From: Dhinakaran Pandiyan Date: Mon, 25 Jun 2018 05:47:40 +0000 (-0700) Subject: drm/i915/psr: Fix race in intel_psr_work() X-Git-Tag: v4.19-rc1~138^2~22^2~100 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=c12e0643a05d978657877630d4da1ace06ea3720;p=linux.git drm/i915/psr: Fix race in intel_psr_work() 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 Cc: Chris Wilson Cc: José Roberto de Souza Signed-off-by: Dhinakaran Pandiyan Reviewed-by: Chris Wilson Reviewed-by: Rodrigo Vivi Link: https://patchwork.freedesktop.org/patch/msgid/20180625054741.3919-1-dhinakaran.pandiyan@intel.com --- diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c index ccaee4a748f2..276070d597e1 100644 --- 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_struct *work) * 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);