linux-kernel - [PATCH bpf-next v2 4/7] bpf: use rcu_read_lock_dont_migrate() for bpf_iter_run

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Message-ID: <20250819093424.1011645-5-dongml2@chinatelecom.cn>
Date: Tue, 19 Aug 2025 17:34:21 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: ast@...nel.org,
	paulmck@...nel.org
Cc: frederic@...nel.org,
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Subject: [PATCH bpf-next v2 4/7] bpf: use rcu_read_lock_dont_migrate() for bpf_iter_run_prog()

Use rcu_read_lock_dont_migrate() and rcu_read_unlock_migrate() in
bpf_iter_run_prog to obtain better performance when PREEMPT_RCU is
not enabled.

Signed-off-by: Menglong Dong <dongml2@...natelecom.cn>
---
v2:
- use rcu_read_lock_dont_migrate() instead of rcu_migrate_disable()
---
 kernel/bpf/bpf_iter.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index 0cbcae727079..6ac35430c573 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -705,13 +705,11 @@ int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx)
 		migrate_enable();
 		rcu_read_unlock_trace();
 	} else {
-		rcu_read_lock();
-		migrate_disable();
+		rcu_read_lock_dont_migrate();
 		old_run_ctx = bpf_set_run_ctx(&run_ctx);
 		ret = bpf_prog_run(prog, ctx);
 		bpf_reset_run_ctx(old_run_ctx);
-		migrate_enable();
-		rcu_read_unlock();
+		rcu_read_unlock_migrate();
 	}
 
 	/* bpf program can only return 0 or 1:
-- 
2.50.1