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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: davem@davemloft.net
Cc: daniel@iogearbox.net, bpf@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH v4 bpf-next 2/9] bpf: Run sleepable programs with migration disabled
Date: Tue,  9 Feb 2021 19:36:27 -0800	[thread overview]
Message-ID: <20210210033634.62081-3-alexei.starovoitov@gmail.com> (raw)
In-Reply-To: <20210210033634.62081-1-alexei.starovoitov@gmail.com>

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 --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();
 }
 
-- 
2.24.1


  parent reply	other threads:[~2021-02-10  3:37 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-10  3:36 [PATCH v4 bpf-next 0/9] bpf: Misc improvements Alexei Starovoitov
2021-02-10  3:36 ` [PATCH v4 bpf-next 1/9] bpf: Optimize program stats Alexei Starovoitov
2021-02-12  3:26   ` Ilya Leoshkevich
2021-02-12  3:43     ` Alexei Starovoitov
2021-02-12  3:51       ` Ilya Leoshkevich
2021-02-10  3:36 ` Alexei Starovoitov [this message]
2021-02-10  3:36 ` [PATCH v4 bpf-next 3/9] bpf: Compute program stats for sleepable programs Alexei Starovoitov
2021-02-10  3:36 ` [PATCH v4 bpf-next 4/9] bpf: Add per-program recursion prevention mechanism Alexei Starovoitov
2021-02-10  3:36 ` [PATCH v4 bpf-next 5/9] selftest/bpf: Add a recursion test Alexei Starovoitov
2021-02-10  3:36 ` [PATCH v4 bpf-next 6/9] bpf: Count the number of times recursion was prevented Alexei Starovoitov
2021-02-10  3:36 ` [PATCH v4 bpf-next 7/9] selftests/bpf: Improve recursion selftest Alexei Starovoitov
2021-02-10  3:36 ` [PATCH v4 bpf-next 8/9] bpf: Allows per-cpu maps and map-in-map in sleepable programs Alexei Starovoitov
2021-02-10  3:36 ` [PATCH v4 bpf-next 9/9] selftests/bpf: Add a test for map-in-map and per-cpu maps in sleepable progs Alexei Starovoitov
2021-02-11 15:30 ` [PATCH v4 bpf-next 0/9] bpf: Misc improvements patchwork-bot+netdevbpf

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