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Subject[PATCH AUTOSEL 5.0 23/34] bpf: Fix preempt_enable_no_resched() abuse
Date
From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit 0edd6b64d1939e9e9168ff27947995bb7751db5d ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/bpf.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e734f163bd0b9..1fbd7672e4b37 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -455,7 +455,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
} \
_out: \
rcu_read_unlock(); \
- preempt_enable_no_resched(); \
+ preempt_enable(); \
_ret; \
})

--
2.20.1
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