Re: [PATCH][next] drm/i915/gem: Fix fall-through warning for Clang

On Mon, 2021-06-07 at 15:32 -0500, Gustavo A. R. Silva wrote:

In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning by explicitly adding a fallthrough; statement.

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diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c

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@@ -62,6 +62,7 @@ static void try_to_writeback(struct drm_i915_gem_object *obj,   switch (obj->mm.madv) {   case I915_MADV_DONTNEED:   i915_gem_object_truncate(obj);

• fallthrough;
  

case __I915_MADV_PURGED:   return;   }

I think fallthrough to return is not particularly nice to follow.

This is the current function:

static void try_to_writeback(struct drm_i915_gem_object *obj, unsigned int flags) { switch (obj->mm.madv) { case I915_MADV_DONTNEED: i915_gem_object_truncate(obj); case __I915_MADV_PURGED: return; }

if (flags & I915_SHRINK_WRITEBACK) i915_gem_object_writeback(obj); }

One of these might be more typical:

static void try_to_writeback(struct drm_i915_gem_object *obj, unsigned int flags) { switch (obj->mm.madv) { case I915_MADV_DONTNEED: i915_gem_object_truncate(obj); break; case __I915_MADV_PURGED: break; default: if (flags & I915_SHRINK_WRITEBACK) i915_gem_object_writeback(obj); break; } }

or maybe:

static void try_to_writeback(struct drm_i915_gem_object *obj, unsigned int flags) { switch (obj->mm.madv) { case I915_MADV_DONTNEED: i915_gem_object_truncate(obj); return; case __I915_MADV_PURGED: return; }

if (flags & I915_SHRINK_WRITEBACK) i915_gem_object_writeback(obj); }