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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49fbd1ce79csm82621135e9.0.2026.09.17.05.29.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 05:29:39 -0700 (PDT) Date: Thu, 17 Sep 2026 13:29:37 +0100 From: David Laight To: Christian Brauner Cc: linux-fsdevel@vger.kernel.org, Alexander Viro , Jan Kara , linuxppc-dev@lists.ozlabs.org, linux-gpio@vger.kernel.org, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-media@vger.kernel.org, wine-devel@list.winehq.org, linux-xfs@vger.kernel.org, io-uring@vger.kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] file: make struct fd_prepare const and kill its err field Message-ID: <20260917132937.5a15904e@pumpkin> In-Reply-To: <20260917-work-file-fd_prepare-v1-4-b87534ca49f3@kernel.org> References: <20260917-work-file-fd_prepare-v1-0-b87534ca49f3@kernel.org> <20260917-work-file-fd_prepare-v1-4-b87534ca49f3@kernel.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5B6EEC000B X-Stat-Signature: stdwicztm7y9cenppf56ai6i9wcjihwz X-HE-Tag: 1789648181-168695 X-HE-Meta: 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 VD3R19NS 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 17 Sep 2026 11:09:45 +0200 Christian Brauner wrote: > FD_PREPARE() releases the fd as soon as the file expression fails. The > fd either holds the descriptor or the error. The separate field is > redundant. Make fd and file plain members and struct fd_prepare simpler. > > Callers of FD_PREPARE() get a const pointer to the guard. Simplify all > users as they can now easily access the trivial struct. > ... > @@ -191,35 +175,39 @@ static __always_inline struct fd_prepare __fd_prepare(int fd, struct file *file) > * was allocated. If fd_publish() was called the fd and file are > * published and cleanup becomes a nop. > * > - * @_fdf: name of struct fd_prepare variable to define > + * @_fdf: name of the const struct fd_prepare pointer to define > * @_fd_flags: flags for get_unused_fd_flags() > * @_file_owned: struct file to take ownership of (can be expression) > */ > -#define FD_PREPARE(_fdf, _fd_flags, _file_owned) \ > - struct fd_prepare _fdf __cleanup(__fd_prepare_cleanup) = ({ \ > +#define __FD_PREPARE(_guard, _fdf, _fd_flags, _file_owned) \ > + struct fd_prepare _guard __cleanup(__fd_prepare_cleanup) = ({ \ > int __fd = get_unused_fd_flags(_fd_flags); \ > __fd_prepare(__fd, __fd < 0 ? NULL : (_file_owned)); \ > - }) > + }); \ > + const struct fd_prepare *const _fdf = &_guard Since the struct is only written by its initialiser, can't it just be 'const' ? David