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Message-ID: <72419ca8-b0cb-1e9d-3fcc-655defb662df@hartkopp.net>
Date:   Fri, 28 Jan 2022 09:32:40 +0100
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Subject: Re: [PATCH net] can: isotp: isotp_rcv_cf(): fix so->rx race problem
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To:     Marc Kleine-Budde <mkl@pengutronix.de>
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
References: <53279d6d-298c-5a85-4c16-887c95447825@hartkopp.net>
 <280e10c1-d1f4-f39e-fa90-debd56f1746d@huawei.com>
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 <1fb4407a-1269-ec50-0ad5-074e49f91144@hartkopp.net>
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 <64695483-ff75-4872-db81-ca55763f95cf@hartkopp.net>
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 <97339463-b357-3e0e-1cbf-c66415c08129@hartkopp.net>
 <24e6da96-a3e5-7b4e-102b-b5676770b80e@hartkopp.net>
 <20220128080704.ns5fzbyn72wfoqmx@pengutronix.de>
From:   Oliver Hartkopp <socketcan@hartkopp.net>
In-Reply-To: <20220128080704.ns5fzbyn72wfoqmx@pengutronix.de>
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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.
> 
> Hmmm, this doesn't sound good. Can you test with LOCKDEP enabled?

In kernel config? I enabled almost everything with LOCKing ;-)


CONFIG_LOCKDEP_SUPPORT=y

CONFIG_HAVE_HARDLOCKUP_DETECTOR_PERF=y

CONFIG_ASN1=y
CONFIG_UNINLINE_SPIN_UNLOCK=y
CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=y
CONFIG_MUTEX_SPIN_ON_OWNER=y
CONFIG_RWSEM_SPIN_ON_OWNER=y
CONFIG_LOCK_SPIN_ON_OWNER=y
CONFIG_ARCH_USE_QUEUED_SPINLOCKS=y
CONFIG_QUEUED_SPINLOCKS=y
CONFIG_ARCH_USE_QUEUED_RWLOCKS=y
CONFIG_QUEUED_RWLOCKS=y
CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE=y
CONFIG_ARCH_HAS_SYNC_CORE_BEFORE_USERMODE=y
CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y
CONFIG_FREEZER=y

CONFIG_HWSPINLOCK=y

CONFIG_I8253_LOCK=y

#
# Debug Oops, Lockups and Hangs
#
# CONFIG_PANIC_ON_OOPS is not set
CONFIG_PANIC_ON_OOPS_VALUE=0
CONFIG_PANIC_TIMEOUT=0
CONFIG_LOCKUP_DETECTOR=y
CONFIG_SOFTLOCKUP_DETECTOR=y
# CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC is not set
CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE=0
CONFIG_HARDLOCKUP_DETECTOR_PERF=y
CONFIG_HARDLOCKUP_CHECK_TIMESTAMP=y
CONFIG_HARDLOCKUP_DETECTOR=y
# CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is not set
CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE=0
CONFIG_DETECT_HUNG_TASK=y
CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=120 <--- the isotp timeout is 1000 ms 
what I can observe here with v1 patch

# CONFIG_BOOTPARAM_HUNG_TASK_PANIC is not set
CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE=0
# CONFIG_WQ_WATCHDOG is not set
# CONFIG_TEST_LOCKUP is not set
# end of Debug Oops, Lockups and Hangs

Only this debugging stuff is not really enabled:

#
# Lock Debugging (spinlocks, mutexes, etc...)
#
CONFIG_LOCK_DEBUGGING_SUPPORT=y
# CONFIG_PROVE_LOCKING is not set
# 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...)

Would this help to be enabled for this test (of the v1 patch?

Best regards,
Oliver