linux-kernel - Re: [RFC][PATCH v3 13/33] timers: drm: Use timer_shutdown

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Date:   Fri, 4 Nov 2022 08:48:28 +0000
From:   Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
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>,
        Guenter Roeck <linux@...ck-us.net>,
        Anna-Maria Gleixner <anna-maria@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Noralf Trønnes <noralf@...nnes.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org
Subject: Re: [RFC][PATCH v3 13/33] timers: drm: Use timer_shutdown_sync()
 before freeing timer


Hi,

On 04/11/2022 05:41, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
> 
> Before a timer is freed, timer_shutdown_sync() must be called.
> 
> Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home/
> 
> Cc: "Noralf Trønnes" <noralf@...nnes.org>
> Cc: David Airlie <airlied@...il.com>
> Cc: Daniel Vetter <daniel@...ll.ch>
> Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: intel-gfx@...ts.freedesktop.org
> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
> ---
>   drivers/gpu/drm/gud/gud_pipe.c       | 2 +-
>   drivers/gpu/drm/i915/i915_sw_fence.c | 2 +-

If it stays all DRM drivers in one patch then I guess it needs to go via 
drm-misc, which for i915 would be okay I think in this case since patch 
is extremely unlikely to clash with anything. Or split it up per driver 
and then we can handle it in drm-intel-next once core functionality is in.

We do however have some more calls to del_timer_sync, where freeing is 
perhaps not immediately next to the site in code, but things definitely 
get freed like on module unload. Would we need to convert all of them to 
avoid some, presumably new, warnings?

Regards,

Tvrtko

>   2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c
> index 7c6dc2bcd14a..08429bdd57cf 100644
> --- a/drivers/gpu/drm/gud/gud_pipe.c
> +++ b/drivers/gpu/drm/gud/gud_pipe.c
> @@ -272,7 +272,7 @@ static int gud_usb_bulk(struct gud_device *gdrm, size_t len)
>   
>   	usb_sg_wait(&ctx.sgr);
>   
> -	if (!del_timer_sync(&ctx.timer))
> +	if (!timer_shutdown_sync(&ctx.timer))
>   		ret = -ETIMEDOUT;
>   	else if (ctx.sgr.status < 0)
>   		ret = ctx.sgr.status;
> diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
> index 6fc0d1b89690..bfaa9a67dc35 100644
> --- a/drivers/gpu/drm/i915/i915_sw_fence.c
> +++ b/drivers/gpu/drm/i915/i915_sw_fence.c
> @@ -465,7 +465,7 @@ static void irq_i915_sw_fence_work(struct irq_work *wrk)
>   	struct i915_sw_dma_fence_cb_timer *cb =
>   		container_of(wrk, typeof(*cb), work);
>   
> -	del_timer_sync(&cb->timer);
> +	timer_shutdown_sync(&cb->timer);
>   	dma_fence_put(cb->dma);
>   
>   	kfree_rcu(cb, rcu);