Hi, On 10/20/2023 12:16 PM, Alexei Starovoitov wrote: > 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. I will post v3 to update the API document. > > Thanks for the quick review! > > .
