Re: [PATCH RESEND] powercap: intel_rapl: Fix kernel panic during PMU unbind

[Abel Vesa]

On 26-08-22 15:16:57, Sumeet Pawnikar wrote:
> From: Sumeet Pawnikar <sumeet4linux@xxxxxxxxx>
> 
> rapl_package_add_pmu() fails internally at perf_pmu_register(),
> and rapl_pmu_update() leaves the global rapl_pmu.pmu structure
> zero-initialized via memset and returns an error. But any
> previously probed packages retain has_pmu = true.
> 
> When the driver is subsequently unbound or removed,
> rapl_package_remove_pmu_locked() sees has_pmu == true and
> unconditionally calls perf_pmu_unregister(&rapl_pmu.pmu) on the
> zeroed-out structure. This attempts a list_del_rcu() on a NULL
> list head, immediately causing a kernel panic.
> 
> Fix this by checking if the PMU is actually registered before
> attempting to unregister it.
> 
> Signed-off-by: Sumeet Pawnikar <sumeet4linux@xxxxxxxxx>

Looks OK to me, so:

Reviewed-by: Abel Vesa <abel.vesa@xxxxxxxxxxxxxxxx>