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    SubjectRe: [PATCH -v3] x86, MCE: Drop the default decoding notifier


    On 04/14/2011 11:16 AM, Borislav Petkov wrote:
    > On Thu, Apr 14, 2011 at 11:04:43AM -0400, Prarit Bhargava wrote:
    >
    >>
    >> On 04/14/2011 11:00 AM, Borislav Petkov wrote:
    >>
    >>> On Wed, Apr 13, 2011 at 01:37:05PM -0400, Borislav Petkov wrote:
    >>>
    >>>
    >>>> In the worst case, we will report 32 CEs before panicking. For that case
    >>>> we either do printk_once as Tony suggested or we ratelimit it. I'll
    >>>> update the patch.
    >>>>
    >>>>
    >>> Ok, how about the following, I ratelimit the printk to the default of 10
    >>> messages per 5 seconds. I've also got the hardware MCE injection patches
    >>> ready and will do some testing with them.
    >>>
    >>>
    >> See my previous email ;) I think just putting in a printk_once after
    >> the CE call to print_mce() in mce_panic() might be better? At least
    >> that way we get the --ascii message for *EVERY* UC which IMO would be
    >> nice...
    >>
    > Are you sure? printk_once() is, as its name says, a one-time thing and
    > it is implemented that way - a static bool counter which is once set and
    > that's it. I.e., the "--ascii" message will be printed only once for the
    > system's lifetime.
    >

    Oops ... I may have confused you because what I did was subtle. I
    really should have explicitly pointed out what I did. Sorry, my bad.

    From my patch (sorry for the cut-and-paste):

    @@ -239,7 +227,10 @@ static void print_mce(struct mce *m)
    * 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);
    + 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 above through 'mcelog --ascii' "
    + "to decode.\n");
    }

    This, of course, only outputs during UCs.

    and

    @@ -289,6 +280,8 @@ static void mce_panic(char *msg, struct mce *final,
    char *exp)
    continue;
    if (!(m->status & MCI_STATUS_UC)) {
    print_mce(m);
    + printk_once(KERN_EMERG HW_ERR "MCE Corrected
    Error(s) "
    + "detected.");
    if (!apei_err)
    apei_err = apei_write_mce(m);
    }
    so we'll print "MCE Corrected Error(s)" _once_ if we go through this
    path. Since there is no data to decode with mcelog, a nice little one
    time message is probably the way to go :).

    P.


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