[PATCH 1/2] drm/i915/dmabuf: fix broken build

[Matthew Auld]

On Wed, 27 Oct 2021 at 15:54, Lucas De Marchi <lucas.demarchi at intel.com> wrote:
>
> On Wed, Oct 27, 2021 at 08:57:48AM +0100, Matthew Auld wrote:
> >On Thu, 21 Oct 2021 at 13:54, Matthew Auld <matthew.auld at intel.com> wrote:
> >>
> >> wbinvd_on_all_cpus() is only defined on x86 it seems, plus we need to
> >> include asm/smp.h here.
> >>
> >> Reported-by: kernel test robot <lkp at intel.com>
> >> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> >> Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> >
> >Jani, would it make sense to cherry-pick this to -fixes? The offending
> >commit is in drm-next, and there have been a few reports around this.
> >
> >Fixes: a035154da45d ("drm/i915/dmabuf: add paranoid flush-on-acquire")
> >
> >
> >> ---
> >>  drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 7 +++++++
> >>  1 file changed, 7 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> >> index 1adcd8e02d29..a45d0ec2c5b6 100644
> >> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> >> @@ -12,6 +12,13 @@
> >>  #include "i915_gem_object.h"
> >>  #include "i915_scatterlist.h"
> >>
> >> +#if defined(CONFIG_X86)
> >> +#include <asm/smp.h>
> >> +#else
> >> +#define wbinvd_on_all_cpus() \
> >> +       pr_warn(DRIVER_NAME ": Missing cache flush in %s\n", __func__)
>
>
> not sure I understand why this is a fix. Sure, it's true, but right now
> this file can't be built on any other arch.
>
> For clflush, wbind, etc, I'd rather change the code to use things from
> drm_cache rather than ifdef it out locally. This is
> "Reported-by: kernel test robot <lkp at intel.com>", but what's the error?

I guess it depends on the kernel config, but it reported:
error: implicit declaration of function 'wbinvd_on_all_cpus'

AFAIK it's the missing <asm/smp.h>, the CONFIG_X86 thing is just for
good measure.

I didn't spot anything in drm_cache which just offers a simple wrapper
for wbinvd?

>
> Lucas De Marchi
>
> >> +#endif
> >> +
> >>  I915_SELFTEST_DECLARE(static bool force_different_devices;)
> >>
> >>  static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf)
> >> --
> >> 2.26.3
> >>