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Mon, 23 Jun 2025 20:13:04 -0700 (PDT) Received: from localhost ([2a03:2880:30ff:8::]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae054209efbsm810017466b.178.2025.06.23.20.13.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Jun 2025 20:13:03 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Eduard Zingerman , Emil Tsalapatis , Barret Rhoden , Matt Bobrowski , kkd@meta.com, kernel-team@meta.com Subject: [PATCH bpf-next v3 08/12] bpf: Report rqspinlock deadlocks/timeout to BPF stderr Date: Mon, 23 Jun 2025 20:12:48 -0700 Message-ID: <20250624031252.2966759-9-memxor@gmail.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250624031252.2966759-1-memxor@gmail.com> References: <20250624031252.2966759-1-memxor@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2091; h=from:subject; bh=Gp9N5evBaVBCgG5QHktE/qX6HSsv2j9p68dUzNTksxM=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBoWhWeH5LnjFBUl/YTCa4zYeyhv8RqisWwVI8lyB0B 399gT+KJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCaFoVngAKCRBM4MiGSL8RygNEEA C4XPYN6aHCWsStMICUkhdp6EFh/spuP3jd/e/RNTvvn7lK4ToNfOwHvxqUwxfnQdMz15gwSLSLT5sI /AE++aTsyc1RtnKeCUxiJlsZLqBIzvUCBU8M704lpeWwZRZ0y1xeM0hlNsS3G0qOWyKVNuOmmgU/da iBj0oNa01VQy7xkO9eCdnmHTkOO7M2rBbXURHr62+5hoTBHSZbsASRMQ1+OZnPlBWSmN4vjLlrYLkY H2W18+hhg71EuLOVJ7Iu534RxmaVFEGgnAiNlNFWiP5sQ+5nX+/l3377miNm8lCGbHGakYA/TIw+G5 YTpNcFRYZJ6kNFopw5PD8NfJqVFfw50bMgrdCOsT2Jo69kj8pkYHwXOXdFLAPKVQWPJd4iNDOzzY6X mSqr/m0VOlv+Z857jCcRBHcgVvtxAjyuBBT3wAWzsGNz305eoMFBrV+D9BdA1PAPA8jlUFncWLaNgJ 2+EYsg9Df41LKlwxgxSzvWH0AbkZns6mTHQD6piqQ8O0+mK+Ewk4guxUl0bCtAc22PsAWTmZfd36F2 050xGl5pQJi24By7Ap0ughah0kX6mT1P1PmbaMkTNOzN6fV2Qn4v7x1NpGRRTdFWXxSkbMKqP6PYMO hVWoYJnNZPPljDjQA2RsqQ5aLZxEUieU5oTJwAYv45D4JH58d9Plne9LRJPg== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Content-Transfer-Encoding: 8bit Begin reporting rqspinlock deadlocks and timeout to BPF program's stderr. Signed-off-by: Kumar Kartikeya Dwivedi --- 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