The patch titled
workqueue: don't clear cwq->thread until it exits
has been removed from the -mm tree. Its filename was
workqueue-dont-clear-cwq-thread-until-it-exits.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: workqueue: don't clear cwq->thread until it exits
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Pointed out by Srivatsa Vaddagiri.
cleanup_workqueue_thread() sets cwq->thread = NULL and does kthread_stop().
This breaks the "if (cwq->thread == current)" logic in flush_cpu_workqueue()
and leads to deadlock.
Kill the thead first, then clear cwq->thread. workqueue_mutex protects us
from create_workqueue_thread() so we don't need cwq->lock.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Srivatsa Vaddagiri <vatsa@xxxxxxxxxx>
Cc: "Pallipadi, Venkatesh" <venkatesh.pallipadi@xxxxxxxxx>
Cc: Gautham shenoy <ego@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/workqueue.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff -puN kernel/workqueue.c~workqueue-dont-clear-cwq-thread-until-it-exits kernel/workqueue.c
--- a/kernel/workqueue.c~workqueue-dont-clear-cwq-thread-until-it-exits
+++ a/kernel/workqueue.c
@@ -625,17 +625,12 @@ EXPORT_SYMBOL_GPL(__create_workqueue);
static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)
{
- struct cpu_workqueue_struct *cwq;
- unsigned long flags;
- struct task_struct *p;
+ struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
- cwq = per_cpu_ptr(wq->cpu_wq, cpu);
- spin_lock_irqsave(&cwq->lock, flags);
- p = cwq->thread;
- cwq->thread = NULL;
- spin_unlock_irqrestore(&cwq->lock, flags);
- if (p)
- kthread_stop(p);
+ if (cwq->thread) {
+ kthread_stop(cwq->thread);
+ cwq->thread = NULL;
+ }
}
/**
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
freezer-read-pf_borrowed_mm-in-a-nonracy-way.patch
freezer-close-theoretical-race-between-refrigerator-and-thaw_tasks.patch
freezer-remove-pf_nofreeze-from-rcutorture-thread.patch
freezer-remove-pf_nofreeze-from-bluetooth-threads.patch
freezer-add-try_to_freeze-calls-to-all-kernel-threads.patch
freezer-fix-vfork-problem.patch
freezer-take-kernel_execve-into-consideration.patch
nlmclnt_recovery-dont-use-clone_sighand.patch
fix-kthread_create-vs-freezer-theoretical-race.patch
fix-pf_nofreeze-and-freezeable-race-2.patch
freezer-document-task_lock-in-thaw_process.patch
move-frozen_process-to-kernel-power-processc.patch
separate-freezer-from-pm-code-rev-2.patch
introduce-freezer-flags-rev-2.patch
libata-core-convert-to-use-cancel_rearming_delayed_work.patch
clone-flag-clone_parent_tidptr-leaves-invalid-results-in-memory.patch
getrusage-fill-ru_inblock-and-ru_oublock-fields-if-possible.patch
dont-init-pgrp-and-__session-in-init_signals.patch
-
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