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[141.239.158.86]) by smtp.gmail.com with ESMTPSA id y14-20020a62f24e000000b006e25d4085b4sm9897082pfl.27.2024.02.22.00.05.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Feb 2024 00:05:18 -0800 (PST) Sender: Tejun Heo Date: Wed, 21 Feb 2024 22:05:16 -1000 From: Tejun Heo To: Lai Jiangshan Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, allen.lkml@gmail.com, kernel-team@meta.com Subject: Re: [PATCH 1/7] workqueue: Preserve OFFQ bits in cancel[_sync] paths Message-ID: References: <20240221174333.700197-1-tj@kernel.org> <20240221174333.700197-2-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Feb 22, 2024 at 12:35:31PM +0800, Lai Jiangshan wrote: > Hello, > > On Thu, Feb 22, 2024 at 1:43 AM Tejun Heo wrote: > > > > > /* Convenience constants - of type 'unsigned long', not 'enum'! */ > > #define WORK_OFFQ_CANCELING (1ul << WORK_OFFQ_CANCELING_BIT) > > +#define WORK_OFFQ_FLAG_MASK (((1ul << WORK_OFFQ_FLAG_BITS) - 1) << WORK_OFFQ_FLAG_SHIFT) > > It can use GENMASK. So, that'd be GENMASK(WORK_OFFQ_FLAG_SHIFT + WORK_OFFQ_FLAG_BITS - 1, WORK_OFFQ_FLAG_SHIFT) I'm not quite sure that's an improvement. It's longer and more indirect - the open coded one says "BITS number of 1's shifted by SHIFT", which is shorter and easier to comprehend. Another thing is that none of the other masks fits GENMASK either. The only other candidate is WORK_STRUCT_PWQ_MASK but the number of bits in that mask depends on the size of ulong, so it can't use GENMASK. I don't think using GENMASK would be an improvement here. Thanks. -- tejun