linux_dsm_epyc7002/drivers/gpu/drm/i915/i915_gem.h
Tvrtko Ursulin bbb8a9d7e0 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 <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Tomasz Lis <tomasz.lis@intel.com>
Reviewed-by: Tomasz Lis <tomasz.lis@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181012063142.16080-1-tvrtko.ursulin@linux.intel.com
2018-10-18 10:10:12 +01:00

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C

/*
* Copyright © 2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
*/
#ifndef __I915_GEM_H__
#define __I915_GEM_H__
#include <linux/bug.h>
#include <linux/interrupt.h>
struct drm_i915_private;
#ifdef CONFIG_DRM_I915_DEBUG_GEM
#define GEM_SHOW_DEBUG() (drm_debug & DRM_UT_DRIVER)
#define GEM_BUG_ON(condition) do { if (unlikely((condition))) { \
pr_err("%s:%d GEM_BUG_ON(%s)\n", \
__func__, __LINE__, __stringify(condition)); \
GEM_TRACE("%s:%d GEM_BUG_ON(%s)\n", \
__func__, __LINE__, __stringify(condition)); \
BUG(); \
} \
} while(0)
#define GEM_WARN_ON(expr) WARN_ON(expr)
#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) ({ 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)
#define GEM_TRACE(...) trace_printk(__VA_ARGS__)
#define GEM_TRACE_DUMP() ftrace_dump(DUMP_ALL)
#define GEM_TRACE_DUMP_ON(expr) \
do { if (expr) ftrace_dump(DUMP_ALL); } while (0)
#else
#define GEM_TRACE(...) do { } while (0)
#define GEM_TRACE_DUMP() do { } while (0)
#define GEM_TRACE_DUMP_ON(expr) BUILD_BUG_ON_INVALID(expr)
#endif
#define I915_NUM_ENGINES 8
void i915_gem_park(struct drm_i915_private *i915);
void i915_gem_unpark(struct drm_i915_private *i915);
static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
{
if (atomic_inc_return(&t->count) == 1)
tasklet_unlock_wait(t);
}
static inline bool __tasklet_is_enabled(const struct tasklet_struct *t)
{
return !atomic_read(&t->count);
}
#endif /* __I915_GEM_H__ */