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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3c70e4b9f8dsm23595649f8f.9.2025.08.27.12.33.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Aug 2025 12:33:09 -0700 (PDT) Date: Wed, 27 Aug 2025 20:32:40 +0100 From: David Laight To: Peter Zijlstra Cc: jolsa@kernel.org, oleg@redhat.com, andrii@kernel.org, mhiramat@kernel.org, linux-kernel@vger.kernel.org, alx@kernel.org, eyal.birger@gmail.com, kees@kernel.org, bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, haoluo@google.com, rostedt@goodmis.org, alan.maguire@oracle.com, David.Laight@aculab.com, thomas@t-8ch.de, mingo@kernel.org, rick.p.edgecombe@intel.com Subject: Re: [PATCH 2/6] uprobes/x86: Optimize is_optimize() Message-ID: <20250827203240.664a030c@pumpkin> In-Reply-To: <20250826081840.GD3245006@noisy.programming.kicks-ass.net> References: <20250821122822.671515652@infradead.org> <20250821123656.823296198@infradead.org> <20250826065158.1b7ad5fc@pumpkin> <20250826081840.GD3245006@noisy.programming.kicks-ass.net> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) 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-Transfer-Encoding: 7bit On Tue, 26 Aug 2025 10:18:40 +0200 Peter Zijlstra wrote: > On Tue, Aug 26, 2025 at 06:51:58AM +0100, David Laight wrote: > > > > @@ -1069,17 +1068,14 @@ int set_swbp(struct arch_uprobe *auprobe > > > unsigned long vaddr) > > > { > > > if (should_optimize(auprobe)) { > > > - bool optimized = false; > > > - int err; > > > - > > > /* > > > * We could race with another thread that already optimized the probe, > > > * so let's not overwrite it with int3 again in this case. > > > */ > > > - err = is_optimized(vma->vm_mm, vaddr, &optimized); > > > - if (err) > > > - return err; > > > - if (optimized) > > > + int ret = is_optimized(vma->vm_mm, vaddr); > > > + if (ret < 0) > > > + return ret; > > > + if (ret) > > > return 0; > > > > Looks like you should swap over 0 and 1. > > That would then be: if (ret <= 0) return ret; > > I considered that, but that was actually more confusing. Yes the return > check is neat, but urgh. > > The tri-state return is: > > <0 -- error > 0 -- false > 1 -- true > > and that is converted to the 'normal' convention: > > <0 -- error > 0 -- success > > > Making that intermediate: > > <0 -- error > 0 -- true > 1 -- false > > is just asking for trouble later. I'm sure the function name could be changed to make it all work :-) David