drm/i915/gt: Lift set-wedged engine dumping out of user paths

The user (e.g. gem_eio) can manipulate the driver into wedging itself,
allowing the user to trigger voluminous logging of inconsequential
details. If we lift the dump to direct calls to intel_gt_set_wedged(),
out of the intel_reset failure handling, we keep the detail logging for
what we expect are true HW or test failures without being tricked.

Reported-by: Tomi Sarvela <tomi.p.sarvela@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200127231540.3302516-6-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
index beee0cf..ea983ef 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -800,13 +800,6 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
        if (test_bit(I915_WEDGED, &gt->reset.flags))
                return;
 
-       if (GEM_SHOW_DEBUG() && !intel_engines_are_idle(gt)) {
-               struct drm_printer p = drm_debug_printer(__func__);
-
-               for_each_engine(engine, gt, id)
-                       intel_engine_dump(engine, &p, "%s\n", engine->name);
-       }
-
        GT_TRACE(gt, "start\n");
 
        /*
@@ -845,10 +838,30 @@ void intel_gt_set_wedged(struct intel_gt *gt)
 {
        intel_wakeref_t wakeref;
 
+       if (test_bit(I915_WEDGED, &gt->reset.flags))
+               return;
+
+       wakeref = intel_runtime_pm_get(gt->uncore->rpm);
        mutex_lock(&gt->reset.mutex);
-       with_intel_runtime_pm(gt->uncore->rpm, wakeref)
-               __intel_gt_set_wedged(gt);
+
+       if (GEM_SHOW_DEBUG()) {
+               struct drm_printer p = drm_debug_printer(__func__);
+               struct intel_engine_cs *engine;
+               enum intel_engine_id id;
+
+               drm_printf(&p, "called from %pS\n", (void *)_RET_IP_);
+               for_each_engine(engine, gt, id) {
+                       if (intel_engine_is_idle(engine))
+                               continue;
+
+                       intel_engine_dump(engine, &p, "%s\n", engine->name);
+               }
+       }
+
+       __intel_gt_set_wedged(gt);
+
        mutex_unlock(&gt->reset.mutex);
+       intel_runtime_pm_put(gt->uncore->rpm, wakeref);
 }
 
 static bool __intel_gt_unset_wedged(struct intel_gt *gt)