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Date:      Thu, 18 Aug 2016 11:25:26 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-bugs@FreeBSD.org
Subject:   [Bug 211962] bxe driver queue soft hangs and flooding tx_soft_errors
Message-ID:  <bug-211962-8@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D211962

            Bug ID: 211962
           Summary: bxe driver queue soft hangs and flooding
                    tx_soft_errors
           Product: Base System
           Version: 10.3-RELEASE
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: freebsd-bugs@FreeBSD.org
          Reporter: aler@playground.ru

Hardware (from dmesg): QLogic NetXtreme II BCM57711E 10GbE (A0) BXE v:1.78.=
79
(but this seems not important here)

Sometimes (randomly) bxe driver reduces its sending speed to very slow valu=
es,
and one or more queues fastly increases dev.bxe.#.queue.#.tx_soft_errors va=
lue.
This can be stopped and returned to normal operation only by restarting the
interface (ifconfig down + ifconfig up).

It seems i found the bug that causes this.
In bxe_tx_mq_start_locked(), when we have both pending and new packet, it f=
irst
tries to enqueue new packet and exits on fail. After that, it dequeues pend=
ing
packet and tryes to handle it.
Sometimes the tx queue gets overflowed by accident. It is nothing bad, bad =
what
happens next: bxe_tx_mq_start_locked() getting called again and again, with=
 new
packets that TCP layer trying to send. Everytime called it tryes to enqueue
them, fails and exits, having no way to handle pending packets and reduce q=
ueue
length.

I'm new to bxe driver source code and can be wrong but the patch seems fixed
the problem.

--=20
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