From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: pawandeep oza <oza.contri.linux.kernel@gmail.com>
Cc: akpm@linux-foundation.org, holt@sgi.com, mingo@kernel.org,
sboyd@codeaurora.org, k.khlebnikov@samsung.com,
u.kleine-koenig@pengutronix.de, nicolas.pitre@linaro.org,
linux-arm-kernel@lists.infradead.or,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] machine_power_off: not only local_irq_disable but also do disable preemption
Date: Sat, 5 Jul 2014 19:10:15 +0100 [thread overview]
Message-ID: <20140705181015.GQ21766@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAA-nRyoO_NmrD8aRa3OyVXz4b133Fxi0=biGXTzSPDuSuNJJxQ@mail.gmail.com>
On Sat, Jul 05, 2014 at 10:44:41PM +0530, pawandeep oza wrote:
> process calls sys_reboot and that process then stops other CPUs while those
> CPUs are within a spin_lock() region we can potentially encounter a
> deadlock
> scenario like below.
>
> CPU 0 CPU 1
> ----- -----
> spin_lock(my_lock)
> smp_send_stop()
> <send IPI> handle_IPI()
> disable_preemption/irqs
> while(1);
> <PREEMPT>
> spin_lock(my_lock) <--- Waits forever
Please explain how that <PREEMPT> occurs with IRQs already disabled.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
next parent reply other threads:[~2014-07-05 18:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAA-nRyoO_NmrD8aRa3OyVXz4b133Fxi0=biGXTzSPDuSuNJJxQ@mail.gmail.com>
2014-07-05 18:10 ` Russell King - ARM Linux [this message]
[not found] ` <CAA-nRyp5pPC2qZs7RhAXJdXaK_k4fKNZuq=yRTSTPLQsgPxqxQ@mail.gmail.com>
2014-07-05 19:01 ` [PATCH] machine_power_off: not only local_irq_disable but also do disable preemption Russell King - ARM Linux
[not found] ` <CAA-nRyo2Ts3o_B1jMS8vvLJanf13u=u2WyoqnL8bCF5svOOCew@mail.gmail.com>
2014-07-05 19:26 ` Russell King - ARM Linux
[not found] ` <CAA-nRyqHXCBCzKcK83UnS64f_wKcWObzui2xamt=ayVDKX9zEA@mail.gmail.com>
[not found] ` <CAA-nRyo3T+JLpfE6M260Ws+Ddu4z3TS2fQy5sv_dETMTcYFscQ@mail.gmail.com>
2014-07-06 15:35 ` Russell King - ARM Linux
[not found] ` <CAA-nRyppv-LruJK0NySQ_VGORP1+M1w++=k5rqeiC15Wc6Ks9g@mail.gmail.com>
2014-07-06 17:28 ` Russell King - ARM Linux
[not found] ` <CAA-nRyqaOoXKs9OfaLGObDAG3=Gey+7UoOYdjLUfv45kprqdFg@mail.gmail.com>
2014-07-06 18:42 ` Russell King - ARM Linux
2014-07-05 19:25 ` Russell King - ARM Linux
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