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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?q?Gnc4cG6+BDoSbzNHZr14n12jbdtB?= =?utf-8?q?LGZ9zn6B4vsK+f90Z3W/Siz4wqlQMQNdNeVdtPD0fvxv62bUF2fMz3j34KRwptHu+?= =?utf-8?q?n6gZAdroC/MHkK4xUjF/OMeqrilbpVZjnIc48VanS0iNr9yOjpxfxWBmZV2XdMM1R?= =?utf-8?q?LwIWfKX2DGm3/aWUw5A/g8V1dv9qep9PPlMybZYZjx/XjNX/7SvAklTbE6VozHE5+?= =?utf-8?q?+MSal2lquOHd/fBBGaSbnCiBzhyZgjnT8tMbym09jLb/OKBhjh7ugjvqmZ5d37TXp?= =?utf-8?q?m6zkAcBdnDGrMke4nRSaU0EMSTGSASfqdE0TJxpDTmJiv9jIkecQ7HCcFOuY7b2zQ?= =?utf-8?q?xOAAJrk9U50cYZDVIXl85towtFAQdncyAlsPM+8q9ShMiyOoYA0DJhjPbLzNnATR9?= =?utf-8?q?Td7oywRKtEixCP18O7+AUW5+nIGCIaDPMh/kczxzUytW5uXxMAvH7+MMF2KQy9O6A?= =?utf-8?q?ZjvhADhXOCO1lF7TYwSNNzVT6tHLOM3FLnRbLPE3zwAi23dqvKZAfQRF9tN7J7yn3?= =?utf-8?q?AQlWYkqM3i2ZnsJ8Z55m34+yyZovS3hOZCEjesKrQLpfijO20p6l8j0eDflqC+qGf?= =?utf-8?q?fdcCIz508KEx79Dpw2yzZ40tIGmtmxKRkeL8nk4hLARgPD6VGXIG/OD1VC7vAalZe?= =?utf-8?q?GBp35kG/LiMZcgMBCB0+wdam2CWzF1S1W/AXmtO0HSFVkvifdY/0tDtBd1Yz6yzY+?= =?utf-8?q?PLSaOkx5mDEAr7+nuIz/knish1WW2j9vlhaWS4kfU9J6peJX2GjZmiamZI4SUzkKQ?= =?utf-8?q?6wFwwZdLDSRveYPUFYr1KjNAE0oi6yiMKd8fr+16QvqVfm8Ic8MSh0I8tWdH/Akp6?= =?utf-8?q?A+rHAFPUwQKzhK1+XLAQnse87c8CHSnaT0yanGp5Ijf/5bERbYMFl43Bh/T31hTVV?= =?utf-8?q?e59a/r8UfLrjzRIAdfCyWVprZ6aElwOgJYqAOI73uagqrIkeifp2VcDCk+gWYZQZi?= =?utf-8?q?uaOwWAaJlAYz1mAWmq/PIRsMb4NLvTnNyOYZDenTSnBUlEpzJTH9Tdm4n8NGuHTwG?= =?utf-8?q?hEAflE1sLw69Loo7MC191TTKEiAJqydPEJJdzHC8u47VQhuE0cvo+fs+rE8JyaaMD?= =?utf-8?q?8vjf8E9xG7FXSy5hDRTIPbeaTAZn0pKlMgURNJsA+YgfjxuM3GBMrzkFqwotJu73z?= =?utf-8?q?eg9cTFeB6FRygPUkagTQqUHFy+N6buq3pYqYpBf9dVFc+reUHkqHis1ozbmBTDI3P?= =?utf-8?q?VlDIuIaXiFSkNxbhPPi7e8l/ubFKGWuMwRIMs8D252wv+M5nHPYaSC3/MnVDwHtOP?= =?utf-8?q?1jjuTrFh7wP2iPu3l/uYxyIY74dILIMPYx0LTvK7JCC6bN3eLHK1tHNhMEEJ+2Py+?= =?utf-8?q?Lh+Ui0iZunzGSyaYUcWu9eC5aFm2B/17hZjS4b0SdJ04ll2C4bTGFerrnbHhhbJLl?= =?utf-8?q?XfukpxmHBYdMq0V/d4QzZlTwfQRBZH5IwuyNIRafuW60XNqKJrKeV5TgUxXIW4Bei?= =?utf-8?q?q4N+A5dfSPFuNzJLfGoUIxfUHE8DWWZ3kb4YkEJ0/wamFSHDv1fSdYWxx+ZzX9Mis?= =?utf-8?q?2agh6ZGzlEoQg2hysRW5fc0YBT1/1UXFP5R7Kt2X9CRvJ4lXrljYTAI=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: e6df0cf1-0558-4ad5-c11e-08d9f06747b2 X-MS-Exchange-CrossTenant-AuthSource: DS7PR03MB5608.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Feb 2022 09:41:02.5768 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335836de-42ef-43a2-b145-348c2ee9ca5b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: kCKdK+D90pCOBMmZnvgHT6V/weArGTHIOG0KD7oHIhg0kJWihL4xgMkJ7EUfyrK9oH4dpRhnBc2VLQXi7PS/vg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR03MB3053 X-OriginatorOrg: citrix.com There's no need to subtract _QR_BIAS from the lock value for storing in the local cnts variable in the read lock slow path: the users of the value in cnts only care about the writer-related bits and use a mask to get the value. Note that further setting of cnts in rspin_until_writer_unlock already do not subtract _QR_BIAS. Signed-off-by: Roger Pau Monné Reviewed-by: Jan Beulich Reviewed-by: Luca Fancellu --- xen/common/rwlock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/xen/common/rwlock.c b/xen/common/rwlock.c index dadab372b5..aa15529bbe 100644 --- a/xen/common/rwlock.c +++ b/xen/common/rwlock.c @@ -47,7 +47,7 @@ void queue_read_lock_slowpath(rwlock_t *lock) while ( atomic_read(&lock->cnts) & _QW_WMASK ) cpu_relax(); - cnts = atomic_add_return(_QR_BIAS, &lock->cnts) - _QR_BIAS; + cnts = atomic_add_return(_QR_BIAS, &lock->cnts); rspin_until_writer_unlock(lock, cnts); /*