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[v4,bpf-next,2/9] bpf: Run sleepable programs with migration disabled

Message ID 20210210033634.62081-3-alexei.starovoitov@gmail.com (mailing list archive)
State Accepted
Commit 031d6e02ddbb8dea747c1abb697d556901f07dd4
Delegated to: BPF
Headers show
Series bpf: Misc improvements | expand

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netdev/tree_selection success Clearly marked for bpf-next
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netdev/cc_maintainers warning 8 maintainers not CCed: yhs@fb.com kafai@fb.com netdev@vger.kernel.org ast@kernel.org songliubraving@fb.com john.fastabend@gmail.com kpsingh@kernel.org andrii@kernel.org
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netdev/build_32bit success Errors and warnings before: 1 this patch: 1
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 13 lines checked
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Commit Message

Alexei Starovoitov Feb. 10, 2021, 3:36 a.m. UTC 
From: Alexei Starovoitov <ast@kernel.org>

In older non-RT kernels migrate_disable() was the same as preempt_disable().
Since commit 74d862b682f5 ("sched: Make migrate_disable/enable() independent of RT")
migrate_disable() is real and doesn't prevent sleeping.
Running sleepable programs with migration disabled allows to add support for
program stats and per-cpu maps later.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
---
 kernel/bpf/trampoline.c | 2 ++
 1 file changed, 2 insertions(+)
diff mbox series

Patch

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 5be3beeedd74..89fc849ba271 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -425,11 +425,13 @@  void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start)
 void notrace __bpf_prog_enter_sleepable(void)
 {
 	rcu_read_lock_trace();
+	migrate_disable();
 	might_fault();
 }
 
 void notrace __bpf_prog_exit_sleepable(void)
 {
+	migrate_enable();
 	rcu_read_unlock_trace();
 }