mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-01-17 10:26:09 +00:00
0f7ced7d62
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