From: Thomas Gleixner <tglx@linutronix.de>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Johan Hovold <johan@kernel.org>,
Eric Dumazet <edumazet@google.com>,
netdev <netdev@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-serial@vger.kernel.org
Subject: Re: [patch 1/1] genirq: Disable interrupts for force threaded handlers
Date: Wed, 17 Mar 2021 17:09:55 +0100 [thread overview]
Message-ID: <87pmzxyd64.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210317144806.y4dogv6n2s62fpnw@linutronix.de>
On Wed, Mar 17 2021 at 15:48, Sebastian Andrzej Siewior wrote:
> On 2021-03-17 15:38:52 [+0100], Thomas Gleixner wrote:
>> thread(irq_A)
>> irq_handler(A)
>> spin_lock(&foo->lock);
>>
>> interrupt(irq_B)
>> irq_handler(B)
>> spin_lock(&foo->lock);
>
> It will not because both threads will wake_up(thread). It is an issue if
> - if &foo->lock is shared between a hrtimer and threaded-IRQ
> - if &foo->lock is shared between a non-threaded and thread-IRQ
> - if &foo->lock is shared between a printk() in hardirq context and
> thread-IRQ as I learned today.
That's the point and it's entirely clear from the above: A is thread
context and B is hard interrupt context and if the lock is shared then
it's busted. Otherwise we would not have this discussion at all.
next prev parent reply other threads:[~2021-03-17 16:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 14:38 Thomas Gleixner
2021-03-17 14:48 ` Sebastian Andrzej Siewior
2021-03-17 16:09 ` Thomas Gleixner [this message]
2021-03-17 16:23 ` Johan Hovold
2021-03-18 8:51 ` Sebastian Andrzej Siewior
2021-03-20 23:19 ` [tip: irq/urgent] " tip-bot2 for Thomas Gleixner
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