From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
To: bpf@vger.kernel.org
Cc: Emil Tsalapatis <emil@etsalapatis.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Barret Rhoden <brho@google.com>,
Matt Bobrowski <mattbobrowski@google.com>,
kkd@meta.com, kernel-team@meta.com
Subject: [PATCH bpf-next v5 08/12] bpf: Report rqspinlock deadlocks/timeout to BPF stderr
Date: Thu, 3 Jul 2025 13:48:14 -0700 [thread overview]
Message-ID: <20250703204818.925464-9-memxor@gmail.com> (raw)
In-Reply-To: <20250703204818.925464-1-memxor@gmail.com>
Begin reporting rqspinlock deadlocks and timeout to BPF program's
stderr.
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/rqspinlock.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/kernel/bpf/rqspinlock.c b/kernel/bpf/rqspinlock.c
index 338305c8852c..5ab354d55d82 100644
--- a/kernel/bpf/rqspinlock.c
+++ b/kernel/bpf/rqspinlock.c
@@ -666,6 +666,27 @@ EXPORT_SYMBOL_GPL(resilient_queued_spin_lock_slowpath);
__bpf_kfunc_start_defs();
+static void bpf_prog_report_rqspinlock_violation(const char *str, void *lock, bool irqsave)
+{
+ struct rqspinlock_held *rqh = this_cpu_ptr(&rqspinlock_held_locks);
+ struct bpf_stream_stage ss;
+ struct bpf_prog *prog;
+
+ prog = bpf_prog_find_from_stack();
+ if (!prog)
+ return;
+ bpf_stream_stage(ss, prog, BPF_STDERR, ({
+ bpf_stream_printk(ss, "ERROR: %s for bpf_res_spin_lock%s\n", str, irqsave ? "_irqsave" : "");
+ bpf_stream_printk(ss, "Attempted lock = 0x%px\n", lock);
+ bpf_stream_printk(ss, "Total held locks = %d\n", rqh->cnt);
+ for (int i = 0; i < min(RES_NR_HELD, rqh->cnt); i++)
+ bpf_stream_printk(ss, "Held lock[%2d] = 0x%px\n", i, rqh->locks[i]);
+ bpf_stream_dump_stack(ss);
+ }));
+}
+
+#define REPORT_STR(ret) ({ (ret) == -ETIMEDOUT ? "Timeout detected" : "AA or ABBA deadlock detected"; })
+
__bpf_kfunc int bpf_res_spin_lock(struct bpf_res_spin_lock *lock)
{
int ret;
@@ -676,6 +697,7 @@ __bpf_kfunc int bpf_res_spin_lock(struct bpf_res_spin_lock *lock)
preempt_disable();
ret = res_spin_lock((rqspinlock_t *)lock);
if (unlikely(ret)) {
+ bpf_prog_report_rqspinlock_violation(REPORT_STR(ret), lock, false);
preempt_enable();
return ret;
}
@@ -698,6 +720,7 @@ __bpf_kfunc int bpf_res_spin_lock_irqsave(struct bpf_res_spin_lock *lock, unsign
local_irq_save(flags);
ret = res_spin_lock((rqspinlock_t *)lock);
if (unlikely(ret)) {
+ bpf_prog_report_rqspinlock_violation(REPORT_STR(ret), lock, true);
local_irq_restore(flags);
preempt_enable();
return ret;
--
2.47.1
next prev parent reply other threads:[~2025-07-03 20:48 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-03 20:48 [PATCH bpf-next v5 00/12] BPF Standard Streams Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 01/12] bpf: Refactor bprintf buffer support Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 02/12] bpf: Introduce BPF standard streams Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 03/12] bpf: Add function to extract program source info Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 04/12] bpf: Ensure RCU lock is held around bpf_prog_ksym_find Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 05/12] bpf: Add function to find program from stack trace Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 06/12] bpf: Add dump_stack() analogue to print to BPF stderr Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 07/12] bpf: Report may_goto timeout " Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` Kumar Kartikeya Dwivedi [this message]
2025-07-30 23:02 ` [PATCH bpf-next v5 08/12] bpf: Report rqspinlock deadlocks/timeout " Kees Cook
2025-07-30 23:07 ` Alexei Starovoitov
2025-07-30 23:09 ` Kees Cook
2025-07-30 23:13 ` Alexei Starovoitov
2025-07-30 23:19 ` Kees Cook
2025-07-03 20:48 ` [PATCH bpf-next v5 09/12] libbpf: Add bpf_stream_printk() macro Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 10/12] libbpf: Introduce bpf_prog_stream_read() API Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 11/12] bpftool: Add support for dumping streams Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 12/12] selftests/bpf: Add tests for prog streams Kumar Kartikeya Dwivedi
2025-07-04 2:40 ` [PATCH bpf-next v5 00/12] BPF Standard Streams patchwork-bot+netdevbpf
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