diff options
| author |   Thomas Gleixner <tglx@linutronix.de> | 2020-02-24 15:01:39 +0100 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2020-02-24 16:18:20 -0800 |
| commit | 8a37963c7ac9ecb7f86f8ebda020e3f8d6d7b8a0 (patch) | |
| tree | ee849da409619592dbcaf62bdda95f53bcfdbb99 /kernel | |
| parent | perf/bpf: Remove preempt disable around BPF invocation (diff) | |
| download | linux-dev-8a37963c7ac9ecb7f86f8ebda020e3f8d6d7b8a0.tar.xz linux-dev-8a37963c7ac9ecb7f86f8ebda020e3f8d6d7b8a0.zip | |
bpf: Remove recursion prevention from rcu free callback
If an element is freed via RCU then recursion into BPF instrumentation
functions is not a concern. The element is already detached from the map
and the RCU callback does not hold any locks on which a kprobe, perf event
or tracepoint attached BPF program could deadlock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200224145643.259118710@linutronix.de
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/hashtab.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 65711a220fe0..431cef22d29d 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -706,15 +706,7 @@ static void htab_elem_free_rcu(struct rcu_head *head) struct htab_elem *l = container_of(head, struct htab_elem, rcu); struct bpf_htab *htab = l->htab; - /* must increment bpf_prog_active to avoid kprobe+bpf triggering while - * we're calling kfree, otherwise deadlock is possible if kprobes - * are placed somewhere inside of slub - */ - preempt_disable(); - __this_cpu_inc(bpf_prog_active); htab_elem_free(htab, l); - __this_cpu_dec(bpf_prog_active); - preempt_enable(); } static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l) |