linux-kernel - Re: [PATCH v5 04/20] x86/mce/amd: Put list_head in threshold

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Message-ID: <49d90a98-f3fb-4df2-837f-53b109cfcd6d@suse.com>
Date: Mon, 1 Sep 2025 18:41:12 +0300
From: Nikolay Borisov <nik.borisov@...e.com>
To: Yazen Ghannam <yazen.ghannam@....com>, x86@...nel.org,
 Tony Luck <tony.luck@...el.com>, "Rafael J. Wysocki" <rafael@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
 Smita.KoralahalliChannabasappa@....com, Qiuxu Zhuo <qiuxu.zhuo@...el.com>,
 linux-acpi@...r.kernel.org
Subject: Re: [PATCH v5 04/20] x86/mce/amd: Put list_head in threshold_bank



On 8/25/25 20:33, Yazen Ghannam wrote:
> The threshold_bank structure is a container for one or more
> threshold_block structures. Currently, the container has a single
> pointer to the 'first' threshold_block structure which then has a linked
> list of the remaining threshold_block structures.
> 
> This results in an extra level of indirection where the 'first' block is
> checked before iterating over the remaining blocks.
> 
> Remove the indirection by including the head of the block list in the
> threshold_bank structure which already acts as a container for all the
> bank's thresholding blocks.
> 
> Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> Tested-by: Tony Luck <tony.luck@...el.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>



> ---
> 
> Notes:
>      Link:
>      https://lore.kernel.org/r/20250624-wip-mca-updates-v4-8-236dd74f645f@amd.com
>      
>      v4->v5:
>      * No change.
>      
>      v3->v4:
>      * No change.
>      
>      v2->v3:
>      * Added tags from Qiuxu and Tony.
>      
>      v1->v2:
>      * New in v2.
> 
>   arch/x86/kernel/cpu/mce/amd.c | 43 ++++++++++++-------------------------------
>   1 file changed, 12 insertions(+), 31 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
> index 580682af432d..54f02bda75aa 100644
> --- a/arch/x86/kernel/cpu/mce/amd.c
> +++ b/arch/x86/kernel/cpu/mce/amd.c
> @@ -241,7 +241,8 @@ struct threshold_block {
>   
>   struct threshold_bank {
>   	struct kobject		*kobj;
> -	struct threshold_block	*blocks;
> +	/* List of threshold blocks within this MCA bank. */
> +	struct list_head	miscj;
>   };
>   
>   static DEFINE_PER_CPU(struct threshold_bank **, threshold_banks);
> @@ -902,9 +903,9 @@ static void log_and_reset_block(struct threshold_block *block)
>    */
>   static void amd_threshold_interrupt(void)
>   {
> -	struct threshold_block *first_block = NULL, *block = NULL, *tmp = NULL;
> -	struct threshold_bank **bp = this_cpu_read(threshold_banks);
> +	struct threshold_bank **bp = this_cpu_read(threshold_banks), *thr_bank;
>   	unsigned int bank, cpu = smp_processor_id();
> +	struct threshold_block *block, *tmp;
>   
>   	/*
>   	 * Validate that the threshold bank has been initialized already. The
> @@ -918,16 +919,11 @@ static void amd_threshold_interrupt(void)
>   		if (!(per_cpu(bank_map, cpu) & BIT_ULL(bank)))
>   			continue;

So the following diff can be applied ontop of this hunk to simplify the function even further:


diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 5c4eb28c3ac9..b35e74292f58 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -932,7 +932,7 @@ static void amd_threshold_interrupt(void)
  {
         struct threshold_block *first_block = NULL, *block = NULL, *tmp = NULL;
         struct threshold_bank **bp = this_cpu_read(threshold_banks);
-       unsigned int bank, cpu = smp_processor_id();
+       unsigned int bank;
  
         /*
          * Validate that the threshold bank has been initialized already. The
@@ -943,7 +943,7 @@ static void amd_threshold_interrupt(void)
                 return;
  
         for (bank = 0; bank < this_cpu_read(mce_num_banks); ++bank) {
-               if (!(per_cpu(bank_map, cpu) & BIT_ULL(bank)))
+               if (!(x86_this_cpu_test_bit(bank, bank_map)))
                         continue;
  
                 first_block = bp[bank]->blocks;


Will you integrate it (Boris) at merge time or should I send a patch now (or later) ?


<snip>