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drm/i915/execlists: Assert tasklet is locked for process_csb() 

We rely on only the tasklet being allowed to call into process_csb(), so
assert that is locked when we do. As the tasklet uses a simple bitlock,
there is no strong lockdep checking so we must make do with a plain
assertion that the tasklet is running and assume that we are the
tasklet!

v2: Fixup intel_gt_sanitize() to prepare each engine for the reset so
that the locks are marked as held during the reset
v3: Check for existent function pointers for very early sanitisation.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191014121336.30137-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2019-10-14 13:13:36 +01:00
parent 53448aed7b
commit 3c00660db1
3 changed files with 22 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/gpu/drm/i915/gt/intel_gt_pm.c
View File

@ -136,11 +136,18 @@ void intel_gt_sanitize(struct intel_gt *gt, bool force)
intel_uc_sanitize(&gt->uc);
if (!reset_engines(gt) && !force)
return;
for_each_engine(engine, gt->i915, id)
if (engine->reset.prepare)
engine->reset.prepare(engine);
if (reset_engines(gt) || force) {
for_each_engine(engine, gt->i915, id)
__intel_engine_reset(engine, false);
}
for_each_engine(engine, gt->i915, id)
__intel_engine_reset(engine, false);
if (engine->reset.finish)
engine->reset.finish(engine);
}
void intel_gt_pm_disable(struct intel_gt *gt)

7
drivers/gpu/drm/i915/gt/intel_lrc.c
View File

@ -1842,6 +1842,13 @@ static void process_csb(struct intel_engine_cs *engine)
const u8 num_entries = execlists->csb_size;
u8 head, tail;
/*
* As we modify our execlists state tracking we require exclusive
* access. Either we are inside the tasklet, or the tasklet is disabled
* and we assume that is only inside the reset paths and so serialised.
*/
GEM_BUG_ON(!tasklet_is_locked(&execlists->tasklet) &&
!reset_in_progress(execlists));
GEM_BUG_ON(USES_GUC_SUBMISSION(engine->i915));
/*

5
drivers/gpu/drm/i915/i915_gem.h
View File

@ -86,6 +86,11 @@ static inline void tasklet_lock(struct tasklet_struct *t)
cpu_relax();
}
static inline bool tasklet_is_locked(const struct tasklet_struct *t)
{
return test_bit(TASKLET_STATE_RUN, &t->state);
}
static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
{
if (!atomic_fetch_inc(&t->count))