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[209.85.208.42]) by smtp.gmail.com with ESMTPSA id vo9-20020a170907a80900b00a3ce268c015sm457619ejc.48.2024.02.12.14.08.37 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Feb 2024 14:08:38 -0800 (PST) Received: by mail-ed1-f42.google.com with SMTP id 4fb4d7f45d1cf-561519f8698so4073699a12.0 for ; Mon, 12 Feb 2024 14:08:37 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCUZR7Tjmjo80Uc0HRUam+QtboP4nVvOXcIEnZw74ApZVszdH0fZ3alCzGM/Bgz+7+SjWDUoESyh+L7BHV1Kj531sDQ= X-Received: by 2002:aa7:cd66:0:b0:561:f173:6611 with SMTP id ca6-20020aa7cd66000000b00561f1736611mr60172edb.35.1707775717604; Mon, 12 Feb 2024 14:08:37 -0800 (PST) MIME-Version: 1.0 References: <20240212163101.19614-1-mathieu.desnoyers@efficios.com> <20240212163101.19614-6-mathieu.desnoyers@efficios.com> <65ca95d086dfd_d2d429470@dwillia2-xfh.jf.intel.com.notmuch> In-Reply-To: <65ca95d086dfd_d2d429470@dwillia2-xfh.jf.intel.com.notmuch> From: Linus Torvalds Date: Mon, 12 Feb 2024 14:08:20 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 5/8] virtio: Treat alloc_dax() -EOPNOTSUPP failure as non-fatal To: Dan Williams Cc: Mathieu Desnoyers , Arnd Bergmann , Dave Chinner , linux-kernel@vger.kernel.org, Andrew Morton , Vishal Verma , Dave Jiang , Matthew Wilcox , Russell King , linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, dm-devel@lists.linux.dev, nvdimm@lists.linux.dev, linux-s390@vger.kernel.org, Alasdair Kergon , Mike Snitzer , Mikulas Patocka Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: j8pxsox8nrcp8xugh59m99m1kbzkgfnj X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 27B8F120016 X-Rspam-User: X-HE-Tag: 1707775720-388295 X-HE-Meta: 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 GO6w+R6r 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 12 Feb 2024 at 14:04, Dan Williams wrote: > > This works because the internals of virtio_fs_cleanup_dax(), "kill_dax() > and put_dax()", know how to handle a NULL @dax_dev. It is still early > days with the "cleanup" helpers, but I wonder if anyone else cares that > the DEFINE_FREE() above does not check for NULL? Well, the main reason for DEFINE_FREE() to check for NULL is not correctness, but code generation. See the comment about kfree() in : * NOTE: the DEFINE_FREE()'s @free expression includes a NULL test even though * kfree() is fine to be called with a NULL value. This is on purpose. This way * the compiler sees the end of our alloc_obj() function as [...] with the full explanation there. Now, whether the code wants to actually use the cleanup() helpers for a single use-case is debatable. But yes, if it does, I suspect it should use !IS_ERR_OR_NULL(ptr). Linus