From: Marcel Holtmann <marcel@holtmann.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: kbuild test robot <lkp@intel.com>,
"open list:BLUETOOTH DRIVERS" <linux-bluetooth@vger.kernel.org>,
kbuild-all@lists.01.org, Johan Hedberg <johan.hedberg@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Luis Claudio R . Goncalves" <lclaudio@uudg.org>
Subject: Re: [PATCH v2] Bluetooth: Acquire sk_lock.slock without disabling interrupts
Date: Fri, 29 May 2020 13:50:03 +0200 [thread overview]
Message-ID: <C6CE8EBA-73DC-4A8A-9BD2-BC13BBDEC24A@holtmann.org> (raw)
In-Reply-To: <20200528123512.o32lkytxjdpwzi7r@linutronix.de>
Hi Sebastian,
> There was a lockdep which led to commit
> fad003b6c8e3d ("Bluetooth: Fix inconsistent lock state with RFCOMM")
>
> Lockdep noticed that `sk->sk_lock.slock' was acquired without disabling
> the softirq while the lock was also used in softirq context.
> Unfortunately the solution back then was to disable interrupts before
> acquiring the lock which however made lockdep happy.
> It would have been enough to simply disable the softirq. Disabling
> interrupts before acquiring a spinlock_t is not allowed on PREEMPT_RT
> because these locks are converted to 'sleeping' spinlocks.
>
> Use spin_lock_bh() in order to acquire the `sk_lock.slock'.
>
> Reported-by: Luis Claudio R. Goncalves <lclaudio@uudg.org>
> Reported-by: kbuild test robot <lkp@intel.com> [missing unlock]
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>
> v1…v2: Unlock on the way out as reported by the lkp bot.
>
> net/bluetooth/rfcomm/sock.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
patch has been applied to bluetooth-next tree.
Regards
Marcel
prev parent reply other threads:[~2020-05-29 11:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 19:39 [PATCH] Bluetooth: Acquire sk_lock.slock without disabling interrupts Sebastian Andrzej Siewior
2020-05-28 7:11 ` kbuild test robot
2020-05-28 12:35 ` [PATCH v2] " Sebastian Andrzej Siewior
2020-05-29 11:50 ` Marcel Holtmann [this message]
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