linux-kernel - Re: [PATCH] drm/msm: Improve exception handling in msm_gpu_crashstate

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Message-ID: <56a615b6-9881-ff01-fa0f-8ea070fc03e7@web.de>
Date:   Fri, 12 Jun 2020 09:36:09 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Bernard Zhao <bernard@...o.com>, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        opensource.kernel@...o.com
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>
Subject: Re: [PATCH] drm/msm: Improve exception handling in
 msm_gpu_crashstate_capture()

> Function msm_gpu_crashstate_capture maybe called for several
> times, and then the state->bos is a potential memleak. Also
> the state->pos maybe alloc failed, but now without any handle.
> This change is to fix some potential memleak and add error
> handle when alloc failed.

I suggest to improve the provided information.
How do you think about a wording variant like the following?

   The function “msm_gpu_crashstate_capture” can be called multiple times.
   The members “comm”, “cmd” and “bos” of the data structure “msm_gpu_state”
   are reassigned with pointers according to dynamic memory allocations
   if the preprocessor symbol “CONFIG_DEV_COREDUMP” was defined.
   But the function “kfree” was not called for them before.

   Thus add missing actions.
   * Release previous objects.
   * Use further null pointer checks.
   * Complete the corresponding exception handling.

Would you like to add the tag “Fixes” to the commit message?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?id=b791d1bdf9212d944d749a5c7ff6febdba241771#n183

…
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -366,8 +366,11 @@  static void msm_gpu_crashstate_capture(struct msm_gpu *gpu,
>  			if (!should_dump(submit, submit->cmd[i].idx))
>  				nr++;
>
> +		kfree(state->bos);
>  		state->bos = kcalloc(nr,
>  			sizeof(struct msm_gpu_state_bo), GFP_KERNEL);
> +		if (!state->bos)
> +			return;
…

Will there be a need to reconsider the indentation for function call parameters
in such source files?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=b791d1bdf9212d944d749a5c7ff6febdba241771#n93

Regards,
Markus