From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v4a 00/38] timers: Use timer_shutdown*() before freeing
 timers
Date: Sat, 5 Nov 2022 17:45:42 -0400
Message-ID: <20221105174542.21bd7e86@rorschach.local.home>
References: <20221105060024.598488967@goodmis.org>
        <CAHk-=wi95dGkg7DiuOZ27gGW+mxJipn9ykB6LHB-HrbbLG6OMQ@mail.gmail.com>
        <20221105123642.596371c7@rorschach.local.home>
        <Y2bPlllkHo5DUmLY@zx2c4.com>
        <CAHk-=wjkkomrdcrAxxFijs-Lih6vHze+A2TgM+v7-Z7ZkXT+WA@mail.gmail.com>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Return-path: <linux-acpi-owner@vger.kernel.org>
In-Reply-To: <CAHk-=wjkkomrdcrAxxFijs-Lih6vHze+A2TgM+v7-Z7ZkXT+WA@mail.gmail.com>
List-ID: <cgroups.vger.kernel.org>
Content-Type: text/plain; charset="us-ascii"
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>, linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>, Stephen Boyd <sboyd@kernel.org>, Guenter Roeck <linux@roeck-us.net>, Anna-Maria Gleixner <anna-maria@linutronix.de>, Andrew Morton <akpm@linux-foundation.org>, rcu@vger.kernel.org, linux-doc@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-edac@vger.kernel.org, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-acpi@vger.kernel.org, linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org, linux-pm@vger.kernel.org, drbd-dev@lists.linbit.com, linux-bluetooth@vger.kernel.org, openipmi-developer@lists.sourceforge.net, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, intel-gfx

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