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author | Oleg Nesterov <oleg@redhat.com> | 2013-07-04 02:08:31 +0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-04 03:08:03 +0400 |
commit | 8190773985141f063e1d6dc10200527c655abfb5 (patch) | |
tree | 5c148834f047748dfa2ce3500236b89656976567 /include/linux/pid.h | |
parent | 80628ca06c5d42929de6bc22c0a41589a834d151 (diff) | |
download | linux-8190773985141f063e1d6dc10200527c655abfb5.tar.xz |
kernel/fork.c:copy_process(): don't add the uninitialized child to thread/task/pid lists
copy_process() adds the new child to thread_group/init_task.tasks list and
then does attach_pid(child, PIDTYPE_PID). This means that the lockless
next_thread() or next_task() can see this thread with the wrong pid. Say,
"ls /proc/pid/task" can list the same inode twice.
We could move attach_pid(child, PIDTYPE_PID) up, but in this case
find_task_by_vpid() can find the new thread before it was fully
initialized.
And this is already true for PIDTYPE_PGID/PIDTYPE_SID, With this patch
copy_process() initializes child->pids[*].pid first, then calls
attach_pid() to insert the task into the pid->tasks list.
attach_pid() no longer need the "struct pid*" argument, it is always
called after pid_link->pid was already set.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Sergey Dyasly <dserrg@gmail.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, 2 insertions, 4 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h index a089a3c447fc..23705a53abba 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -86,11 +86,9 @@ extern struct task_struct *get_pid_task(struct pid *pid, enum pid_type); extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type); /* - * attach_pid() and detach_pid() must be called with the tasklist_lock - * write-held. + * these helpers must be called with the tasklist_lock write-held. */ -extern void attach_pid(struct task_struct *task, enum pid_type type, - struct pid *pid); +extern void attach_pid(struct task_struct *task, enum pid_type); extern void detach_pid(struct task_struct *task, enum pid_type); extern void change_pid(struct task_struct *task, enum pid_type, struct pid *pid); |