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drm/i915/gt: execlists->active is serialised by the tasklet

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The active/pending execlists is no longer protected by the
engine->active.lock, but is serialised by the tasklet instead. Update
the locking around the debug and stats to follow suit.

v2: local_bh_disable() to prevent recursing into the tasklet in case we
trigger a softirq (Tvrtko)

Fixes: df40306902 ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191009160906.16195-1-chris@chris-wilson.co.uk
(cherry picked from commit c36eebd9ba)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Chris Wilson 2019-10-09 17:09:06 +01:00 committed by Rodrigo Vivi
parent 749085a213
commit e137d3abdf
3 changed files with 27 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/gpu/drm/i915/gt/intel_engine.h
View File

@ -136,6 +136,20 @@ execlists_active(const struct intel_engine_execlists *execlists)
return READ_ONCE(*execlists->active);
}
static inline void
execlists_active_lock_bh(struct intel_engine_execlists *execlists)
{
local_bh_disable(); /* prevent local softirq and lock recursion */
tasklet_lock(&execlists->tasklet);
}
static inline void
execlists_active_unlock_bh(struct intel_engine_execlists *execlists)
{
tasklet_unlock(&execlists->tasklet);
local_bh_enable(); /* restore softirq, and kick ksoftirqd! */
}
struct i915_request *
execlists_unwind_incomplete_requests(struct intel_engine_execlists *execlists);

16
drivers/gpu/drm/i915/gt/intel_engine_cs.c
View File

@ -1197,9 +1197,7 @@ static void intel_engine_print_registers(struct intel_engine_cs *engine,
struct drm_printer *m)
{
struct drm_i915_private *dev_priv = engine->i915;
const struct intel_engine_execlists * const execlists =
&engine->execlists;
unsigned long flags;
struct intel_engine_execlists * const execlists = &engine->execlists;
u64 addr;
if (engine->id == RENDER_CLASS && IS_GEN_RANGE(dev_priv, 4, 7))
@ -1281,7 +1279,7 @@ static void intel_engine_print_registers(struct intel_engine_cs *engine,
idx, hws[idx * 2], hws[idx * 2 + 1]);
}
spin_lock_irqsave(&engine->active.lock, flags);
execlists_active_lock_bh(execlists);
for (port = execlists->active; (rq = *port); port++) {
char hdr[80];
int len;
@ -1309,7 +1307,7 @@ static void intel_engine_print_registers(struct intel_engine_cs *engine,
hwsp_seqno(rq));
print_request(m, rq, hdr);
}
spin_unlock_irqrestore(&engine->active.lock, flags);
execlists_active_unlock_bh(execlists);
} else if (INTEL_GEN(dev_priv) > 6) {
drm_printf(m, "\tPP_DIR_BASE: 0x%08x\n",
ENGINE_READ(engine, RING_PP_DIR_BASE));
@ -1440,8 +1438,8 @@ int intel_enable_engine_stats(struct intel_engine_cs *engine)
if (!intel_engine_supports_stats(engine))
return -ENODEV;
spin_lock_irqsave(&engine->active.lock, flags);
write_seqlock(&engine->stats.lock);
execlists_active_lock_bh(execlists);
write_seqlock_irqsave(&engine->stats.lock, flags);
if (unlikely(engine->stats.enabled == ~0)) {
err = -EBUSY;
@ -1469,8 +1467,8 @@ int intel_enable_engine_stats(struct intel_engine_cs *engine)
}
unlock:
write_sequnlock(&engine->stats.lock);
spin_unlock_irqrestore(&engine->active.lock, flags);
write_sequnlock_irqrestore(&engine->stats.lock, flags);
execlists_active_unlock_bh(execlists);
return err;
}

6
drivers/gpu/drm/i915/i915_gem.h
View File

@ -77,6 +77,12 @@ struct drm_i915_private;
#define I915_GEM_IDLE_TIMEOUT (HZ / 5)
static inline void tasklet_lock(struct tasklet_struct *t)
{
while (!tasklet_trylock(t))
cpu_relax();
}
static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
{
if (!atomic_fetch_inc(&t->count))