The 'storm' variable points to this_cpu_ptr(&storm_desc). Access the
'stormy_bank_count' field through the 'storm' to avoid calling
this_cpu_*() on the same per-CPU variable twice.

This minor optimization reduces the text size by 16 bytes.

  $ size threshold.o.*
     text	   data	    bss	    dec	    hex	filename
     1395	   1664	      0	   3059	    bf3	threshold.o.old
     1379	   1664	      0	   3043	    be3	threshold.o.new

No functional changes intended.

Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
---
Changes in v5:
  - No changes.

Changes in v4:
  - No changes.

Changes in v3:
  - Collect "Reviewed-by:" from Nikolay & Sohil.

Changes in v2:
  - Collect "Reviewed-by:" from Tony.

 arch/x86/kernel/cpu/mce/threshold.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/threshold.c b/arch/x86/kernel/cpu/mce/threshold.c
index 89e31e1e5c9c..f4a007616468 100644
--- a/arch/x86/kernel/cpu/mce/threshold.c
+++ b/arch/x86/kernel/cpu/mce/threshold.c
@@ -90,7 +90,7 @@ void cmci_storm_end(unsigned int bank)
 	storm->banks[bank].in_storm_mode = false;
 
 	/* If no banks left in storm mode, stop polling. */
-	if (!this_cpu_dec_return(storm_desc.stormy_bank_count))
+	if (!--storm->stormy_bank_count)
 		mce_timer_kick(false);
 }
 
-- 
2.17.1

On Thu, Dec 12, 2024 at 10:00:58PM +0800, Qiuxu Zhuo wrote:
> The 'storm' variable points to this_cpu_ptr(&storm_desc). Access the
> 'stormy_bank_count' field through the 'storm' to avoid calling
> this_cpu_*() on the same per-CPU variable twice.
> 
> This minor optimization reduces the text size by 16 bytes.
> 
>   $ size threshold.o.*
>      text	   data	    bss	    dec	    hex	filename
>      1395	   1664	      0	   3059	    bf3	threshold.o.old
>      1379	   1664	      0	   3043	    be3	threshold.o.new
> 
> No functional changes intended.
> 
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
> Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>

Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>

Thanks,
Yazen

The following commit has been merged into the ras/core branch of tip:

Commit-ID:     64a668fbea1b6ec06ddca66d09cc49352f063342
Gitweb:        https://git.kernel.org/tip/64a668fbea1b6ec06ddca66d09cc49352f063342
Author:        Qiuxu Zhuo <qiuxu.zhuo@intel.com>
AuthorDate:    Thu, 12 Dec 2024 22:00:58 +08:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 30 Dec 2024 19:45:03 +01:00

x86/mce/threshold: Remove the redundant this_cpu_dec_return()

The 'storm' variable points to this_cpu_ptr(&storm_desc). Access the
'stormy_bank_count' field through the 'storm' to avoid calling
this_cpu_*() on the same per-CPU variable twice.

This minor optimization reduces the text size by 16 bytes.

  $ size threshold.o.*
     text	   data	    bss	    dec	    hex	filename
     1395	   1664	      0	   3059	    bf3	threshold.o.old
     1379	   1664	      0	   3043	    be3	threshold.o.new

No functional changes intended.

Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Link: https://lore.kernel.org/r/20241212140103.66964-3-qiuxu.zhuo@intel.com
---
 arch/x86/kernel/cpu/mce/threshold.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/threshold.c b/arch/x86/kernel/cpu/mce/threshold.c
index 89e31e1..f4a0076 100644
--- a/arch/x86/kernel/cpu/mce/threshold.c
+++ b/arch/x86/kernel/cpu/mce/threshold.c
@@ -90,7 +90,7 @@ void cmci_storm_end(unsigned int bank)
 	storm->banks[bank].in_storm_mode = false;
 
 	/* If no banks left in storm mode, stop polling. */
-	if (!this_cpu_dec_return(storm_desc.stormy_bank_count))
+	if (!--storm->stormy_bank_count)
 		mce_timer_kick(false);
 }