From 25dc65f75b08281a42823673d1751c82618ce7a3 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Wed, 8 Jan 2025 09:07:16 +0800 Subject: [PATCH] bpf: Remove migrate_{disable|enable} from bpf_cgrp_storage_lock helpers Three callers of bpf_cgrp_storage_lock() are ->map_lookup_elem, ->map_update_elem, ->map_delete_elem from bpf syscall. BPF syscall for these three operations of cgrp storage has already disabled migration. Two call sites of bpf_cgrp_storage_trylock() are bpf_cgrp_storage_get(), and bpf_cgrp_storage_delete() helpers. The running contexts of these helpers have already disabled migration. Therefore, it is safe to remove migrate_disable() for these callers. However, bpf_cgrp_storage_free() also invokes bpf_cgrp_storage_lock() and its running context doesn't disable migration. Therefore, also add the missed migrate_{disabled|enable} in bpf_cgrp_storage_free(). Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20250108010728.207536-5-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/bpf_cgrp_storage.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/kernel/bpf/bpf_cgrp_storage.c b/kernel/bpf/bpf_cgrp_storage.c index 20f05de92e9c..d5dc65bb1755 100644 --- a/kernel/bpf/bpf_cgrp_storage.c +++ b/kernel/bpf/bpf_cgrp_storage.c @@ -15,22 +15,20 @@ static DEFINE_PER_CPU(int, bpf_cgrp_storage_busy); static void bpf_cgrp_storage_lock(void) { - migrate_disable(); + cant_migrate(); this_cpu_inc(bpf_cgrp_storage_busy); } static void bpf_cgrp_storage_unlock(void) { this_cpu_dec(bpf_cgrp_storage_busy); - migrate_enable(); } static bool bpf_cgrp_storage_trylock(void) { - migrate_disable(); + cant_migrate(); if (unlikely(this_cpu_inc_return(bpf_cgrp_storage_busy) != 1)) { this_cpu_dec(bpf_cgrp_storage_busy); - migrate_enable(); return false; } return true; @@ -47,17 +45,18 @@ void bpf_cgrp_storage_free(struct cgroup *cgroup) { struct bpf_local_storage *local_storage; + migrate_disable(); rcu_read_lock(); local_storage = rcu_dereference(cgroup->bpf_cgrp_storage); - if (!local_storage) { - rcu_read_unlock(); - return; - } + if (!local_storage) + goto out; bpf_cgrp_storage_lock(); bpf_local_storage_destroy(local_storage); bpf_cgrp_storage_unlock(); +out: rcu_read_unlock(); + migrate_enable(); } static struct bpf_local_storage_data *