 46f382d2b69d2221086b823f0dbc8f32c027cac2
Parent: d36174bc2bce0372693a9cfbdef8b2689c9982cb
Author: Oleg Nesterov <[EMAIL PROTECTED]>
AuthorDate: Fri Feb 8 04:19:19 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Feb 8 09:22:28 2008 -0800
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 <[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]>
---
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 b91f473..f84d532 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)
-
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