From bbb8a9d7e000c906f490780fab1c64faa1d08604 Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Fri, 12 Oct 2018 07:31:42 +0100 Subject: [PATCH] drm/i915: GEM_WARN_ON considered harmful GEM_WARN_ON currently has dangerous semantics where it is completely compiled out on !GEM_DEBUG builds. This can leave users who expect it to be more like a WARN_ON, just without a warning in non-debug builds, in complete ignorance. Another gotcha with it is that it cannot be used as a statement. Which is again different from a standard kernel WARN_ON. This patch fixes both problems by making it behave as one would expect. It can now be used both as an expression and as statement, and also the condition evaluates properly in all builds - code under the conditional will therefore not unexpectedly disappear. To satisfy call sites which really want the code under the conditional to completely disappear, we add GEM_DEBUG_WARN_ON and convert some of the callers to it. This one can also be used as both expression and statement. >From the above it follows GEM_DEBUG_WARN_ON should be used in situations where we are certain the condition will be hit during development, but at a place in code where error can be handled to the benefit of not crashing the machine. GEM_WARN_ON on the other hand should be used where condition may happen in production and we just want to distinguish the level of debugging output emitted between the production and debug build. v2: * Dropped BUG_ON hunk. Signed-off-by: Tvrtko Ursulin Cc: Chris Wilson Cc: Joonas Lahtinen Cc: Matthew Auld Cc: Mika Kuoppala Cc: Tomasz Lis Reviewed-by: Tomasz Lis Link: https://patchwork.freedesktop.org/patch/msgid/20181012063142.16080-1-tvrtko.ursulin@linux.intel.com --- drivers/gpu/drm/i915/i915_gem.h | 4 +++- drivers/gpu/drm/i915/i915_vma.c | 8 ++++---- drivers/gpu/drm/i915/intel_engine_cs.c | 8 ++++---- drivers/gpu/drm/i915/intel_lrc.c | 6 +++--- drivers/gpu/drm/i915/intel_workarounds.c | 2 +- 5 files changed, 15 insertions(+), 13 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h index 599c4f6eb1ea..b0e4b976880c 100644 --- a/drivers/gpu/drm/i915/i915_gem.h +++ b/drivers/gpu/drm/i915/i915_gem.h @@ -47,17 +47,19 @@ struct drm_i915_private; #define GEM_DEBUG_DECL(var) var #define GEM_DEBUG_EXEC(expr) expr #define GEM_DEBUG_BUG_ON(expr) GEM_BUG_ON(expr) +#define GEM_DEBUG_WARN_ON(expr) GEM_WARN_ON(expr) #else #define GEM_SHOW_DEBUG() (0) #define GEM_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr) -#define GEM_WARN_ON(expr) (BUILD_BUG_ON_INVALID(expr), 0) +#define GEM_WARN_ON(expr) ({ unlikely(!!(expr)); }) #define GEM_DEBUG_DECL(var) #define GEM_DEBUG_EXEC(expr) do { } while (0) #define GEM_DEBUG_BUG_ON(expr) +#define GEM_DEBUG_WARN_ON(expr) ({ BUILD_BUG_ON_INVALID(expr); 0; }) #endif #if IS_ENABLED(CONFIG_DRM_I915_TRACE_GEM) diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index 31efc971a3a8..82652c3d1bed 100644 --- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -305,12 +305,12 @@ int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level, GEM_BUG_ON(!drm_mm_node_allocated(&vma->node)); GEM_BUG_ON(vma->size > vma->node.size); - if (GEM_WARN_ON(range_overflows(vma->node.start, - vma->node.size, - vma->vm->total))) + if (GEM_DEBUG_WARN_ON(range_overflows(vma->node.start, + vma->node.size, + vma->vm->total))) return -ENODEV; - if (GEM_WARN_ON(!flags)) + if (GEM_DEBUG_WARN_ON(!flags)) return -EINVAL; bind_flags = 0; diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c index bc793b0c8806..8bfab22068a3 100644 --- a/drivers/gpu/drm/i915/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/intel_engine_cs.c @@ -273,13 +273,13 @@ intel_engine_setup(struct drm_i915_private *dev_priv, BUILD_BUG_ON(MAX_ENGINE_CLASS >= BIT(GEN11_ENGINE_CLASS_WIDTH)); BUILD_BUG_ON(MAX_ENGINE_INSTANCE >= BIT(GEN11_ENGINE_INSTANCE_WIDTH)); - if (GEM_WARN_ON(info->class > MAX_ENGINE_CLASS)) + if (GEM_DEBUG_WARN_ON(info->class > MAX_ENGINE_CLASS)) return -EINVAL; - if (GEM_WARN_ON(info->instance > MAX_ENGINE_INSTANCE)) + if (GEM_DEBUG_WARN_ON(info->instance > MAX_ENGINE_INSTANCE)) return -EINVAL; - if (GEM_WARN_ON(dev_priv->engine_class[info->class][info->instance])) + if (GEM_DEBUG_WARN_ON(dev_priv->engine_class[info->class][info->instance])) return -EINVAL; GEM_BUG_ON(dev_priv->engine[id]); @@ -402,7 +402,7 @@ int intel_engines_init(struct drm_i915_private *dev_priv) err = -EINVAL; err_id = id; - if (GEM_WARN_ON(!init)) + if (GEM_DEBUG_WARN_ON(!init)) goto cleanup; err = init(engine); diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index ff0e2b36cb8b..22b57b8926fc 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1515,7 +1515,7 @@ static int intel_init_workaround_bb(struct intel_engine_cs *engine) unsigned int i; int ret; - if (GEM_WARN_ON(engine->id != RCS)) + if (GEM_DEBUG_WARN_ON(engine->id != RCS)) return -EINVAL; switch (INTEL_GEN(engine->i915)) { @@ -1554,8 +1554,8 @@ static int intel_init_workaround_bb(struct intel_engine_cs *engine) */ for (i = 0; i < ARRAY_SIZE(wa_bb_fn); i++) { wa_bb[i]->offset = batch_ptr - batch; - if (GEM_WARN_ON(!IS_ALIGNED(wa_bb[i]->offset, - CACHELINE_BYTES))) { + if (GEM_DEBUG_WARN_ON(!IS_ALIGNED(wa_bb[i]->offset, + CACHELINE_BYTES))) { ret = -EINVAL; break; } diff --git a/drivers/gpu/drm/i915/intel_workarounds.c b/drivers/gpu/drm/i915/intel_workarounds.c index e4136590fed9..01b9b7591c5d 100644 --- a/drivers/gpu/drm/i915/intel_workarounds.c +++ b/drivers/gpu/drm/i915/intel_workarounds.c @@ -948,7 +948,7 @@ struct whitelist { static void whitelist_reg(struct whitelist *w, i915_reg_t reg) { - if (GEM_WARN_ON(w->count >= RING_MAX_NONPRIV_SLOTS)) + if (GEM_DEBUG_WARN_ON(w->count >= RING_MAX_NONPRIV_SLOTS)) return; w->reg[w->count++] = reg; -- 2.30.2