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[73.219.103.14]) by smtp.gmail.com with ESMTPSA id n24-20020ac86758000000b0031ed8ef7982sm9715714qtp.22.2022.07.19.16.43.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Jul 2022 16:43:47 -0700 (PDT) Message-ID: <7462e934-f746-eef7-ff92-0eeb8cc08b82@gmail.com> Date: Tue, 19 Jul 2022 19:43:46 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v4 00/34] Printbufs - new data structure for building strings Content-Language: en-US To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, pmladek@suse.com, enozhatsky@chromium.org, linux@rasmusvillemoes.dk, willy@infradead.org References: <20220620004233.3805-1-kent.overstreet@gmail.com> <20220719191522.4002a5fb@gandalf.local.home> From: Kent Overstreet In-Reply-To: <20220719191522.4002a5fb@gandalf.local.home> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/19/22 19:15, Steven Rostedt wrote: > On Sun, 19 Jun 2022 20:41:59 -0400 > Kent Overstreet wrote: > >> Core idea: Wouldn't it be nice if we had a common data structure and calling >> convention for outputting strings? > > Because seq_buf gives us this already, the cover letter really just needs > to state exactly what the benefit is to replace seq_buf with printbuf (and > why seq_buf can not be simply extended to do some extra features). - seq_buf has the wrong semantics on overflow for what vsnprintf needs. - seq_buf is somewhat unnecessarily coupled to tracing needs - the readpos member has nothing to do with outputting formatting strings, and some of the pretty-printers are tracing specific and don't really belong in a generic pretty-printing library. And, when I tried to talk to you about changing seq_buf to be more suitable you didn't respond - you just dropped off the IRC discussion we were having. > > I just applied your series and ran the tracing selftests and several of > them failed. > > # cd tools/testing/selftests/ftrace/ > # ./ftracetest Thank you for telling me where to find the tests. It would've saved us some back and forth (and I could've gotten on this sooner) if you'd responded when I asked before. It may seem like the perfectly natural place to look to you - who works on the code - but to someone who works on a variety of subsystems, each of which puts their test code (if they have any!) in a different place, it wasn't. However, when I enabled all the tracing kernel config options, your tests are now failing to run at all with: db_root: cannot open: /etc/target So now I've got to debug your tests, too. Gah.