On Wed, 3 Apr 2024 15:35:47 +0100 Mark Rutland <mark.rutland@xxxxxxx> wrote: > On Wed, Apr 03, 2024 at 08:51:07PM +0800, Dawei Li wrote: > > For CONFIG_CPUMASK_OFFSTACK=y kernel, explicit allocation of cpumask > > variable on stack is not recommended since it can cause potential stack > > overflow. > > > > Instead, kernel code should always use *cpumask_var API(s) to allocate > > cpumask var in config-neutral way, leaving allocation strategy to > > CONFIG_CPUMASK_OFFSTACK. > > > > But dynamic allocation in cpuhp's teardown callback is somewhat problematic > > for if allocation fails(which is unlikely but still possible): > > - If -ENOMEM is returned to caller, kernel crashes for non-bringup > > teardown; > > - If callback pretends nothing happened and returns 0 to caller, it may > > trap system into an in-consisitent/compromised state; > > > > Use newly-introduced cpumask_any_and_but() to address all issues above. > > It eliminates usage of temporary cpumask var in generic way, no matter how > > the cpumask var is allocated. > > > > Suggested-by: Mark Rutland <mark.rutland@xxxxxxx> > > Signed-off-by: Dawei Li <dawei.li@xxxxxxxxxxxx> > > The logic looks good to me, but I'd like the commit message updated the same as > per my comment on patch 2. > > With that commit message: > > Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx> Acked-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
