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Sat, 17 Oct 2026 16:25:48 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Sat, 17 Oct 2026 23:25:48 +0000 Message-Id: Cc: "Nam Cao" , "Wen Yang" , "Tobias Schaffner" , "Viktor Malik" Subject: Re: [PATCH v2 10/15] tools/rv: Add BPF monitors From: "Alexei Starovoitov" To: "John Ogness" , "Gabriele Monaco" , , , , "Steven Rostedt" In-Reply-To: <87v770uuyr.fsf@jogness.linutronix.de> References: <20261001152042.124445-1-gmonaco@redhat.com> <20261001152042.124445-11-gmonaco@redhat.com> <878q3xtptq.fsf@jogness.linutronix.de> <8B3FF026-6159-48CF-8FEA-AF2FACD2E4EB@redhat.com> <87bj8s8ih9.fsf@jogness.linutronix.de> <87v770uuyr.fsf@jogness.linutronix.de> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sat, Oct 17, 2026 at 07:02 PM John Ogness wrote: > It would be nice if it could be filtered so that only RV violation > bpf_printk's would trigger. I do not think it is possible for a filter > to do primitive pattern matching on @bpf_string. Or am I wrong? not an ftrace expert, but it should be possible. bpf_string is a dynamic string field and filters take globs on those. > With the "new" ringbuffer and nbcon implementations, it no longer dos-es > the kernel, so I have no problem with bpf programs calling > printk_deferred(). And besides, userspace can already blast the > ringbuffer and consoles via /dev/kmsg. well, /dev/kmsg is ratelimited unless printk.devkmsg=on, but the kfunc wouldn't be. I still feel that bpf_stream + user space that writes into /dev/kmsg is a better design.