From c36eebd9ba5d70b84e1e7408ccc7632566f285c4 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 9 Oct 2019 17:09:06 +0100 Subject: [PATCH] drm/i915/gt: execlists->active is serialised by the tasklet 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: df403069029d ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock") Signed-off-by: Chris Wilson Cc: Mika Kuoppala Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20191009160906.16195-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gt/intel_engine.h | 14 ++++++++++++++ drivers/gpu/drm/i915/gt/intel_engine_cs.c | 16 +++++++--------- drivers/gpu/drm/i915/i915_gem.h | 6 ++++++ 3 files changed, 27 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h index d624752f2a92..93ea367fe624 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine.h +++ b/drivers/gpu/drm/i915/gt/intel_engine.h @@ -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); diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 5aa1371f6a0f..c9d639c6becb 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -1245,9 +1245,7 @@ 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)) @@ -1329,7 +1327,7 @@ 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; @@ -1367,7 +1365,7 @@ static void intel_engine_print_registers(struct intel_engine_cs *engine, if (tl) intel_timeline_put(tl); } - 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)); @@ -1509,8 +1507,8 @@ 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; @@ -1538,8 +1536,8 @@ 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; } diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h index 167a7b56ed5b..6795f1daa3d5 100644 --- a/drivers/gpu/drm/i915/i915_gem.h +++ b/drivers/gpu/drm/i915/i915_gem.h @@ -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)) -- 2.11.0