From 9e6c958b546692fcdd0da2c2c3b2ac1da6e0233f Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Wed, 8 Jan 2025 09:07:17 +0800 Subject: [PATCH] bpf: Remove migrate_{disable|enable} from bpf_task_storage_lock helpers Three callers of bpf_task_storage_lock() are ->map_lookup_elem, ->map_update_elem, ->map_delete_elem from bpf syscall. BPF syscall for these three operations of task storage has already disabled migration. Another two callers are bpf_task_storage_get() and bpf_task_storage_delete() helpers which will be used by BPF program. Two callers of bpf_task_storage_trylock() are bpf_task_storage_get() and bpf_task_storage_delete() helpers. The running contexts of these helpers have already disabled migration. Therefore, it is safe to remove migrate_{disable|enable} from task storage lock helpers for these call sites. However, bpf_task_storage_free() also invokes bpf_task_storage_lock() and its running context doesn't disable migration, therefore, add the missed migrate_{disable|enable} in bpf_task_storage_free(). Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20250108010728.207536-6-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/bpf_task_storage.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c index bf7fa15fdcc6..1109475953c0 100644 --- a/kernel/bpf/bpf_task_storage.c +++ b/kernel/bpf/bpf_task_storage.c @@ -24,22 +24,20 @@ static DEFINE_PER_CPU(int, bpf_task_storage_busy); static void bpf_task_storage_lock(void) { - migrate_disable(); + cant_migrate(); this_cpu_inc(bpf_task_storage_busy); } static void bpf_task_storage_unlock(void) { this_cpu_dec(bpf_task_storage_busy); - migrate_enable(); } static bool bpf_task_storage_trylock(void) { - migrate_disable(); + cant_migrate(); if (unlikely(this_cpu_inc_return(bpf_task_storage_busy) != 1)) { this_cpu_dec(bpf_task_storage_busy); - migrate_enable(); return false; } return true; @@ -72,18 +70,19 @@ void bpf_task_storage_free(struct task_struct *task) { struct bpf_local_storage *local_storage; + migrate_disable(); rcu_read_lock(); local_storage = rcu_dereference(task->bpf_storage); - if (!local_storage) { - rcu_read_unlock(); - return; - } + if (!local_storage) + goto out; bpf_task_storage_lock(); bpf_local_storage_destroy(local_storage); bpf_task_storage_unlock(); +out: rcu_read_unlock(); + migrate_enable(); } static void *bpf_pid_task_storage_lookup_elem(struct bpf_map *map, void *key)