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

[Jason Ekstrand]

On Thu, Apr 29, 2021 at 8:27 AM Daniel Vetter <daniel at 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 at 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"


> > @@ -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 at 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 at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch