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Commit c1528193 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Greg Kroah-Hartman
Browse files

bpf: Fix preempt_enable_no_resched() abuse 



[ 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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent aea54f61

include/linux/bpf.h

+1 −1
Original line number Diff line number Diff line
@@ -400,7 +400,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, 
		}					\

_out:							\

		rcu_read_unlock();			\

		preempt_enable_no_resched();		\

		preempt_enable();			\

		_ret;					\

	 })