Re: [Intel-gfx] [PATCH 14/21] drm/i915/gem: Return an error ptr from context_lookup

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Apr 29, 2021 at 10:29:51AM -0500, Jason Ekstrand wrote:
> On Thu, Apr 29, 2021 at 8:27 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> >
> > On Fri, Apr 23, 2021 at 05:31:24PM -0500, Jason Ekstrand wrote:
> > > We're about to start doing lazy context creation which means contexts
> > > get created in i915_gem_context_lookup and we may start having more
> > > errors than -ENOENT.
> > >
> > > Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
> > > ---
> > >  drivers/gpu/drm/i915/gem/i915_gem_context.c    | 12 ++++++------
> > >  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c |  4 ++--
> > >  drivers/gpu/drm/i915/i915_drv.h                |  2 +-
> > >  drivers/gpu/drm/i915/i915_perf.c               |  4 ++--
> > >  4 files changed, 11 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > index 3e883daab93bf..7929d5a8be449 100644
> > > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > @@ -2105,8 +2105,8 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
> > >       int ret = 0;
> > >
> > >       ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
> > > -     if (!ctx)
> > > -             return -ENOENT;
> > > +     if (IS_ERR(ctx))
> > > +             return PTR_ERR(ctx);
> > >
> > >       switch (args->param) {
> > >       case I915_CONTEXT_PARAM_GTT_SIZE:
> > > @@ -2174,8 +2174,8 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
> > >       int ret;
> > >
> > >       ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
> > > -     if (!ctx)
> > > -             return -ENOENT;
> > > +     if (IS_ERR(ctx))
> > > +             return PTR_ERR(ctx);
> > >
> > >       ret = ctx_setparam(file_priv, ctx, args);
> > >
> > > @@ -2194,8 +2194,8 @@ int i915_gem_context_reset_stats_ioctl(struct drm_device *dev,
> > >               return -EINVAL;
> > >
> > >       ctx = i915_gem_context_lookup(file->driver_priv, args->ctx_id);
> > > -     if (!ctx)
> > > -             return -ENOENT;
> > > +     if (IS_ERR(ctx))
> > > +             return PTR_ERR(ctx);
> > >
> > >       /*
> > >        * We opt for unserialised reads here. This may result in tearing
> > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> > > index 7024adcd5cf15..de14b26f3b2d5 100644
> > > --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> > > @@ -739,8 +739,8 @@ static int eb_select_context(struct i915_execbuffer *eb)
> > >       struct i915_gem_context *ctx;
> > >
> > >       ctx = i915_gem_context_lookup(eb->file->driver_priv, eb->args->rsvd1);
> > > -     if (unlikely(!ctx))
> > > -             return -ENOENT;
> > > +     if (unlikely(IS_ERR(ctx)))
> > > +             return PTR_ERR(ctx);
> > >
> > >       eb->gem_context = ctx;
> > >       if (rcu_access_pointer(ctx->vm))
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > > index 8571c5c1509a7..004ed0e59c999 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> >
> > I just realized that I think __i915_gem_context_lookup_rcu doesn't have
> > users anymore. Please make sure it's deleted.
> 
> I deleted it in "drm/i915: Stop manually RCU banging in reset_stats_ioctl"

Indeed that's the case, so looks all fine. The benefits of reviewing
patches one-by-one :-/
-Daniel

> 
> 
> > > @@ -1851,7 +1851,7 @@ i915_gem_context_lookup(struct drm_i915_file_private *file_priv, u32 id)
> > >               ctx = NULL;
> > >       rcu_read_unlock();
> > >
> > > -     return ctx;
> > > +     return ctx ? ctx : ERR_PTR(-ENOENT);
> > >  }
> > >
> > >  /* i915_gem_evict.c */
> > > diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> > > index 85ad62dbabfab..b86ed03f6a705 100644
> > > --- a/drivers/gpu/drm/i915/i915_perf.c
> > > +++ b/drivers/gpu/drm/i915/i915_perf.c
> > > @@ -3414,10 +3414,10 @@ i915_perf_open_ioctl_locked(struct i915_perf *perf,
> > >               struct drm_i915_file_private *file_priv = file->driver_priv;
> > >
> > >               specific_ctx = i915_gem_context_lookup(file_priv, ctx_handle);
> > > -             if (!specific_ctx) {
> > > +             if (IS_ERR(specific_ctx)) {
> > >                       DRM_DEBUG("Failed to look up context with ID %u for opening perf stream\n",
> > >                                 ctx_handle);
> > > -                     ret = -ENOENT;
> > > +                     ret = PTR_ERR(specific_ctx);
> >
> > Yeah this looks like a nice place to integrate this.
> >
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> >
> > One thing we need to make sure in the next patch or thereabouts is that
> > lookup can only return ENOENT or ENOMEM, but never EINVAL. I'll drop some
> > bikesheds on that :-)
> 
> I believe that is the case.  All -EINVAL should be handled in the
> proto-context code.
> 
> --Jason
> 
> > -Daniel
> >
> > >                       goto err;
> > >               }
> > >       }
> > > --
> > > 2.31.1
> > >
> > > _______________________________________________
> > > Intel-gfx mailing list
> > > Intel-gfx@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch

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