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Date:   Fri, 28 Jan 2022 09:46:47 +0100
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     Oliver Hartkopp <socketcan@hartkopp.net>
Cc:     "Ziyang Xuan (William)" <william.xuanziyang@huawei.com>,
        davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] can: isotp: isotp_rcv_cf(): fix so->rx race problem
Message-ID: <20220128084603.jvrvapqf5dt57yiq@pengutronix.de>
/From:  Marc Kleine-Budde <mkl@pengutronix.de>
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On 28.01.2022 09:32:40, Oliver Hartkopp wrote:
>=20
>=20
> On 28.01.22 09:07, Marc Kleine-Budde wrote:
> > On 28.01.2022 08:56:19, Oliver Hartkopp wrote:
> > > I've seen the frame processing sometimes freezes for one second when
> > > stressing the isotp_rcv() from multiple sources. This finally freezes
> > > the entire softirq which is either not good and not needed as we only
> > > need to fix this race for stress tests - and not for real world usage
> > > that does not create this case.
> >=20
> > Hmmm, this doesn't sound good. Can you test with LOCKDEP enabled?

> In kernel config? I enabled almost everything with LOCKing ;-)
>=20
>=20
> CONFIG_LOCKDEP_SUPPORT=3Dy
>=20
> CONFIG_HAVE_HARDLOCKUP_DETECTOR_PERF=3Dy
>=20
> CONFIG_ASN1=3Dy
> CONFIG_UNINLINE_SPIN_UNLOCK=3Dy
> CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=3Dy
> CONFIG_MUTEX_SPIN_ON_OWNER=3Dy
> CONFIG_RWSEM_SPIN_ON_OWNER=3Dy
> CONFIG_LOCK_SPIN_ON_OWNER=3Dy
> CONFIG_ARCH_USE_QUEUED_SPINLOCKS=3Dy
> CONFIG_QUEUED_SPINLOCKS=3Dy
> CONFIG_ARCH_USE_QUEUED_RWLOCKS=3Dy
> CONFIG_QUEUED_RWLOCKS=3Dy
> CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE=3Dy
> CONFIG_ARCH_HAS_SYNC_CORE_BEFORE_USERMODE=3Dy
> CONFIG_ARCH_HAS_SYSCALL_WRAPPER=3Dy
> CONFIG_FREEZER=3Dy
>=20
> CONFIG_HWSPINLOCK=3Dy
>=20
> CONFIG_I8253_LOCK=3Dy
>=20
> #
> # Debug Oops, Lockups and Hangs
> #
> # CONFIG_PANIC_ON_OOPS is not set
> CONFIG_PANIC_ON_OOPS_VALUE=3D0
> CONFIG_PANIC_TIMEOUT=3D0
> CONFIG_LOCKUP_DETECTOR=3Dy
> CONFIG_SOFTLOCKUP_DETECTOR=3Dy
> # CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC is not set
> CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE=3D0
> CONFIG_HARDLOCKUP_DETECTOR_PERF=3Dy
> CONFIG_HARDLOCKUP_CHECK_TIMESTAMP=3Dy
> CONFIG_HARDLOCKUP_DETECTOR=3Dy
> # CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is not set
> CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE=3D0
> CONFIG_DETECT_HUNG_TASK=3Dy
> CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=3D120 <--- the isotp timeout is 1000 ms =
what
> I can observe here with v1 patch
>=20
> # CONFIG_BOOTPARAM_HUNG_TASK_PANIC is not set
> CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE=3D0
> # CONFIG_WQ_WATCHDOG is not set
> # CONFIG_TEST_LOCKUP is not set
> # end of Debug Oops, Lockups and Hangs
>=20
> Only this debugging stuff is not really enabled:
>=20
> #
> # Lock Debugging (spinlocks, mutexes, etc...)
> #
> CONFIG_LOCK_DEBUGGING_SUPPORT=3Dy
> # CONFIG_PROVE_LOCKING is not set
CONFIG_PROVE_LOCKING=3Dy

Marc

> # CONFIG_LOCK_STAT is not set
> # CONFIG_DEBUG_RT_MUTEXES is not set
> # CONFIG_DEBUG_SPINLOCK is not set
> # CONFIG_DEBUG_MUTEXES is not set
> # CONFIG_DEBUG_WW_MUTEX_SLOWPATH is not set
> # CONFIG_DEBUG_RWSEMS is not set
> # CONFIG_DEBUG_LOCK_ALLOC is not set
> # CONFIG_DEBUG_ATOMIC_SLEEP is not set
> # CONFIG_DEBUG_LOCKING_API_SELFTESTS is not set
> # CONFIG_LOCK_TORTURE_TEST is not set
> # CONFIG_WW_MUTEX_SELFTEST is not set
> # CONFIG_SCF_TORTURE_TEST is not set
> # CONFIG_CSD_LOCK_WAIT_DEBUG is not set
> # end of Lock Debugging (spinlocks, mutexes, etc...)
>=20
> Would this help to be enabled for this test (of the v1 patch?
>=20
> Best regards,
> Oliver
>=20
>=20

--=20
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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