linux-kernel - Re: [PATCH v2] x86/mce/AMD: Use saved threshold block info in interrupt handler

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Date:   Thu, 1 Jun 2017 19:49:51 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <Yazen.Ghannam@....com>
Cc:     linux-edac@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86/mce/AMD: Use saved threshold block info in
 interrupt handler

On Wed, May 31, 2017 at 09:11:55AM -0500, Yazen Ghannam wrote:
> From: Yazen Ghannam <yazen.ghannam@....com>
> 
> In the amd_threshold_interrupt() handler, we loop through every possible
> block in each bank and rediscover the block's address and if it's valid,
> e.g. valid, counter present and not locked. However, we already have the
> address saved in the threshold blocks list for each CPU and bank. The list
> only contains blocks that have passed all the valid checks.
> 
> Besides the redundancy, there's also a smp_call_function* in
> get_block_address() and this causes a warning when servicing the interrupt.
> 
>  WARNING: CPU: 0 PID: 0 at kernel/smp.c:281 smp_call_function_single+0xdd/0xf0
>  ...
>  Call Trace:
>   <IRQ>
>   rdmsr_safe_on_cpu+0x5d/0x90
>   get_block_address.isra.2+0x97/0x100
>   amd_threshold_interrupt+0xae/0x220
>   smp_threshold_interrupt+0x1b/0x40
>   threshold_interrupt+0x89/0x90
> 
> Drop the redundant valid checks and move the overflow check, logging and
> block reset into a separate function.
> 
> Check the first block then iterate over the rest. This procedure is needed
> since the first block is used as the head of the list.
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> ---
> Link:
> https://lkml.kernel.org/r/1495658507-7413-3-git-send-email-Yazen.Ghannam@amd.com
> 
> Link for patch 2:
> https://lkml.kernel.org/r/1495658507-7413-2-git-send-email-Yazen.Ghannam@amd.com
> 
> v1->v2:
> * Drop patch 2 from the first set.
> * Rather than iterating through all blocks in the list, check the first
>   and iterate over the rest. This way we don't need to have an external
>   list_head.
>  
>  arch/x86/kernel/cpu/mcheck/mce_amd.c | 64 ++++++++++++++++++++----------------
>  1 file changed, 35 insertions(+), 29 deletions(-)

Much better!

Applied, thanks.

-- 
Regards/Gruss,
    Boris.

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