Search Linux Wireless

Re: [PATCH v3 1/1] wifi: mac80211: fortify the spinlock against deadlock by interrupt

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 25.4.2023. 17:33, Leon Romanovsky wrote:
On Tue, Apr 25, 2023 at 11:35:48AM +0200, Mirsad Goran Todorovac wrote:
In the function ieee80211_tx_dequeue() there is a particular locking
sequence:

begin:
	spin_lock(&local->queue_stop_reason_lock);
	q_stopped = local->queue_stop_reasons[q];
	spin_unlock(&local->queue_stop_reason_lock);

However small the chance (increased by ftracetest), an asynchronous
interrupt can occur in between of spin_lock() and spin_unlock(),
and the interrupt routine will attempt to lock the same
&local->queue_stop_reason_lock again.

This will cause a costly reset of the CPU and the wifi device or an
altogether hang in the single CPU and single core scenario.

This is the probable trace of the deadlock:

Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel:  Possible unsafe locking scenario:
Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel:        CPU0
Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel:        ----
Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel:   lock(&local->queue_stop_reason_lock);
Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel:   <Interrupt>
Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel:     lock(&local->queue_stop_reason_lock);
Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel:
                                                  *** DEADLOCK ***

Can you please add to the commit message whole lockdep trace?

And please trim "Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: " line prefix,
it doesn't add any value.

Sure. I will do this ASAP. I thought of it myself, but I reckoned it would
be an overkill.

Will come in PATCH v4.

Best regards,
Mirsad

--
Mirsad Todorovac
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb
Republic of Croatia, the European Union

Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu




[Index of Archives]     [Linux Host AP]     [ATH6KL]     [Linux Wireless Personal Area Network]     [Linux Bluetooth]     [Wireless Regulations]     [Linux Netdev]     [Kernel Newbies]     [Linux Kernel]     [IDE]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Hiking]     [MIPS Linux]     [ARM Linux]     [Linux RAID]

  Powered by Linux