drm/i915: Make intel_engine_dump irqsafe

To be useful later, enable intel_engine_dump() to be called from irq
context (i.e. using saving and restoring irq start rather than assuming
we enter with irqs enabled).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180518090212.5349-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index a2173e6..8477972 100644 (file)
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1367,6 +1367,7 @@ void intel_engine_dump(struct intel_engine_cs *engine,
        const struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_gpu_error * const error = &engine->i915->gpu_error;
        struct i915_request *rq, *last;
+       unsigned long flags;
        struct rb_node *rb;
        int count;
 
@@ -1433,7 +1434,8 @@ void intel_engine_dump(struct intel_engine_cs *engine,
                drm_printf(m, "\tDevice is asleep; skipping register dump\n");
        }
 
-       spin_lock_irq(&engine->timeline.lock);
+       local_irq_save(flags);
+       spin_lock(&engine->timeline.lock);
 
        last = NULL;
        count = 0;
@@ -1475,16 +1477,17 @@ void intel_engine_dump(struct intel_engine_cs *engine,
                print_request(m, last, "\t\tQ ");
        }
 
-       spin_unlock_irq(&engine->timeline.lock);
+       spin_unlock(&engine->timeline.lock);
 
-       spin_lock_irq(&b->rb_lock);
+       spin_lock(&b->rb_lock);
        for (rb = rb_first(&b->waiters); rb; rb = rb_next(rb)) {
                struct intel_wait *w = rb_entry(rb, typeof(*w), node);
 
                drm_printf(m, "\t%s [%d] waiting for %x\n",
                           w->tsk->comm, w->tsk->pid, w->seqno);
        }
-       spin_unlock_irq(&b->rb_lock);
+       spin_unlock(&b->rb_lock);
+       local_irq_restore(flags);
 
        drm_printf(m, "IRQ? 0x%lx (breadcrumbs? %s) (execlists? %s)\n",
                   engine->irq_posted,