On Thu, Oct 19, 2023 at 9:09 PM Dennis Zhou <dennis@xxxxxxxxxx> wrote: > > On Wed, Oct 18, 2023 at 07:33:38PM +0800, Hou Tao wrote: > > From: Hou Tao <houtao1@xxxxxxxxxx> > > > > Introduce pcpu_alloc_size() to get the size of the dynamic per-cpu > > area. It will be used by bpf memory allocator in the following patches. > > BPF memory allocator maintains per-cpu area caches for multiple area > > sizes and its free API only has the to-be-freed per-cpu pointer, so it > > needs the size of dynamic per-cpu area to select the corresponding cache > > when bpf program frees the dynamic per-cpu pointer. > > > > Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx> > > --- > > include/linux/percpu.h | 1 + > > mm/percpu.c | 30 ++++++++++++++++++++++++++++++ > > 2 files changed, 31 insertions(+) > > > > diff --git a/include/linux/percpu.h b/include/linux/percpu.h > > index 68fac2e7cbe6..8c677f185901 100644 > > --- a/include/linux/percpu.h > > +++ b/include/linux/percpu.h > > @@ -132,6 +132,7 @@ extern void __init setup_per_cpu_areas(void); > > extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp) __alloc_size(1); > > extern void __percpu *__alloc_percpu(size_t size, size_t align) __alloc_size(1); > > extern void free_percpu(void __percpu *__pdata); > > +extern size_t pcpu_alloc_size(void __percpu *__pdata); > > > > DEFINE_FREE(free_percpu, void __percpu *, free_percpu(_T)) > > > > diff --git a/mm/percpu.c b/mm/percpu.c > > index 76b9c5e63c56..b0cea2dc16a9 100644 > > --- a/mm/percpu.c > > +++ b/mm/percpu.c > > @@ -2244,6 +2244,36 @@ static void pcpu_balance_workfn(struct work_struct *work) > > mutex_unlock(&pcpu_alloc_mutex); > > } > > > > +/** > > + * pcpu_alloc_size - the size of the dynamic percpu area > > + * @ptr: pointer to the dynamic percpu area > > + * > > + * Return the size of the dynamic percpu area @ptr. > > + * > > Alexei, can you modify the above comment to: > > Returns the size of the @ptr allocation. This is undefined for statically > defined percpu variables as there is no corresponding chunk->bound_map. Good point! Will do. Thanks for the quick review!
