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Merge patch series "exit: change the release_task() paths to call flush_sigqueue() lockless"

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Oleg Nesterov <oleg@redhat.com> says:

Change the release_task() paths to call flush_sigqueue() lockless.

* patches from https://lore.kernel.org/r/20250206152244.GA14609@redhat.com:
  exit: kill the pointless __exit_signal()->clear_tsk_thread_flag(TIF_SIGPENDING)
  exit: change the release_task() paths to call flush_sigqueue() lockless

Link: https://lore.kernel.org/r/20250206152244.GA14609@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-02-07 11:21:02 +01:00
parent 2014c95afe 43966114b4
commit 33be3ffd30
1 changed files with 11 additions and 9 deletions
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kernel/exit.c
+11 -9
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@@ -200,20 +200,12 @@ static void __exit_signal(struct task_struct *tsk)
__unhash_process(tsk, group_dead);
write_sequnlock(&sig->stats_lock);
/*
* Do this under ->siglock, we can race with another thread
* doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
*/
flush_sigqueue(&tsk->pending);
tsk->sighand = NULL;
spin_unlock(&sighand->siglock);
__cleanup_sighand(sighand);
clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
if (group_dead) {
flush_sigqueue(&sig->shared_pending);
if (group_dead)
tty_kref_put(tty);
}
}
static void delayed_put_task_struct(struct rcu_head *rhp)
@@ -279,6 +271,16 @@ repeat:
proc_flush_pid(thread_pid);
put_pid(thread_pid);
release_thread(p);
/*
* This task was already removed from the process/thread/pid lists
* and lock_task_sighand(p) can't succeed. Nobody else can touch
* ->pending or, if group dead, signal->shared_pending. We can call
* flush_sigqueue() lockless.
*/
flush_sigqueue(&p->pending);
if (thread_group_leader(p))
flush_sigqueue(&p->signal->shared_pending);
put_task_struct_rcu_user(p);
p = leader;