Re: [PATCH v4 3/8] drm/xe/survivability: Guard runtime survivability enable against unbind

[Raag Jadav <raag.jadav@intel.com>]

On Wed, Nov 11, 2026 at 11:20:02AM +0530, Tauro, Riana wrote:
> On 11-11-2026 11:09, Raag Jadav wrote:
> > On Wed, Nov 11, 2026 at 10:13:44AM +0530, Tauro, Riana wrote:
> > > On 10-11-2026 18:21, Raag Jadav wrote:
> > > > On Fri, Nov 06, 2026 at 12:49:48PM +0530, Riana Tauro wrote:
> > > > > Runtime surivability mode creates sysfs and declares the device as
> > > > > wedged in a worker thread. This can race with unbind.
> > > > > 
> > > > > During unbind, devres actions such as disabling the worker run as part of
> > > > > teardown. A runtime survivability enable that is still in flight or gets
> > > > > scheduled in that window can create the survivability sysfs entries while
> > > > > the device is being removed. This is incorrect, as runtime survivability mode
> > > > > must not be entered once during devres teardown.
> > > > > 
> > > > > Use the DRM device enter/exit protection so that the enable path
> > > > > synchronizes with device unplug and returns early if the device is
> > > > > already being unbound.
> > > > I'm a bit lost here. Doesn't disable_work_sync() already guarantee this?
> > > If the worker is already queued and there is a unbind in progress. The
> > > disable work sync from devm
> > > action waits for the worker to complete. This causes the device to enter
> > > survivability mode during unbind
> > > which is not intended.
> > Wouldn't the survivability stuff still land on devres and get cleaned
> > up anyway?
> 
> devres_release_all running as part of unbind copies all the devres nodes
> into a todo list and then
> releases them. If during release, we add a new devres that will not be
> cleared during unbind
> which can cause stale sysfs.

Hm, I thought all the devm actions are protected by devres_lock but
you're right.

A more robust fix would be to disable all the workers in ->remove()
callback itself and avoid such races to begin with, but I'll leave it
upto you.

Raag