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b=UI587/8wFhC93yPuyUl8XlOAf8zdtin2ESz8bMGE07mY7fXpa622BfSDevvCCcMvzqs4hMCiUQx97EdJj+949JNDWpins2RicFxW6Gd2JSeYqAeP4B2p7YwwoJGu3EKbQUGMRauIxM1rY4MmRG19lH1LPrB+RUHE0JQVvnl7Gmw= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=prevas.dk; Received: from DB7PR10MB2475.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:10:41::17) by PAVPR10MB7091.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:102:317::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8489.28; Thu, 6 Mar 2025 09:48:46 +0000 Received: from DB7PR10MB2475.EURPRD10.PROD.OUTLOOK.COM ([fe80::7e2c:5309:f792:ded4]) by DB7PR10MB2475.EURPRD10.PROD.OUTLOOK.COM ([fe80::7e2c:5309:f792:ded4%5]) with mapi id 15.20.8511.017; Thu, 6 Mar 2025 09:48:46 +0000 From: Rasmus Villemoes To: Linus Torvalds Cc: Oleg Nesterov , Mateusz Guzik , K Prateek Nayak , "Sapkal, Swapnil" , Manfred Spraul , Christian Brauner , David Howells , WangYuli , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Shenoy, Gautham Ranjal" , Neeraj.Upadhyay@amd.com, Ananth.narayan@amd.com, Matthew Wilcox , Nick Desaulniers Subject: Re: [PATCH] pipe_read: don't wake up the writer if the pipe is still full In-Reply-To: (Linus Torvalds's message of "Wed, 5 Mar 2025 06:50:26 -1000") References: <20250228143049.GA17761@redhat.com> <20250228163347.GB17761@redhat.com> <03a1f4af-47e0-459d-b2bf-9f65536fc2ab@amd.com> <741fe214-d534-4484-9cf3-122aabe6281e@amd.com> <3jnnhipk2at3f7r23qb7fvznqg6dqw4rfrhajc7h6j2nu7twi2@wc3g5sdlfewt> <20250303202735.GD9870@redhat.com> <87h6475w9q.fsf@prevas.dk> Date: Thu, 06 Mar 2025 10:48:44 +0100 Message-ID: <874j065w1v.fsf@prevas.dk> User-Agent: Gnus/5.13 (Gnus v5.13) Content-Type: text/plain X-ClientProxiedBy: MM0P280CA0079.SWEP280.PROD.OUTLOOK.COM (2603:10a6:190:8::12) To DB7PR10MB2475.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:10:41::17) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DB7PR10MB2475:EE_|PAVPR10MB7091:EE_ X-MS-Office365-Filtering-Correlation-Id: c5f41413-9e45-4dde-4d71-08dd5c9416e5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|52116014|7416014|366016|1800799024|7053199007|38350700014; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?eHVeiPkHFtPzDbxIc9v/bfjQJADYR0HCOwQd9AUgWbo9i1F1ZW4CCL1nUzm/?= =?us-ascii?Q?D9MqaelmCDjsj1l+/y5hijBCPBaWhNoqD/gzRJn/lolHcGTDQ4UXiGV36kHw?= =?us-ascii?Q?stl/tqhsxHzSPtIFK9C3fucBsB7ZMQ75eGCl7SIjl5RZJIwXIeoqL5r9ZkD9?= =?us-ascii?Q?T6xhruunKc5wMv842cOYQh4lriXCANVZ+eLyTdUOj8/GEREp3I9GMAyVWPPj?= =?us-ascii?Q?x37Bg30c5GsY99wBHRqiu7ZpjFp2IfCAZMKrIZeFhCD+N4zGqJqPJBF/jrU9?= =?us-ascii?Q?g0UtiHgqLSkl8dRA7seRtJxP2lbXIT6/lDPO1dhILoQnuvdw9tRj141PohNd?= =?us-ascii?Q?KcFwFyBKJnL9gSUMbZaXx5Cnkt3hnkhgGhB67vedYkfyN4VfEMrG4tbpv+YM?= =?us-ascii?Q?mwMYY62Pe8m1y+OOe9nIJxKo9OC3/q5u9enX7UscJxX47g6No/+X4Cik/4ki?= =?us-ascii?Q?J8Du1bYAK3r91Za4NShHpQrMEhFiaN5eq7XV9YzkFK9sRz2C1uf/EDRV+PWw?= =?us-ascii?Q?JvSsUAOynQXnOIrMyZyFi/HJt2pAUExgBAgoE44w5Z85lPakSIAf9iyLQLc4?= =?us-ascii?Q?2/oy+Bs47nfW3lxC9on87isI7zrQ0/kP1j2zMBqZHpMBCoWkIBeDrme870in?= =?us-ascii?Q?i7xjtzdP7cczFRmBvMmM6Hiw77ZR0Ajzt/caB8prietAsnNdlKKGtY8av1lz?= =?us-ascii?Q?b+GKPLICKr/xpGLXVxNb2/hyP3MLkGQ824x7I4l1Uk8l+TuN0ScEKZpWY7Fm?= =?us-ascii?Q?atnjwirCUadPQIVTNOglYQtscLh+CUhjwmAReaaiK8wg8T4U7g8PaLbrn0S0?= =?us-ascii?Q?bmW0BrV7x3GmGfmMFsQ4GcDTUb5wzFw+9mY3SA+BNCDamEQ7C6Gz2NwVBEyM?= =?us-ascii?Q?LAPshwAbD73DFRf/D1n+bqDEPk7JICOdJ6UhCvd3RVDh1FyarFLNkjVXrqoU?