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Tue, 02 Jul 2024 09:11:04 -0700 (PDT) Received: from krava ([176.105.156.1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4256b09a2bcsm202179825e9.36.2024.07.02.09.11.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jul 2024 09:11:04 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Tue, 2 Jul 2024 18:10:58 +0200 To: Peter Zijlstra Cc: Oleg Nesterov , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Steven Rostedt , Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCHv2 bpf-next 1/9] uprobe: Add support for session consumer Message-ID: References: <20240701164115.723677-1-jolsa@kernel.org> <20240701164115.723677-2-jolsa@kernel.org> <20240702130408.GH11386@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240702130408.GH11386@noisy.programming.kicks-ass.net> On Tue, Jul 02, 2024 at 03:04:08PM +0200, Peter Zijlstra wrote: > On Mon, Jul 01, 2024 at 06:41:07PM +0200, Jiri Olsa wrote: > > > +static void > > +uprobe_consumer_account(struct uprobe *uprobe, struct uprobe_consumer *uc) > > +{ > > + static unsigned int session_id; > > + > > + if (uc->session) { > > + uprobe->sessions_cnt++; > > + uc->session_id = ++session_id ?: ++session_id; > > + } > > +} > > The way I understand this code, you create a consumer every time you do > uprobe_register() and unregister makes it go away. > > Now, register one, then 4g-1 times register+unregister, then register > again. > > The above seems to then result in two consumers with the same > session_id, which leads to trouble. > > Hmm? ugh true.. will make it u64 :) I think we could store uprobe_consumer pointer+ref in session_consumer, and that would make the unregister path more interesting.. will check thanks, jirka