__setup() handlers should return 1 to obsolete_checksetup() in
init/main.c to indicate that the boot option has been handled.
A return of 0 causes the boot option/value to be listed as an Unknown
kernel parameter and added to init's (limited) argument or environment
strings. Also, error return codes don't mean anything to
obsolete_checksetup() -- only non-zero (usually 1) or zero.
So return 1 from nmi_debug_setup().
Fixes: 1e1030dccb10 ("sh: nmi_debug support.")
Signed-off-by: Randy Dunlap <rdunlap(a)infradead.org>
Reported-by: Igor Zhbanov <izh1979(a)gmail.com>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Cc: John Paul Adrian Glaubitz <glaubitz(a)physik.fu-berlin.de>
Cc: Yoshinori Sato <ysato(a)users.sourceforge.jp>
Cc: Rich Felker <dalias(a)libc.org>
Cc: linux-sh(a)vger.kernel.org
Cc: stable(a)vger.kernel.org
---
v2: add more Cc's;
refresh and resend;
v3: add Arnd to Cc: list
v4: update Cc: list, refresh & resend
arch/sh/kernel/nmi_debug.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -- a/arch/sh/kernel/nmi_debug.c b/arch/sh/kernel/nmi_debug.c
--- a/arch/sh/kernel/nmi_debug.c
+++ b/arch/sh/kernel/nmi_debug.c
@@ -49,7 +49,7 @@ static int __init nmi_debug_setup(char *
register_die_notifier(&nmi_debug_nb);
if (*str != '=')
- return 0;
+ return 1;
for (p = str + 1; *p; p = sep + 1) {
sep = strchr(p, ',');
@@ -70,6 +70,6 @@ static int __init nmi_debug_setup(char *
break;
}
- return 0;
+ return 1;
}
__setup("nmi_debug", nmi_debug_setup);
From: Tero Kristo <tero.kristo(a)linux.intel.com>
The hwlatd tracer will end up starting multiple per-cpu threads with
the following script:
#!/bin/sh
cd /sys/kernel/debug/tracing
echo 0 > tracing_on
echo hwlat > current_tracer
echo per-cpu > hwlat_detector/mode
echo 100000 > hwlat_detector/width
echo 200000 > hwlat_detector/window
echo 1 > tracing_on
To fix the issue, check if the hwlatd thread for the cpu is already
running, before starting a new one. Along with the previous patch, this
avoids running multiple instances of the same CPU thread on the system.
Link: https://lore.kernel.org/all/20230302113654.2984709-1-tero.kristo@linux.inte…
Link: https://lkml.kernel.org/r/20230310100451.3948583-3-tero.kristo@linux.intel.…
Cc: stable(a)vger.kernel.org
Fixes: f46b16520a087 ("trace/hwlat: Implement the per-cpu mode")
Signed-off-by: Tero Kristo <tero.kristo(a)linux.intel.com>
Acked-by: Daniel Bristot de Oliveira <bristot(a)kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
---
kernel/trace/trace_hwlat.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index edc26dc22c3f..c4945f8adc11 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -492,6 +492,10 @@ static int start_cpu_kthread(unsigned int cpu)
{
struct task_struct *kthread;
+ /* Do not start a new hwlatd thread if it is already running */
+ if (per_cpu(hwlat_per_cpu_data, cpu).kthread)
+ return 0;
+
kthread = kthread_run_on_cpu(kthread_fn, NULL, cpu, "hwlatd/%u");
if (IS_ERR(kthread)) {
pr_err(BANNER "could not start sampling thread\n");
--
2.39.1