bpf: Fix preempt_enable_no_resched() abuse

Unless the very next line is schedule(), or implies it, one must not use
preempt_enable_no_resched(). It can cause a preemption to go missing and
thereby cause arbitrary delays, breaking the PREEMPT=y invariant.

Cc: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index f02367faa58dbe44171454de6af50777ddc0ebf3..944ccc310201d461e73d738fe8e971aaf9e1b454 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -510,7 +510,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
                }                                       \
 _out:                                                  \
                rcu_read_unlock();                      \
-               preempt_enable_no_resched();            \
+               preempt_enable();                       \
                _ret;                                   \
         })