The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: 4e340f66f76b36003646165130fd7e3de5219d7f
Gitweb: https://git.kernel.org/tip/4e340f66f76b36003646165130fd7e3de5219d7f
Author: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
AuthorDate: Thu, 12 Sep 2024 07:50:25 -07:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Thu, 19 Sep 2024 11:51:50 +02:00
perf/core: Fix topology_sibling_cpumask() check warning on ARM
The following warning is triggered when building with ARM
multi_v7_defconfig:
kernel/events/core.c: In function 'perf_event_setup_cpumask':
kernel/events/core.c:14012:13: warning: the comparison will always evaluate as 'true' for the address of 'thread_sibling' will never be NULL [-Waddress]
14012 | if (!topology_sibling_cpumask(cpu)) {
The perf_event_init_cpu() may be invoked at the early boot stage, while
the topology_*_cpumask hasn't been initialized yet. The check is to
specially handle the case, and initialize the perf_online_<domain>_masks
on the boot CPU.
x86 uses a per-CPU cpumask pointer, which could be NULL at the early
boot stage. However, ARM uses a global variable, which will
never be NULL.
To work around the warning, use perf_online_mask as an indicator instead.
Only initialize the perf_online_<domain>_masks when perf_online_mask is empty.
Fix a typo as well.
Fixes: 4ba4f1afb6a9 ("perf: Generic hotplug support for a PMU with a scope")
Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Reported-by: Steven Price <steven.price@xxxxxxx>
Tested-by: Steven Price <steven.price@xxxxxxx>
Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240912145025.1574448-1-kan.liang@xxxxxxxxxxxxxxx
---
kernel/events/core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4f03eb9..c5b4fba 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -14002,21 +14002,19 @@ static void perf_event_setup_cpumask(unsigned int cpu)
struct cpumask *pmu_cpumask;
unsigned int scope;
- cpumask_set_cpu(cpu, perf_online_mask);
-
/*
* Early boot stage, the cpumask hasn't been set yet.
* The perf_online_<domain>_masks includes the first CPU of each domain.
- * Always uncondifionally set the boot CPU for the perf_online_<domain>_masks.
+ * Always unconditionally set the boot CPU for the perf_online_<domain>_masks.
*/
- if (!topology_sibling_cpumask(cpu)) {
+ if (cpumask_empty(perf_online_mask)) {
for (scope = PERF_PMU_SCOPE_NONE + 1; scope < PERF_PMU_MAX_SCOPE; scope++) {
pmu_cpumask = perf_scope_cpumask(scope);
if (WARN_ON_ONCE(!pmu_cpumask))
continue;
cpumask_set_cpu(cpu, pmu_cpumask);
}
- return;
+ goto end;
}
for (scope = PERF_PMU_SCOPE_NONE + 1; scope < PERF_PMU_MAX_SCOPE; scope++) {
@@ -14031,6 +14029,8 @@ static void perf_event_setup_cpumask(unsigned int cpu)
cpumask_any_and(pmu_cpumask, cpumask) >= nr_cpu_ids)
cpumask_set_cpu(cpu, pmu_cpumask);
}
+end:
+ cpumask_set_cpu(cpu, perf_online_mask);
}
int perf_event_init_cpu(unsigned int cpu)
|