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From: Andy Lutomirski <luto@amacapital.net>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/5] New way to track mce notifier chain actions
Date: Wed, 12 Feb 2020 21:52:39 -0800	[thread overview]
Message-ID: <CALCETrXx7ah9c=TYGm3ZXvwUnoJkDHP1vbuqaudih9fik5W9_A@mail.gmail.com> (raw)
In-Reply-To: <20200212230815.GA3217@agluck-desk2.amr.corp.intel.com>

On Wed, Feb 12, 2020 at 3:08 PM Luck, Tony <tony.luck@intel.com> wrote:
>
> On Wed, Feb 12, 2020 at 12:46:47PM -0800, Tony Luck wrote:
> > Part 4 is where things are interesting and need a great deal more
> > thought.  A bunch of things on the chain return NOTIFY_STOP which
> > prevents anything else on the chain from being run.  For the moment
> > I ignored that semantic and added code everywhere to set the BIT
> > even though nobody else will see it.  This is because I think at
> > least some of them should NOT be NOTIFY_STOP.
>
> NOTIFY_STOP is just one mechanism for preventing every function
> on the mce chain from reporting an error.
>
> The other bit I'd like to reconsider is edac_get_report_status().
> Back in the day we seemed to be paranoid about reporting the same
> error more than once via all the different reporting mechanisms.
>
> Since then I've had to track down numerous "Why didn't this error
> get reported?" questions that frequently resolved to "It was reported,
> but not in the place that you expected".
>
> So now my attitude is "Let's just log it everywhere in so that
> whatever log the user is checking, they'll find the error"

I HATE notifier chains for exceptions, and I REALLY HATE NOTIFY_STOP.
I don't suppose we could rig something up so that they are simply
notifiers (for MCE and, eventually, for everything) and just outright
prevent them from modifying the processing?

As an example that particularly bothers me, do_debug():

        if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
                                                        SIGTRAP) == NOTIFY_STOP)
                goto exit;

There is all kind of garbage hidden in there, and it's mostly
somewhere between slightly buggy and violently buggy.  All this crap
should be open-coded.

