Messages in this thread | | | From | Jia-Ju Bai <> | Subject | [BUG] usb: typec: ucsi: possible deadlock in ucsi_pr_swap() and ucsi_handle_connector_change() | Date | Wed, 9 Feb 2022 11:50:57 +0800 |
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Hello,
My static analysis tool reports a possible deadlock in the ucsi driver in Linux 5.16:
ucsi_pr_swap() mutex_lock(&con->lock); --> Line 962 (Lock A) wait_for_completion_timeout(&con->complete, ...) --> Line 981 (Wait X)
ucsi_handle_connector_change() mutex_lock(&con->lock); --> Line 763 (Lock A) complete(&con->complete); --> Line 782 (Wake X) complete(&con->complete); --> Line 807 (Wake X)
When ucsi_pr_swap() is executed, "Wait X" is performed by holding "Lock A". If ucsi_handle_connector_change() is executed at this time, "Wake X" cannot be performed to wake up "Wait X" in ucsi_handle_connector_change(), because "Lock A" has been already held by ucsi_handle_connector_change(), causing a possible deadlock. I find that "Wait X" is performed with a timeout, to relieve the possible deadlock; but I think this timeout can cause inefficient execution.
I am not quite sure whether this possible problem is real. Any feedback would be appreciated, thanks :)
Best wishes, Jia-Ju Bai
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