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Date: Sat, 5 Nov 2022 17:45:42 -0400
From: Steven Rostedt <rostedt@goodmis.org>
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Subject: Re: [Bridge] [PATCH v4a 00/38] timers: Use timer_shutdown*() before
 freeing timers
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>, linux-staging@lists.linux.dev, linux-doc@vger.kernel.org, alsa-devel@alsa-project.org, dri-devel@lists.freedesktop.org, Thomas Gleixner <tglx@linutronix.de>, linux-leds@vger.kernel.org, drbd-dev@lists.linbit.com, linux-s390@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-scsi@vger.kernel.org, linux-sh@vger.kernel.org, linux-atm-general@lists.sourceforge.net, linux-afs@lists.infradead.org, lvs-devel@vger.kernel.org, linux-acpi@vger.kernel.org, coreteam@netfilter.org, intel-wired-lan@lists.osuosl.org, linux-input@vger.kernel.org, tipc-discussion@lists.sourceforge.net, linux-ext4@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>, linux-media@vger.kernel.org, bridge@lists.linux-foundation.org, linux-pm@vger.kernel.org, intel-gfx@lists.freedesktop.org, rcu@vger.kernel.org, cgroups@vger.kernel.org, openipmi-developer@lists.sourceforge.net, Anna-Maria Gleixner <anna-maria@linutronix.de>, linux-edac@vger.kernel.org, linux-block@vger.kernel.org, linux-nfs@vger.kernel.org, linux-parisc@vger.kernel.org, Stephen Boyd <sboyd@kernel.org>, netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org, netfilter-devel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, linaro-mm-sig@lists.linaro.org

On Sat, 5 Nov 2022 14:13:14 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> And trying "when != ptr->timer" actually does the right thing in that
> it gets rid of the case where the timer is modified outside of the
> del_timer() case, *but* it also causes odd other changes to the
> output.
> 
> Look at what it generates for that
> 
>    drivers/media/usb/pvrusb2/pvrusb2-hdw.c
> 
> file, which finds a lot of triggers with the "when !=  ptr->timer",
> but only does one without it.

I added an expression, and it appears to work:

At least for this case.

@@
expression E;
identifier ptr, timer, rfield, slab;
@@
(
-       del_timer(&ptr->timer);
+       timer_shutdown(&ptr->timer);
|
-       del_timer_sync(&ptr->timer);
+       timer_shutdown_sync(&ptr->timer);
)
  ... when != ptr->timer.function = E;
(
        kfree_rcu(ptr, rfield);
|
        kmem_cache_free(slab, ptr);
|
        kfree(ptr);
)

Now I need to add return and goto cases here.

-- Steve