netdev - [PATCH bpf-next v7 1/4] bpf: Allow syscall bpf programs to call non-recur helpers

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Message-ID: <20250730185903.3574598-2-ameryhung@gmail.com>
Date: Wed, 30 Jul 2025 11:58:52 -0700
From: Amery Hung <ameryhung@...il.com>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org,
	alexei.starovoitov@...il.com,
	andrii@...nel.org,
	daniel@...earbox.net,
	tj@...nel.org,
	memxor@...il.com,
	martin.lau@...nel.org,
	linux-lists@...alapatis.com,
	ameryhung@...il.com,
	kernel-team@...a.com
Subject: [PATCH bpf-next v7 1/4] bpf: Allow syscall bpf programs to call non-recur helpers

Allow syscall programs to call non-recur helpers too since syscall bpf
programs runs in process context through bpf syscall, BPF_PROG_TEST_RUN,
and cannot run recursively.

bpf_task_storage_{get,set} have "_recur" versions that call trylock
instead of taking the lock directly to avoid deadlock when called by
bpf programs that run recursively. Currently, only bpf_lsm, bpf_iter,
struct_ops without private stack are allow to call the non-recur helpers
since they cannot be recursively called in another bpf program.

Signed-off-by: Amery Hung <ameryhung@...il.com>
---
 include/linux/bpf_verifier.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 94defa405c85..c823f8efe3ed 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -962,6 +962,7 @@ static inline bool bpf_prog_check_recur(const struct bpf_prog *prog)
 	case BPF_PROG_TYPE_STRUCT_OPS:
 		return prog->aux->jits_use_priv_stack;
 	case BPF_PROG_TYPE_LSM:
+	case BPF_PROG_TYPE_SYSCALL:
 		return false;
 	default:
 		return true;
-- 
2.47.3