Re: [PATCH] rpmsg: glink: Remove channel decouple from rpdev release

From: Chris Lew
Date: Fri Oct 11 2019 - 14:43:29 EST

On 10/9/2019 10:04 PM, Stephen Boyd wrote:
Quoting Chris Lew (2019-10-08 18:33:45)
If a channel is being rapidly restarted and the kobj release worker is
busy, there is a chance the the rpdev_release function will run after
the channel struct itself has been released.

There should not be a need to decouple the channel from rpdev in the
rpdev release since that should only happen from the channel close

Signed-off-by: Chris Lew <clew@xxxxxxxxxxxxxx>

Fixes tag? The whole thing sounds broken and probably is still racy in
the face of SMP given that channel->rpdev is tested for "published" or
not. Can you describe the race that you're closing more?

Thanks Stephen, will add Fixes tag and try to describe the race better.

I agree that the whole thing sounds broken, the glink channel cleanup code has a couple bugs that need to be addressed in a more extensive patch. This patch is more to address the immediate issue of a use-after-free from one of the races.

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project