From: Dhinakaran Pandiyan <dhinakaran.pandiyan@gmail.com>
Date: Sun, 24 Jun 2018 22:47:40 -0700
Subject: drm/i915/psr: Fix race in intel_psr_work()
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Git-commit: c12e0643a05d978657877630d4da1ace06ea3720
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
Commit 5422b37c907e ("drm/i915/psr: Kill delays when activating psr
back.") switched from delayed work to the plain variant and while doing so
removed the check for work_busy() before scheduling a PSR activation.
This appears to cause consecutive executions of psr_activate() in this
scenario - after a worker picks up the PSR work item for execution and
before the work function can acquire the PSR mutex, a psr_flush() can
get hold of the mutex and schedule another PSR work. Without a psr_exit()
between the two psr_activate() calls, warning messages get printed.
Further, since we drop the mutex in the midst of psr_work() to wait for
PSR to idle, another work item can also get scheduled. Fix this by
returning if PSR was already active.
Fixes: 5422b37c907e ("drm/i915/psr: Kill delays when activating psr back.")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106948
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180625054741.3919-1-dhinakaran.pandiyan@intel.com
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/intel_psr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -758,7 +758,7 @@ static void intel_psr_work(struct work_s
* recheck. Since psr_flush first clears this and then reschedules we
* won't ever miss a flush when bailing out here.
*/
- if (dev_priv->psr.busy_frontbuffer_bits)
+ if (dev_priv->psr.busy_frontbuffer_bits || dev_priv->psr.active)
goto unlock;
intel_psr_activate(dev_priv->psr.enabled);