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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 <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
pull/1133/head
Hou Tao 2025-01-08 09:07:17 +08:00 committed by Alexei Starovoitov
parent 25dc65f75b
commit 9e6c958b54
1 changed files with 7 additions and 8 deletions
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15
kernel/bpf/bpf_task_storage.c
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@ -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)