+ lib-dhry-fix-unstable-smp_processor_id_-usage.patch added to mm-hotfixes-unstable branch

+ lib-dhry-fix-unstable-smp_processor_id_-usage.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: lib: dhry: fix unstable smp_processor_id(_) usage
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     lib-dhry-fix-unstable-smp_processor_id_-usage.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-dhry-fix-unstable-smp_processor_id_-usage.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Geert Uytterhoeven <geert+renesas@glider.be>
Subject: lib: dhry: fix unstable smp_processor_id(_) usage
Date: Wed, 15 Mar 2023 15:28:17 +0100

When running the in-kernel Dhrystone benchmark with
CONFIG_DEBUG_PREEMPT=y:

    BUG: using smp_processor_id() in preemptible [00000000] code: bash/938

Fix this by not using smp_processor_id() directly, but instead wrapping
the whole benchmark inside a get_cpu()/put_cpu() pair.  This makes sure
the whole benchmark is run on the same CPU core, and the reported values
are consistent.

Link: https://lkml.kernel.org/r/b0d29932bb24ad82cea7f821e295c898e9657be0.1678890070.git.geert+renesas@glider.be
Fixes: d5528cc16893f1f6 ("lib: add Dhrystone benchmark test")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reported-by: Tobias Klausmann <klausman@schwarzvogel.de>
  Link: https://bugzilla.kernel.org/show_bug.cgi?id=217179
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/dhry_run.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/lib/dhry_run.c~lib-dhry-fix-unstable-smp_processor_id_-usage
+++ a/lib/dhry_run.c
@@ -31,6 +31,7 @@ MODULE_PARM_DESC(iterations,
 
 static void dhry_benchmark(void)
 {
+	unsigned int cpu = get_cpu();
 	int i, n;
 
 	if (iterations > 0) {
@@ -45,9 +46,10 @@ static void dhry_benchmark(void)
 	}
 
 report:
+	put_cpu();
 	if (n >= 0)
-		pr_info("CPU%u: Dhrystones per Second: %d (%d DMIPS)\n",
-			smp_processor_id(), n, n / DHRY_VAX);
+		pr_info("CPU%u: Dhrystones per Second: %d (%d DMIPS)\n", cpu,
+			n, n / DHRY_VAX);
 	else if (n == -EAGAIN)
 		pr_err("Please increase the number of iterations\n");
 	else
_

Patches currently in -mm which might be from geert+renesas@glider.be are

lib-dhry-fix-unstable-smp_processor_id_-usage.patch