From: Julien Grall <julien.grall@arm.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: Philip Elcan <pelcan@codeaurora.org>,
Wei Liu <wei.liu2@citrix.com>, Wei Chen <Wei.Chen@arm.com>,
Vikram Sethi <vikrams@codeaurora.org>,
Steve Capper <Steve.Capper@arm.com>,
xen-devel <xen-devel@lists.xensource.com>,
Shannon Zhao <shannon.zhao@linaro.org>,
Shanker Donthineni <shankerd@codeaurora.org>
Subject: Re: [PATCH] arm/acpi: Fix the deadlock in function vgic_lock_rank()
Date: Wed, 1 Jun 2016 11:49:27 +0100 [thread overview]
Message-ID: <574EBDB7.2000806@arm.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1606011018350.3896@sstabellini-ThinkPad-X260>
Hi Stefano,
On 01/06/16 10:54, Stefano Stabellini wrote:
>> spin_is_locked does not work as you expect. The function will not tell you if
>> the lock was taken by the current CPU, but if the lock was taken by *a* CPU.
>>
>> It would be possible to have CPU A calling this function and have CPU B with
>> the lock taken. So the data structure would be accessed by 2 CPUs
>> concurrently, which is unsafe.
>
> Damn, you are right. I don't think we have a spin_lock function which
> tells us if the spin_lock was taken by us.
Unfortunately not.
> The only other option I see would be duplicating route_irq_to_guest and
> gic_route_irq_to_guest, introducing a second version of those functions
> which assume that the rank lock was already taken. Very very ugly. I'll
> just revert the commit and wait for better patches from Shannon.
I am working on a patch series to decouple IRQ configuration and
routing. It should be ready soon.
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-06-01 10:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-27 0:39 [PATCH] arm/acpi: Fix the deadlock in function vgic_lock_rank() Shanker Donthineni
2016-05-27 13:56 ` Julien Grall
2016-05-30 13:16 ` Stefano Stabellini
2016-05-30 19:45 ` Julien Grall
2016-05-31 0:55 ` Shannon Zhao
2016-05-31 9:40 ` Stefano Stabellini
2016-05-31 10:11 ` Julien Grall
2016-06-01 9:54 ` Stefano Stabellini
2016-06-01 10:49 ` Julien Grall [this message]
2016-06-01 13:55 ` Shannon Zhao
2016-05-31 11:37 ` Wei Liu
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