The patch titled
simplify/fix first_tid()
has been removed from the -mm tree. Its filename is
simplify-fix-first_tid.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: simplify/fix first_tid()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
first_tid:
/* If nr exceeds the number of threads there is nothing todo */
if (nr) {
if (nr >= get_nr_threads(leader))
goto done;
}
This is not reliable: sub-threads can exit after this check, so the
'for' loop below can overlap and proc_task_readdir() can return an
already filldir'ed dirents.
for (; pos && pid_alive(pos); pos = next_thread(pos)) {
if (--nr > 0)
continue;
Off-by-one error, will return 'leader' when nr == 1.
This patch tries to fix these problems and simplify the code.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/proc/base.c | 38 +++++++++++++++++---------------------
1 file changed, 17 insertions(+), 21 deletions(-)
diff -puN fs/proc/base.c~simplify-fix-first_tid fs/proc/base.c
--- a/fs/proc/base.c~simplify-fix-first_tid
+++ a/fs/proc/base.c
@@ -2227,38 +2227,34 @@ int proc_pid_readdir(struct file * filp,
static struct task_struct *first_tid(struct task_struct *leader,
int tid, int nr)
{
- struct task_struct *pos = NULL;
+ struct task_struct *pos;
rcu_read_lock();
/* Attempt to start with the pid of a thread */
if (tid && (nr > 0)) {
pos = find_task_by_pid(tid);
- if (pos && (pos->group_leader != leader))
- pos = NULL;
- if (pos)
- nr = 0;
+ if (pos && (pos->group_leader == leader))
+ goto found;
}
/* If nr exceeds the number of threads there is nothing todo */
- if (nr) {
- if (nr >= get_nr_threads(leader))
- goto done;
- }
+ pos = NULL;
+ if (nr && nr >= get_nr_threads(leader))
+ goto out;
- /* If we haven't found our starting place yet start with the
- * leader and walk nr threads forward.
+ /* If we haven't found our starting place yet start
+ * with the leader and walk nr threads forward.
*/
- if (!pos && (nr >= 0))
- pos = leader;
-
- for (; pos && pid_alive(pos); pos = next_thread(pos)) {
- if (--nr > 0)
- continue;
- get_task_struct(pos);
- goto done;
+ for (pos = leader; nr > 0; --nr) {
+ pos = next_thread(pos);
+ if (pos == leader) {
+ pos = NULL;
+ goto out;
+ }
}
- pos = NULL;
-done:
+found:
+ get_task_struct(pos);
+out:
rcu_read_unlock();
return pos;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
sched-uninline-task_rq_lock.patch
-
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