Messages in this thread | | | Date | Thu, 1 Sep 2022 05:42:00 +0900 | From | asmadeus@codewrec ... | Subject | Re: [PATCH] p9: trans_fd: Fix deadlock when connection cancel |
| |
Schspa Shi wrote on Thu, Sep 01, 2022 at 02:09:50AM +0800: > To fix it, we can add extra reference counter to avoid deadlock, and > decrease it after we unlock the client->lock.
Thanks for the patch!
Unfortunately I already sent a slightly different version to the list, hidden in another syzbot thread, here: https://lkml.kernel.org/r/YvyD053bdbGE9xoo@codewreck.org
(yes, sorry, not exactly somewhere I'd expect someone to find it... 9p hasn't had many contributors recently)
Basically instead of taking an extra lock I just released the client lock before calling p9_client_cb, so it shouldn't hang anymore.
We don't need the lock to call the cb as in p9_conn_cancel we already won't accept any new request and by this point the requests are in a local list that isn't shared anywhere.
If you have a test setup, would you mind testing my patch? That's the main reason I was delaying pushing it.
Since you went out of your way to make this patch if you agree with my approach I don't mind adding your sign off or another mark of having worked on it.
Thank you, -- Dominique
| |