diff options
| author | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2024-07-29 11:55:04 +0100 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2024-07-29 15:32:37 +0200 |
| commit | 0f7ced7d620ecc7a986843d6aeec41cce3116f41 (patch) | |
| tree | 445605a8406266b71711bbeb059666ae973d795c /arch | |
| parent | 8400291e289ee6b2bf9779ff1c83a291501f017b (diff) | |
x86/aperfmperf: Fix deadlock on cpu_hotplug_lock
The broken patch results in a call to init_freq_invariance_cppc() in a CPU
hotplug handler in both the path for initially present CPUs and those
hotplugged later. That function includes a one time call to
amd_set_max_freq_ratio() which in turn calls freq_invariance_enable() that has
a static_branch_enable() which takes the cpu_hotlug_lock which is already
held.
Avoid the deadlock by using static_branch_enable_cpuslocked() as the lock will
always be already held. The equivalent path on Intel does not already hold
this lock, so take it around the call to freq_invariance_enable(), which
results in it being held over the call to register_syscall_ops, which looks to
be safe to do.
Fixes: c1385c1f0ba3 ("ACPI: processor: Simplify initial onlining to use same path for cold and hotplug")
Closes: https://lore.kernel.org/all/CABXGCsPvqBfL5hQDOARwfqasLRJ_eNPBbCngZ257HOe=xbWDkA@mail.gmail.com/
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240729105504.2170-1-Jonathan.Cameron@huawei.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/aperfmperf.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c index b3fa61d45352..0b69bfbf345d 100644 --- a/arch/x86/kernel/cpu/aperfmperf.c +++ b/arch/x86/kernel/cpu/aperfmperf.c @@ -306,7 +306,7 @@ static void freq_invariance_enable(void) WARN_ON_ONCE(1); return; } - static_branch_enable(&arch_scale_freq_key); + static_branch_enable_cpuslocked(&arch_scale_freq_key); register_freq_invariance_syscore_ops(); pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio); } @@ -323,8 +323,10 @@ static void __init bp_init_freq_invariance(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) return; - if (intel_set_max_freq_ratio()) + if (intel_set_max_freq_ratio()) { + guard(cpus_read_lock)(); freq_invariance_enable(); + } } static void disable_freq_invariance_workfn(struct work_struct *work) |