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| author | Kan Liang <kan.liang@linux.intel.com> | 2024-09-12 07:50:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2024-09-22 09:03:22 -0700 |
| commit | 673a5009cf2f020dac440cd79e70c4c8b8e20d08 (patch) | |
| tree | 056ea7e9b5d1aecc37892cf9c55aca8b33286b15 /kernel | |
| parent | 88264981f2082248e892a706b2c5004650faac54 (diff) | |
| download | lwn-673a5009cf2f020dac440cd79e70c4c8b8e20d08.tar.gz lwn-673a5009cf2f020dac440cd79e70c4c8b8e20d08.zip | |
perf: Fix topology_sibling_cpumask check warning on ARM
The below 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 never be NULL.
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@canb.auug.org.au>
Closes: https://lore.kernel.org/lkml/20240911153854.240bbc1f@canb.auug.org.au/
Reported-by: Steven Price <steven.price@arm.com>
Closes: https://lore.kernel.org/lkml/1835eb6d-3e05-47f3-9eae-507ce165c3bf@arm.com/
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Steven Price <steven.price@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 0016f5ff9ba2..5afde9f7b52a 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) |