On 17/05/18 18:23, Mark Brown wrote:
On Thu, May 17, 2018 at 06:10:49PM +0100, Srinivas Kandagatla wrote:
On 17/05/18 07:55, Mark Brown wrote:
On Wed, May 09, 2018 at 01:56:20PM +0100, Srinivas Kandagatla wrote:

This lock only protects the list, it does nothing to ensure that the
port we look up is still valid by the time we return to the caller.
That means we won't crash during list traversal but does nothing to
ensure we won't crash immediately afterwards if the port is deallocated
just after we look it up.  What stops that happening?

Each port is allocated and de-allocated in dai probe and remove calls
respectively.

Lets say... So for this case to happen the dai has to be removed (unload
module) at the same time when the interrupt callback happens due to delayed
response from previous commands.

This case would be almost impossible because all the calls to afe service
are synchronous with timeouts, if any of the previous calls times out the
respective caller would get an error, this should prevent him from unloading
the module in the first place.

The user can also trigger manual unbinds without unloading the module,
and to be honet the scenario where the DSP has stopped responding well
and is delaying responses sounds like exactly the sort of time when
users might try to reload the driver...Yes, that is one possible usecase!
ref-counting port should stop that from happening.
I will add this in next spin!

thanks,
srini




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