[PATCH v2 1/2] proc: Use PIDTYPE_TGID in next_tgid

Eric W. Biederman
2020-04-23T19:42:22Z

Combine the pid_task and thes test has_group_leader_pid into a single
dereference by using pid_task(PIDTYPE_TGID).

This makes the code simpler and proof against needing to even think
about any shenanigans that de_thread might get up to.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/proc/base.c | 16 ++--------------
1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 2868bff1a142..a48b4d4056a9 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3360,20 +3360,8 @@ static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter ite
pid = find_ge_pid(iter.tgid, ns);
if (pid) {
iter.tgid = pid_nr_ns(pid, ns);
- iter.task = pid_task(pid, PIDTYPE_PID);
- /* What we to know is if the pid we have find is the
- * pid of a thread_group_leader. Testing for task
- * being a thread_group_leader is the obvious thing
- * todo but there is a window when it fails, due to
- * the pid transfer logic in de_thread.
- *
- * So we perform the straight forward test of seeing
- * if the pid we have found is the pid of a thread
- * group leader, and don't worry if the task we have
- * found doesn't happen to be a thread group leader.
- * As we don't care in the case of readdir.
- */
- if (!iter.task || !has_group_leader_pid(iter.task)) {
+ iter.task = pid_task(pid, PIDTYPE_TGID);
+ if (!iter.task) {
iter.tgid += 1;
goto retry;
}
--
2.20.1