  reply	other threads:[~2020-02-13  5:52 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 20:46 [RFC PATCH 0/5] New way to track mce notifier chain actions Tony Luck
2020-02-12 20:46 ` [PATCH 1/5] x86/mce: Rename "first" function as "early" Tony Luck
2020-02-12 20:46 ` [PATCH 2/5] x86/mce: Convert corrected error collector to use mce notifier Tony Luck
2020-02-12 20:46 ` [PATCH 3/5] x86/mce: Add new "handled" field to "struct mce" Tony Luck
2020-02-13 16:56   ` Borislav Petkov
2020-02-13 22:09     ` Luck, Tony
2020-02-14  8:50       ` Borislav Petkov
2020-02-12 20:46 ` [PATCH 4/5] x86/mce: Fix all mce notifiers to update the mce->handled bitmask Tony Luck
2020-02-13 17:03   ` Borislav Petkov
2020-02-13 22:19     ` Luck, Tony
2020-02-13 22:27       ` Andy Lutomirski
2020-02-13 23:08         ` Luck, Tony
2020-02-14  9:02           ` Borislav Petkov
2020-02-14  0:18         ` Thomas Gleixner
2020-02-14  8:59       ` Borislav Petkov
2020-02-12 20:46 ` [PATCH 5/5] x86/mce: Change default mce logger to check mce->handled Tony Luck
2020-02-13 17:08   ` Borislav Petkov
2020-02-13 22:27     ` Luck, Tony
2020-02-14  9:05       ` Borislav Petkov
2020-02-12 23:08 ` [RFC PATCH 0/5] New way to track mce notifier chain actions Luck, Tony
2020-02-13  5:52   ` Andy Lutomirski [this message]
2020-02-13  6:09     ` Borislav Petkov
2020-02-13 16:05       ` Andy Lutomirski
2020-02-14 22:27 ` [PATCH v2 0/7] " Tony Luck
2020-02-14 22:27   ` [PATCH v2 1/7] x86/mce: Rename "first" function as "early" Tony Luck
2020-04-15  9:49     ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-02-14 22:27   ` [PATCH v2 2/7] x86/mce: Convert corrected error collector to use mce notifier Tony Luck
2020-04-15  9:49     ` [tip: ras/core] x86/mce: Convert the CEC to use the MCE notifier tip-bot2 for Tony Luck
2020-02-14 22:27   ` [PATCH v2 3/7] x86/mce: Add new "kflags" field to "struct mce" Tony Luck
2020-04-15  9:49     ` [tip: ras/core] x86/mce: Add a struct mce.kflags field tip-bot2 for Tony Luck
2020-04-15 18:19       ` Luck, Tony
2020-04-15 18:36         ` Borislav Petkov
2020-04-15 19:58           ` [PATCH] x86/mce: Drop bogus comment about mce.kflags Luck, Tony
2020-04-17  9:21             ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-04-20  8:06       ` [tip: ras/core] x86/mce: Add a struct mce.kflags field Christoph Hellwig
2020-04-20  8:42         ` Borislav Petkov
2020-02-14 22:27   ` [PATCH v2 4/7] x86/mce: Fix all mce notifiers to update the mce->kflags bitmask Tony Luck
2020-04-07  8:21     ` Borislav Petkov
2020-04-15  9:49     ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-02-14 22:27   ` [PATCH v2 5/7] x86/mce: Change default mce logger to check mce->kflags Tony Luck
2020-04-07 11:10     ` Borislav Petkov
2020-04-07 16:43       ` Luck, Tony
2020-04-07 19:37         ` Borislav Petkov
2020-04-07 19:44           ` Luck, Tony
2020-04-15  9:49     ` [tip: ras/core] x86/mce: Change default MCE " tip-bot2 for Tony Luck
2020-02-14 22:27   ` [PATCH v2 6/7] x86/mce: Add mce=print_all option Tony Luck
2020-04-15  9:49     ` [tip: ras/core] " tip-bot2 for Tony Luck
2020-02-14 22:27   ` [PATCH v2 7/7] x86/mce: Drop the EDAC report status checks Tony Luck
2020-04-15  9:49     ` [tip: ras/core] EDAC: " tip-bot2 for Tony Luck
2020-04-07 16:34 ` [PATCH 0/9 v3] New way to track mce notifier chain actions Borislav Petkov
2020-04-07 16:34   ` [PATCH 1/9] x86/mce/amd, edac: Remove report_gart_errors Borislav Petkov
2020-04-15  9:49     ` [tip: ras/core] " tip-bot2 for Borislav Petkov
2020-04-07 16:34   ` [PATCH 2/9] x86/mce: Rename "first" function as "early" Borislav Petkov
2020-04-07 16:34   ` [PATCH 3/9] x86/mce: Convert the CEC to use the MCE notifier Borislav Petkov
2020-04-07 16:34   ` [PATCH 4/9] x86/mce: Add a struct mce.kflags field Borislav Petkov
2020-04-07 16:34   ` [PATCH 5/9] x86/mce: Fix all mce notifiers to update the mce->kflags bitmask Borislav Petkov
2020-04-07 16:34   ` [PATCH 6/9] x86/mce: Change default MCE logger to check mce->kflags Borislav Petkov
2020-04-07 16:34   ` [PATCH 7/9] x86/mce: Add mce=print_all option Borislav Petkov
2020-04-07 16:34   ` [PATCH 8/9] EDAC: Drop the EDAC report status checks Borislav Petkov
2020-04-07 16:34   ` [PATCH 9/9] x86/mce: Fixup exception only for the correct MCEs Borislav Petkov
2020-04-15  9:49     ` [tip: ras/core] " tip-bot2 for Borislav Petkov
2020-04-07 19:53   ` [PATCH 0/9 v3] New way to track mce notifier chain actions Luck, Tony
2020-04-07 19:56     ` Borislav Petkov

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