diff options
author | Hou Tao <houtao1@huawei.com> | 2023-10-20 16:31:57 +0300 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2023-10-21 00:15:06 +0300 |
commit | b460bc8302f222d346f0c15bba980eb8c36d6278 (patch) | |
tree | 73bd8effe56c8dcae3d9bfd166ff6772d5abb604 /mm | |
parent | 394e6869f0185e89cb815db29bf819474df858ae (diff) | |
download | linux-b460bc8302f222d346f0c15bba980eb8c36d6278.tar.xz |
mm/percpu.c: introduce pcpu_alloc_size()
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.
Acked-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231020133202.4043247-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/percpu.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index ea607078368d..60ed078e4cd0 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -2245,6 +2245,37 @@ static void pcpu_balance_workfn(struct work_struct *work) } /** + * pcpu_alloc_size - the size of the dynamic percpu area + * @ptr: pointer to the dynamic percpu area + * + * Returns the size of the @ptr allocation. This is undefined for statically + * defined percpu variables as there is no corresponding chunk->bound_map. + * + * RETURNS: + * The size of the dynamic percpu area. + * + * CONTEXT: + * Can be called from atomic context. + */ +size_t pcpu_alloc_size(void __percpu *ptr) +{ + struct pcpu_chunk *chunk; + unsigned long bit_off, end; + void *addr; + + if (!ptr) + return 0; + + addr = __pcpu_ptr_to_addr(ptr); + /* No pcpu_lock here: ptr has not been freed, so chunk is still alive */ + chunk = pcpu_chunk_addr_search(addr); + bit_off = (addr - chunk->base_addr) / PCPU_MIN_ALLOC_SIZE; + end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk), + bit_off + 1); + return (end - bit_off) * PCPU_MIN_ALLOC_SIZE; +} + +/** * free_percpu - free percpu area * @ptr: pointer to area to free * |