linux-kernel - Re: [Intel-gfx] [PATCH v3] drm: move allocation out of drm_get_format

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Date:   Wed, 9 Nov 2016 02:13:25 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Eric Engestrom <eric@...estrom.ch>
Cc:     linux-kernel@...r.kernel.org, David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org,
        Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Flora Cui <Flora.Cui@....com>,
        Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
        Tom St Denis <tom.stdenis@....com>,
        Chunming Zhou <David1.Zhou@....com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Sinclair Yeh <syeh@...are.com>,
        Xinliang Liu <z.liuxinliang@...ilicon.com>,
        Xinwei Kong <kong.kongxinwei@...ilicon.com>,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Vitaly Prosyak <vitaly.prosyak@....com>,
        Eric Engestrom <eric.engestrom@...tec.com>,
        Alexandre Demers <alexandre.f.demers@...il.com>,
        Jani Nikula <jani.nikula@...el.com>,
        intel-gfx@...ts.freedesktop.org, Emily Deng <Emily.Deng@....com>,
        Colin Ian King <colin.king@...onical.com>,
        Junwei Zhang <Jerry.Zhang@....com>,
        Michel Dänzer <michel.daenzer@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>
Subject: Re: [Intel-gfx] [PATCH v3] drm: move allocation out of
 drm_get_format_name()

On Wed, Nov 09, 2016 at 02:09:16AM +0100, Daniel Vetter wrote:
> On Wed, Nov 09, 2016 at 12:17:52AM +0000, Eric Engestrom wrote:
> > The function's behaviour was changed in 90844f00049e, without changing
> > its signature, causing people to keep using it the old way without
> > realising they were now leaking memory.
> > Rob Clark also noticed it was also allocating GFP_KERNEL memory in
> > atomic contexts, breaking them.
> > 
> > Instead of having to allocate GFP_ATOMIC memory and fixing the callers
> > to make them cleanup the memory afterwards, let's change the function's
> > signature by having the caller take care of the memory and passing it to
> > the function.
> > The new parameter is a single-field struct in order to enforce the size
> > of its buffer and help callers to correctly manage their memory.
> > 
> > Fixes: 90844f00049e ("drm: make drm_get_format_name thread-safe")
> > Cc: Rob Clark <robdclark@...il.com>
> > Cc: Christian König <christian.koenig@....com>
> > Acked-by: Christian König <christian.koenig@....com>
> > Acked-by: Rob Clark <robdclark@...il.com>
> > Acked-by: Sinclair Yeh <syeh@...are.com> (vmwgfx)
> > Reviewed-by: Jani Nikula <jani.nikula@...el.com>
> > Suggested-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > Signed-off-by: Eric Engestrom <eric@...estrom.ch>
> > ---
> > v3 - fix "Fixes" tag, replace it with an actual commit message
> >    - collect ack & r-b
> > 
> > v2 - use single-field struct instead of typedef to let the compiler
> >      enforce the type (Christian König)
> 
> Applied to drm-misc, thanks.

Well, had to drop it again since it didn't compile:


  CC [M]  drivers/gpu/drm/drm_blend.o
drivers/gpu/drm/drm_atomic.c: In function ‘drm_atomic_plane_print_state’:
drivers/gpu/drm/drm_atomic.c:920:5: error: too few arguments to function ‘drm_get_format_name’
     drm_get_format_name(fb->pixel_format));
     ^~~~~~~~~~~~~~~~~~~
In file included from ./include/drm/drmP.h:71:0,
                 from drivers/gpu/drm/drm_atomic.c:29:
./include/drm/drm_fourcc.h:65:7: note: declared here
 char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf);
       ^~~~~~~~~~~~~~~~~~~

Can you pls rebase onto drm-misc or linux-next or something?

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch