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 <[email protected]>
Closes: https://lore.kernel.org/lkml/[email protected]/
Reported-by: Steven Price <[email protected]>
Closes: https://lore.kernel.org/lkml/[email protected]/
Signed-off-by: Kan Liang <[email protected]>
Tested-by: Steven Price <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions