[PATCH 08/16] smp: optimize smp_call_function_many_cond() for more

Yury Norov
2022-07-18T19:29:28Z

smp_call_function_many_cond() is often passed with cpu_online_mask.
If it's the case, we can use cpumask_copy instead of cpumask_and, which
is faster.

Caught with CONFIG_DEBUG_BITMAP:
[ 7.830337] Call trace:
[ 7.830397] __bitmap_check_params+0x1d8/0x260
[ 7.830499] smp_call_function_many_cond+0x1e8/0x45c
[ 7.830607] kick_all_cpus_sync+0x44/0x80
[ 7.830698] bpf_int_jit_compile+0x34c/0x5cc
[ 7.830796] bpf_prog_select_runtime+0x118/0x190
[ 7.830900] bpf_prepare_filter+0x3dc/0x51c
[ 7.830995] __get_filter+0xd4/0x170
[ 7.831145] sk_attach_filter+0x18/0xb0
[ 7.831236] sock_setsockopt+0x5b0/0x1214
[ 7.831330] __sys_setsockopt+0x144/0x170
[ 7.831431] __arm64_sys_setsockopt+0x2c/0x40
[ 7.831541] invoke_syscall+0x48/0x114
[ 7.831634] el0_svc_common.constprop.0+0x44/0xfc
[ 7.831745] do_el0_svc+0x30/0xc0
[ 7.831825] el0_svc+0x2c/0x84
[ 7.831899] el0t_64_sync_handler+0xbc/0x140
[ 7.831999] el0t_64_sync+0x18c/0x190
[ 7.832086] ---[ end trace 0000000000000000 ]---
[ 7.832375] b1: ffff24d1ffd98a48
[ 7.832385] b2: ffffa65533a29a38
[ 7.832393] b3: ffffa65533a29a38
[ 7.832400] nbits: 256
[ 7.832407] start: 0
[ 7.832412] off: 0
[ 7.832418] smp: Bitmap: parameters check failed
[ 7.832432] smp: include/linux/bitmap.h [363]: bitmap_and

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
kernel/smp.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index 7ed2b9b12f74..f96fdf944b4a 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -942,7 +942,11 @@ static void smp_call_function_many_cond(const struct cpumask *mask,

if (run_remote) {
cfd = this_cpu_ptr(&cfd_data);
- cpumask_and(cfd->cpumask, mask, cpu_online_mask);
+ if (mask == cpu_online_mask)
+ cpumask_copy(cfd->cpumask, cpu_online_mask);
+ else
+ cpumask_and(cfd->cpumask, mask, cpu_online_mask);
+
__cpumask_clear_cpu(this_cpu, cfd->cpumask);

cpumask_clear(cfd->cpumask_ipi);
--
2.34.1