lkml.org 
[lkml]   [2021]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[GIT PULL] workqueue fixes for v5.15-rc6
Hello, Linus.

One patch to add a missing __printf and the other to enable deferred
printing for debug dumps to avoid deadlocks when triggered from some
contexts (e.g. console drivers).

Thanks.

The following changes since commit 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f:

Linux 5.15-rc1 (2021-09-12 16:28:37 -0700)

are available in the Git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-5.15-fixes

for you to fetch changes up to 57116ce17b04fde2fe30f0859df69d8dbe5809f6:

workqueue: fix state-dump console deadlock (2021-10-11 06:50:28 -1000)

----------------------------------------------------------------
Johan Hovold (1):
workqueue: fix state-dump console deadlock

Rolf Eike Beer (1):
workqueue: annotate alloc_workqueue() as printf

include/linux/workqueue.h | 5 ++---
kernel/workqueue.c | 18 ++++++++++++++++--
2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 2ebef6b1a3d6..74d3c1efd9bb 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -399,9 +399,8 @@ extern struct workqueue_struct *system_freezable_power_efficient_wq;
* RETURNS:
* Pointer to the allocated workqueue on success, %NULL on failure.
*/
-struct workqueue_struct *alloc_workqueue(const char *fmt,
- unsigned int flags,
- int max_active, ...);
+__printf(1, 4) struct workqueue_struct *
+alloc_workqueue(const char *fmt, unsigned int flags, int max_active, ...);

/**
* alloc_ordered_workqueue - allocate an ordered workqueue
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 33a6b4a2443d..1b3eb1e9531f 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4830,8 +4830,16 @@ void show_workqueue_state(void)

for_each_pwq(pwq, wq) {
raw_spin_lock_irqsave(&pwq->pool->lock, flags);
- if (pwq->nr_active || !list_empty(&pwq->inactive_works))
+ if (pwq->nr_active || !list_empty(&pwq->inactive_works)) {
+ /*
+ * Defer printing to avoid deadlocks in console
+ * drivers that queue work while holding locks
+ * also taken in their write paths.
+ */
+ printk_deferred_enter();
show_pwq(pwq);
+ printk_deferred_exit();
+ }
raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
/*
* We could be printing a lot from atomic context, e.g.
@@ -4849,7 +4857,12 @@ void show_workqueue_state(void)
raw_spin_lock_irqsave(&pool->lock, flags);
if (pool->nr_workers == pool->nr_idle)
goto next_pool;
-
+ /*
+ * Defer printing to avoid deadlocks in console drivers that
+ * queue work while holding locks also taken in their write
+ * paths.
+ */
+ printk_deferred_enter();
pr_info("pool %d:", pool->id);
pr_cont_pool_info(pool);
pr_cont(" hung=%us workers=%d",
@@ -4864,6 +4877,7 @@ void show_workqueue_state(void)
first = false;
}
pr_cont("\n");
+ printk_deferred_exit();
next_pool:
raw_spin_unlock_irqrestore(&pool->lock, flags);
/*
\
 
 \ /
  Last update: 2021-10-12 00:01    [W:0.040 / U:0.348 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site