= =?us-ascii?Q?LCK9GU2qofIUtG7FMPbEutpiTYSkewLmN2yEANI0Ik9fZLSo0wdQZ5V9G6aR?= =?us-ascii?Q?Kq6TAeDfAs9Geum5dhMd7ZymLSx07iHvZCMVkWCAwwqUn5h3KYYeRZVM6dgt?= =?us-ascii?Q?vKmyGI0xjedOlhqRke2gbxr56ZN6IJ1lgLuUJQFvTc5/NtXyCrFygMTDJMx9?= =?us-ascii?Q?8cuyGHlbYpNXHNJSDrRcYnUQvfzxxDp/ACESgQuAbrksk9CwVIeEFwLNoztl?= =?us-ascii?Q?NfjRCXGuyx1nq8zkr1Y6+9I1V92MxpBZR+CTQE+21o1v1+NRbNRmVswVprOF?= =?us-ascii?Q?BhHu9XOIisxwIWGLxPCRrD/dsEh548742FIXx8ve/qtJbuZHwDwfgP6Bc9jv?= =?us-ascii?Q?CLv/ry/dEhCwPj/xfLBY9yyzc8bU4YU9qHXMNGVH6yzop/IeK23JuE4BGJzO?= =?us-ascii?Q?tK+vyu7BH0NqTg4dVxPBLyFfRQ6HT5e5lUrdyU2UiydPyTX4iAD4fZv1raXO?= =?us-ascii?Q?kXGWbT7QcNsszIDs4aH2gpSb6L3vRgjxp9LccIO/VcgRDDoK3XrvNbu6k7O+?= =?us-ascii?Q?sYgJRKQv+BSeZtSDqqQbu8FdSLVkACP0euAl5Ku3zZIrUkCr9wwmJwaJ7BfY?= =?us-ascii?Q?3X5uAsKzue0cBBas4FMnD4NnP1Dn4kCa3SRKKMGW52H34TZahbwegUiV2P5s?= =?us-ascii?Q?Sg=3D=3D?= X-OriginatorOrg: prevas.dk X-MS-Exchange-CrossTenant-Network-Message-Id: c5f41413-9e45-4dde-4d71-08dd5c9416e5 X-MS-Exchange-CrossTenant-AuthSource: DB7PR10MB2475.EURPRD10.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Mar 2025 09:48:46.8068 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: d350cf71-778d-4780-88f5-071a4cb1ed61 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: pcS0RoRQ8aA/yHFXoFQrp6oN0ntrmPhAD+6fm7PyV1+cCzoyiM74C0hMQO8UoEQaprQdYlHWUkYoNXbSZyF9BAXjXv28NMe5DlOiezt6M+E= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PAVPR10MB7091 On Wed, Mar 05 2025, Linus Torvalds wrote: > On Wed, 5 Mar 2025 at 05:31, Rasmus Villemoes wrote: >> >> On Mon, Mar 03 2025, Linus Torvalds wrote: >> >> > +/* >> > + * We have to declare this outside 'struct pipe_inode_info', >> > + * but then we can't use 'union pipe_index' for an anonymous >> > + * union, so we end up having to duplicate this declaration >> > + * below. Annoying. >> > + */ >> > +union pipe_index { >> > + unsigned long head_tail; >> > + struct { >> > + pipe_index_t head; >> > + pipe_index_t tail; >> > + }; >> > +}; >> > + >> >> -fms-extensions ? Willy wanted to add that for use in mm/ some years ago >> [*], and it has come up a few other times as well. >> >> [*] https://lore.kernel.org/lkml/20180419152817.GD25406@bombadil.infradead.org/ > > Oh, I was unaware of that extension, and yes, it would have been > lovely here, avoiding that duplicate union declaration. > > But it does require clang support - I see that clang has a > '-fms-extensions' as well, so it's presumably there. Yes, it seems they do have it, but for mysterious reasons saying -fms-extensions is not quite enough to convince clang that one does intend to use that MS extension, one also has to say -Wno-microsoft-anon-tag, or it complains warning: anonymous unions are a Microsoft extension [-Wmicrosoft-anon-tag] Also, the warning text is somewhat misleading; anon unions itself have certainly been a gcc extension since forever, and nowadays a C11 thing, and clang has a separate -Wpedantic warning for that when using -std=c99: warning: anonymous unions are a C11 extension [-Wc11-extensions] The -W flag name actually suggests an improvement to the warning "_tagged_ anonymous unions are a Microsoft extension", but I really wonder why -fms-extensions isn't sufficient to silence that in the first place. Also, the warning seems to be on by default; it's not some -Wextra or -Wpedantic thing. cc += Nick Rasmus