From: Philby John <pjohn@mvista.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: linux-mips@linux-mips.org, Artem Bityutskiy <dedekind1@gmail.com>,
linux-mtd@lists.infradead.org,
David Daney <ddaney@caviumnetworks.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mtd: Fix bug using smp_processor_id() in preemptible ubi_bgt1d kthread
Date: Tue, 15 Jun 2010 17:56:34 +0530 [thread overview]
Message-ID: <1276604794.19810.3.camel@localhost.localdomain> (raw)
In-Reply-To: <20100614150425.GC9550@shareable.org>
Hello Jamie,
On Mon, 2010-06-14 at 16:04 +0100, Jamie Lokier wrote:
> Philby John wrote:
> > mtd: Fix bug using smp_processor_id() in preemptible ubi_bgt1d kthread
> >
> > On a MIPS Cavium Octeon CN5020 when trying to create a UBI volume,
> > on the NOR flash, the kernel thread ubi_bgt1d calls
> > cfi_amdstd_write_buffers() --> do_write_buffer() -->
> > INVALIDATE_CACHE_UDELAY --> __udelay(). Its __udelay() that calls
> > smp_processor_id() in preemptible code, which you are not supposed to.
> > Fix the problem by disabling preemption.
>
> The MTD code just calls udelay().
> Are you sure it isn't permitted to call udelay() from preemptible code?
> I think it is fine.
>
> Perhaps MIPS udelay() should be disabling preemption itself, or
> (as x86 does) using raw_smp_processor_id() instead?
Sorry for the noise. I now find that raw_smp_processor_id() has been
implemented specific to MIPS in the latest kernel, I was using 2.6.32.
Thanks and regards,
Philby
prev parent reply other threads:[~2010-06-15 12:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-14 11:04 [PATCH] mtd: Fix bug using smp_processor_id() in preemptible ubi_bgt1d kthread Philby John
2010-06-14 15:04 ` Jamie Lokier
2010-06-14 15:37 ` Philby John
2010-06-14 16:40 ` Philby John
2010-06-15 12:26 ` Philby John [this message]
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