From: Jia-Ju Bai <baijiaju1990@gmail.com>
To: heikki.krogerus@linux.intel.com,
Greg KH <gregkh@linuxfoundation.org>,
kyletso@google.com, jackp@codeaurora.org,
andy.shevchenko@gmail.com, unixbhaskar@gmail.com,
subbaram@codeaurora.org, mrana@codeaurora.org
Cc: "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
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 [thread overview]
Message-ID: <037de7ac-e210-bdf5-ec7a-8c0c88a0be20@gmail.com> (raw)
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
next reply other threads:[~2022-02-09 4:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 3:50 Jia-Ju Bai [this message]
2022-02-09 14:30 ` [BUG] usb: typec: ucsi: possible deadlock in ucsi_pr_swap() and ucsi_handle_connector_change() Heikki Krogerus
2022-02-10 2:24 ` Jia-Ju Bai
2022-02-10 14:30 ` Heikki Krogerus
2022-03-25 20:39 ` Jack Pham
2022-03-28 8:28 ` Heikki Krogerus
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