Commit 0edd6b64 authored Apr 23, 2019 by Peter Zijlstra Committed by Alexei Starovoitov Apr 25, 2019

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>

parent 6dd7f140

include/linux/bpf.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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; \
		})

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