From: Keith Owens <kaos@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [patch/rfc] mca ia64_log_print() race
Date: Thu, 29 Jan 2004 04:31:21 +0000 [thread overview]
Message-ID: <7316.1075350681@kao2.melbourne.sgi.com> (raw)
In-Reply-To: <Pine.LNX.4.30.0401281942340.18291-100000@cleomedes.llnl.gov>
On Wed, 28 Jan 2004 19:58:33 -0800 (PST),
Jim Garlick <garlick@llnl.gov> wrote:
>We have been exercising some of the MCA code on the bench with an instrumented
>DIMM that can generate single and multibit errors and found that fairly
>frequently the kernel would crash in the process of handling CPE's.
>
>The following patch addresses what we think is a race on ia64_state_log
>that occurs when CPE's occur back to back (as happens with our crude error
>generator, probably more than in nature), possibly exacerbated by configuring
>a slow serial console.
>
>diff -u -r1.4.2.1.4.10 -r1.4.2.1.4.15
>--- arch/ia64/kernel/mca.c 26 Jan 2004 21:18:49 -0000 1.4.2.1.4.10
>+++ arch/ia64/kernel/mca.c 29 Jan 2004 01:37:42 -0000 1.4.2.1.4.15
>@@ -2397,7 +2451,9 @@
> ia64_log_print(int sal_info_type, prfunc_t prfunc)
> {
> int platform_err = 0;
>+ int s;
What is 's' used for?
>
>+ IA64_LOG_LOCK(sal_info_type);
> switch(sal_info_type) {
> case SAL_INFO_TYPE_MCA:
> prfunc("+CPU %d: SAL log contains MCA error record\n", smp_processor_id());
>@@ -2421,6 +2477,7 @@
> prfunc("+MCA UNKNOWN ERROR LOG (UNIMPLEMENTED)\n");
> break;
> }
>+ IA64_LOG_UNLOCK(sal_info_type);
> return platform_err;
> }
That entire chunk of code has always been racy. It is not safe to call
prfunc (printk) for any MCA or INIT events, it can deadlock and/or
break - MCA/INIT is not irq safe. All the printing in mca.c needs to
be cleaned up.
next prev parent reply other threads:[~2004-01-29 4:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-29 3:58 [patch/rfc] mca ia64_log_print() race Jim Garlick
2004-01-29 4:31 ` Keith Owens [this message]
2004-01-29 15:41 ` Jim Garlick
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