From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755981Ab1DMOBj (ORCPT ); Wed, 13 Apr 2011 10:01:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4430 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753370Ab1DMOBi (ORCPT ); Wed, 13 Apr 2011 10:01:38 -0400 Message-ID: <4DA5ACB2.1070505@redhat.com> Date: Wed, 13 Apr 2011 10:01:22 -0400 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100505 Fedora/3.0.4-2.el6 Thunderbird/3.0.4 MIME-Version: 1.0 To: Borislav Petkov CC: linux-kernel@vger.kernel.org, Borislav Petkov , Russ Anderson , "Luck, Tony" , "dzickus@redhat.com" , "mstowe@redhat.com" , "dnelson@redhat.com" , "rja@americas.sgi.com" Subject: Re: [PATCH 2/3] x86, MCE: Drop default decoding notifier References: <20110413132409.GB1900@gere.osrc.amd.com> <1302701810-2471-2-git-send-email-bp@amd64.org> In-Reply-To: <1302701810-2471-2-git-send-email-bp@amd64.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/13/2011 09:36 AM, Borislav Petkov wrote: > From: Borislav Petkov > > The default notifier doesn't make a lot of sense to call in the > correctable errors case. Drop it and emit the mcelog decoding hint only > in the uncorrectable errors case and when no notifier is registered. > > Signed-off-by: Borislav Petkov > --- > arch/x86/include/asm/mce.h | 4 ++-- > arch/x86/kernel/cpu/mcheck/mce.c | 26 +++++++++----------------- > 2 files changed, 11 insertions(+), 19 deletions(-) > > +extern atomic_t mce_decoders; > + Boris, I don't think we need to do this. I think we can use the existing notifier chain tools to do this check for us ... *untested and uncompiled* patch below. * Print out human-readable details about the MCE error, > * (if the CPU has an implementation for that) > */ > - atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m); > + if (!atomic_read(&mce_decoders)) { > + pr_emerg(HW_ERR "No human readable MCE decoding support on this CPU type.\n"); > + pr_emerg(HW_ERR "Run the above through 'mcelog --ascii' to decode.\n"); I thought we didn't want these lines at all for CE errors? > + } else > + atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m); > } > > #define PANIC_TIMEOUT 5 /* 5 seconds */ > @@ -589,7 +582,8 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b) > */ > if (!(flags & MCP_DONTLOG) && !mce_dont_log_ce) { > mce_log(&m); > - atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, &m); > + if (atomic_read(&mce_decoders)) > + atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, &m); > } > > /* > @@ -1721,8 +1715,6 @@ __setup("mce", mcheck_enable); > > int __init mcheck_init(void) > { > - atomic_notifier_chain_register(&x86_mce_decoder_chain, &mce_dec_nb); > - > mcheck_intel_therm_init(); > > return 0; Again, this patch has not been tested or compiled against latest upstream. I have quickly tested it against RHEL6 (2.6.32,33,34,35,36,38,39 based) and confirmed that I don't see the messages for CEs. I have NOT fully tested to see what happens when I add in a "dummy" notifier to see if the messages are not printed. diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 3385ea2..b10a1f4 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -100,25 +100,12 @@ static int cpu_missing; /* * CPU/chipset specific EDAC code can register a notifier call here to print - * MCE errors in a human-readable form. + * MCE errors in a human-readable form. Notifiers must return NOTIFY_STOP + * upon completion. */ ATOMIC_NOTIFIER_HEAD(x86_mce_decoder_chain); EXPORT_SYMBOL_GPL(x86_mce_decoder_chain); -static int default_decode_mce(struct notifier_block *nb, unsigned long val, - void *data) -{ - pr_emerg(HW_ERR "No human readable MCE decoding support on this CPU type.\n"); - pr_emerg(HW_ERR "Run the message through 'mcelog --ascii' to decode.\n"); - - return NOTIFY_STOP; -} - -static struct notifier_block mce_dec_nb = { - .notifier_call = default_decode_mce, - .priority = -1, -}; - /* MCA banks polled by the period polling timer for corrected events */ DEFINE_PER_CPU(mce_banks_t, mce_poll_banks) = { [0 ... BITS_TO_LONGS(MAX_NR_BANKS)-1] = ~0UL @@ -212,6 +199,8 @@ void mce_log(struct mce *mce) static void print_mce(struct mce *m) { + int ret; + pr_emerg(HW_ERR "CPU %d: Machine Check Exception: %Lx Bank %d: %016Lx\n", m->extcpu, m->mcgstatus, m->bank, m->status); @@ -236,10 +225,13 @@ static void print_mce(struct mce *m) m->cpuvendor, m->cpuid, m->time, m->socketid, m->apicid); /* - * Print out human-readable details about the MCE error, - * (if the CPU has an implementation for that) + * Output a message if the CPU has human-readable information for + * unhandled UC errors */ - atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m); + ret = atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, &m); + if ((ret != NOTIFY_STOP) && (m->status & MCI_STATUS_UC)) + pr_emerg(HW_ERR "Run the message through 'mcelog --ascii' " + "to decode.\n"); } #define PANIC_TIMEOUT 5 /* 5 seconds */ @@ -589,8 +581,8 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b) */ if (!(flags & MCP_DONTLOG) && !mce_dont_log_ce) { mce_log(&m); - atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, &m); - add_taint(TAINT_MACHINE_CHECK); + atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, + &m); } /* @@ -1722,8 +1714,6 @@ __setup("mce", mcheck_enable); int __init mcheck_init(void) { - atomic_notifier_chain_register(&x86_mce_decoder_chain, &mce_dec_nb); - mcheck_intel_therm_init(); return 0;