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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id u11-20020a05600c19cb00b003d9fb04f658sm4683254wmq.4.2023.01.26.02.41.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 Jan 2023 02:41:41 -0800 (PST) Message-ID: Date: Thu, 26 Jan 2023 11:41:40 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 To: David Howells Cc: Al Viro , Christoph Hellwig , Matthew Wilcox , Jens Axboe , Jan Kara , Jeff Layton , Jason Gunthorpe , Logan Gunthorpe , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , John Hubbard References: <20230125210657.2335748-1-dhowells@redhat.com> <20230125210657.2335748-2-dhowells@redhat.com> <2613249.1674726566@warthog.procyon.org.uk> <2638928.1674729230@warthog.procyon.org.uk> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] iov_iter: Use __bitwise with the extraction_flags In-Reply-To: <2638928.1674729230@warthog.procyon.org.uk> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: EE8731A0003 X-Rspamd-Server: rspam01 X-Stat-Signature: 84htee5y4dqccs4df3fk5j3w41swukx5 X-HE-Tag: 1674729704-309698 X-HE-Meta: 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 JW/Ru+6w mWK9m8Fa1GAh/HmPr0Fkri/IN0OhL7YajdXDBjRncfvFD3DF5aoJd6wBDM7H5b+6/Nj6I6dsYBS8sLXRhXyOOZmKCTQJysCpH/VvwX9vBaGhlAfPnB0wjQYx9+K+FCXuTfBuxNnILf/ldW1v0gBXBCKA0qhBomEXZ9LEprr9FQGCs+oM1t18kTjJPrd72g6927dHv9jhflPTlkxRI7M1l7yqvSEn97dEVTEUtg53DsouBYhhjIGtwecJeTIZL46p9Pgik805bMmTWHtBF0Guu9GhJMB+k3wZYLGjd03fNnLnK9gUvpmo+NpspwfFNCtkEnnIxIsoTvtqAwET+F4+oAHhieGCmObu+kw5mN3h0lkDRUEnDfEUaunvFj35wYj9+/Z6fEcS7tRih7NuswJg/0iDAD7rJGzouDR1GZ2IG3KCxcKQhS+tdnqGUR/8s6AMCvnDJ 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: On 26.01.23 11:33, David Howells wrote: > Interestingly, things like __be32 are __bitwise. I wonder if that actually > makes sense or if it was just convenient so stop people doing arithmetic on > them. I guess doing AND/OR/XOR on them isn't a problem provided both > arguments are appropriately byte-swapped. I recall that __be32 and friends were one of the early users of __bitwise in the kernel. And the reason IIRC was exactly that: detect when no proper conversion was performed using static code analysis (Sparse). While some operations might make sense, the abuse is much more likely. LGTM, thanks! -- Thanks, David / dhildenb