drm/i915: Only emit the 'send bug report' once for a GPU hang

Use a locked xchg to ensure that the global log message giving
instructions on how to send a bug report is emitted precisely once.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190819075835.20065-5-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 0c1995c..52f22e8 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1764,7 +1764,7 @@ void i915_capture_error_state(struct drm_i915_private *i915,
                return;
        }
 
-       if (!warned &&
+       if (!xchg(&warned, true) &&
            ktime_get_real_seconds() - DRIVER_TIMESTAMP < DAY_AS_SECONDS(180)) {
                pr_info("GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.\n");
                pr_info("Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel\n");
@@ -1772,7 +1772,6 @@ void i915_capture_error_state(struct drm_i915_private *i915,
                pr_info("The GPU crash dump is required to analyze GPU hangs, so please always attach it.\n");
                pr_info("GPU crash dump saved to /sys/class/drm/card%d/error\n",
                        i915->drm.primary->index);
-               warned = true;
        }
 }