Commit 13684e96 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Andrew Morton
Browse files

lib: dhry: fix unstable smp_processor_id(_) usage 

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: d5528cc1 ("lib: add Dhrystone benchmark test")
Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Reported-by: default avatarTobias Klausmann <klausman@schwarzvogel.de>
  Link: https://bugzilla.kernel.org/show_bug.cgi?id=217179


Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent d2e44a50

lib/dhry_run.c

+4 −2
Original line number Diff line number Diff line
@@ -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