linux-kernel - Re: [RFC][PATCH v2 04/31] timers: block: Use del_timer

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Date:   Fri, 28 Oct 2022 08:11:50 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>,
        Philipp Reisner <philipp.reisner@...bit.com>,
        Lars Ellenberg <lars.ellenberg@...bit.com>,
        Christoph Böhmwalder 
        <christoph.boehmwalder@...bit.com>, Jens Axboe <axboe@...nel.dk>,
        drbd-dev@...ts.linbit.com, Tejun Heo <tj@...nel.org>,
        cgroups@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [RFC][PATCH v2 04/31] timers: block: Use del_timer_shutdown()
 before freeing timer

On 10/27/22 08:05, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
> 
> Before a timer is freed, del_timer_shutdown() must be called.
> 

I also had to add the following, as you had already suggested.

Just changing blk_sync_queue() was insufficient; I had to add the call from
blk_release_queue() because otherwise blk_sync_queue() was not always called.

Thanks,
Guenter

---
diff --git a/block/blk-core.c b/block/blk-core.c
index 17667159482e..69b1daa2e91a 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -227,7 +227,7 @@ const char *blk_status_to_str(blk_status_t status)
   */
  void blk_sync_queue(struct request_queue *q)
  {
-       del_timer_sync(&q->timeout);
+       del_timer_shutdown(&q->timeout);
         cancel_work_sync(&q->timeout_work);
  }
  EXPORT_SYMBOL(blk_sync_queue);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e71b3b43927c..12a1e46536ed 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -769,6 +769,8 @@ static void blk_release_queue(struct kobject *kobj)

         percpu_ref_exit(&q->q_usage_counter);

+       blk_sync_queue(q);
+
         if (q->poll_stat)
                 blk_stat_remove_callback(q, q->poll_cb);
         blk_stat_free_callback(q->poll_cb);