From: Hou Tao <houtao1@xxxxxxxxxx>
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 <houtao1@xxxxxxxxxx>
---
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 *
--
2.29.2
