From: Chris Wilson Date: Fri, 9 Sep 2016 13:11:52 +0000 (+0100) Subject: drm/i915: Replace wait-on-mutex with wait-on-bit in reset worker X-Git-Tag: v4.14-rc1~674^2~37^2~1331 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=780f262a703a683bc56bbb860b25286a6f501d61;p=platform%2Fkernel%2Flinux-rpi.git drm/i915: Replace wait-on-mutex with wait-on-bit in reset worker Since we have a cooperative mode now with a direct reset, we can avoid the contention on struct_mutex and instead try then sleep on the I915_RESET_IN_PROGRESS bit. If the mutex is held and that bit is cleared, all is fine. Otherwise, we sleep for a bit and try again. In the worst case we sleep for an extra second waiting for the mutex to be released (no one touching the GPU is allowed the struct_mutex whilst the I915_RESET_IN_PROGRESS bit is set). But when we have a direct reset, this allows us to clean up the reset worker faster. v2: Remember to call wake_up_bit() after changing (for the faster wakeup as promised) Signed-off-by: Chris Wilson Reviewed-by: Mika Kuoppala Link: http://patchwork.freedesktop.org/patch/msgid/20160909131201.16673-12-chris@chris-wilson.co.uk --- diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index ff4173e..f2614b2 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -1726,8 +1726,8 @@ int i915_resume_switcheroo(struct drm_device *dev) * i915_reset - reset chip after a hang * @dev: drm device to reset * - * Reset the chip. Useful if a hang is detected. Returns zero on successful - * reset or otherwise an error code. + * Reset the chip. Useful if a hang is detected. Marks the device as wedged + * on failure. * * Caller must hold the struct_mutex. * @@ -1739,7 +1739,7 @@ int i915_resume_switcheroo(struct drm_device *dev) * - re-init interrupt state * - re-init display */ -int i915_reset(struct drm_i915_private *dev_priv) +void i915_reset(struct drm_i915_private *dev_priv) { struct drm_device *dev = &dev_priv->drm; struct i915_gpu_error *error = &dev_priv->gpu_error; @@ -1748,7 +1748,7 @@ int i915_reset(struct drm_i915_private *dev_priv) lockdep_assert_held(&dev->struct_mutex); if (!test_and_clear_bit(I915_RESET_IN_PROGRESS, &error->flags)) - return test_bit(I915_WEDGED, &error->flags) ? -EIO : 0; + return; /* Clear any previous failed attempts at recovery. Time to try again. */ __clear_bit(I915_WEDGED, &error->flags); @@ -1798,11 +1798,13 @@ int i915_reset(struct drm_i915_private *dev_priv) intel_sanitize_gt_powersave(dev_priv); intel_autoenable_gt_powersave(dev_priv); - return 0; +wakeup: + wake_up_bit(&error->flags, I915_RESET_IN_PROGRESS); + return; error: set_bit(I915_WEDGED, &error->flags); - return ret; + goto wakeup; } static int i915_pm_suspend(struct device *kdev) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 15f1977..9a9f07f 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2884,7 +2884,7 @@ extern long i915_compat_ioctl(struct file *filp, unsigned int cmd, #endif extern int intel_gpu_reset(struct drm_i915_private *dev_priv, u32 engine_mask); extern bool intel_has_gpu_reset(struct drm_i915_private *dev_priv); -extern int i915_reset(struct drm_i915_private *dev_priv); +extern void i915_reset(struct drm_i915_private *dev_priv); extern int intel_guc_reset(struct drm_i915_private *dev_priv); extern void intel_engine_init_hangcheck(struct intel_engine_cs *engine); extern unsigned long i915_chipset_val(struct drm_i915_private *dev_priv); diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 2c7cb50..ef2d402 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -2497,7 +2497,6 @@ static void i915_reset_and_wakeup(struct drm_i915_private *dev_priv) char *error_event[] = { I915_ERROR_UEVENT "=1", NULL }; char *reset_event[] = { I915_RESET_UEVENT "=1", NULL }; char *reset_done_event[] = { I915_ERROR_UEVENT "=0", NULL }; - int ret; kobject_uevent_env(kobj, KOBJ_CHANGE, error_event); @@ -2512,24 +2511,30 @@ static void i915_reset_and_wakeup(struct drm_i915_private *dev_priv) * simulated reset via debugs, so get an RPM reference. */ intel_runtime_pm_get(dev_priv); - intel_prepare_reset(dev_priv); - /* - * All state reset _must_ be completed before we update the - * reset counter, for otherwise waiters might miss the reset - * pending state and not properly drop locks, resulting in - * deadlocks with the reset work. - */ - mutex_lock(&dev_priv->drm.struct_mutex); - ret = i915_reset(dev_priv); - mutex_unlock(&dev_priv->drm.struct_mutex); + do { + /* + * All state reset _must_ be completed before we update the + * reset counter, for otherwise waiters might miss the reset + * pending state and not properly drop locks, resulting in + * deadlocks with the reset work. + */ + if (mutex_trylock(&dev_priv->drm.struct_mutex)) { + i915_reset(dev_priv); + mutex_unlock(&dev_priv->drm.struct_mutex); + } - intel_finish_reset(dev_priv); + /* We need to wait for anyone holding the lock to wakeup */ + } while (wait_on_bit_timeout(&dev_priv->gpu_error.flags, + I915_RESET_IN_PROGRESS, + TASK_UNINTERRUPTIBLE, + HZ)); + intel_finish_reset(dev_priv); intel_runtime_pm_put(dev_priv); - if (ret == 0) + if (!test_bit(I915_WEDGED, &dev_priv->gpu_error.flags)) kobject_uevent_env(kobj, KOBJ_CHANGE, reset_done_event);