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Wed, 2 Apr 2025 13:40:23 -0500 Message-ID: <145ddb99-025b-4ed0-bee6-e1e2c70ff0bf@amd.com> Date: Thu, 3 Apr 2025 00:10:16 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 06/12] sched/wait: Add a waitqueue helper for fully exclusive priority waiters To: Sean Christopherson CC: , Paolo Bonzini , Albert Ou , Palmer Dabbelt , Paul Walmsley , Oliver Upton , Marc Zyngier , Juri Lelli , Peter Zijlstra , Ingo Molnar , , , , , David Matlack , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Vincent Guittot References: <20250401204425.904001-1-seanjc@google.com> <20250401204425.904001-7-seanjc@google.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250401204425.904001-7-seanjc@google.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF00000142:EE_|DM3PR12MB9436:EE_ X-MS-Office365-Filtering-Correlation-Id: 68190e15-3f13-4718-c0c6-08dd7215d777 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700013|376014|7416014|82310400026; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Apr 2025 18:40:29.0526 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 68190e15-3f13-4718-c0c6-08dd7215d777 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CH2PEPF00000142.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM3PR12MB9436 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250402_114034_135179_FB04A903 X-CRM114-Status: GOOD ( 14.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hello Sean, On 4/2/2025 2:14 AM, Sean Christopherson wrote: [..snip..] > diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c > index 51e38f5f4701..80d90d1dc24d 100644 > --- a/kernel/sched/wait.c > +++ b/kernel/sched/wait.c > @@ -47,6 +47,26 @@ void add_wait_queue_priority(struct wait_queue_head *wq_head, struct wait_queue_ > } > EXPORT_SYMBOL_GPL(add_wait_queue_priority); > > +int add_wait_queue_priority_exclusive(struct wait_queue_head *wq_head, > + struct wait_queue_entry *wq_entry) > +{ > + struct list_head *head = &wq_head->head; > + unsigned long flags; > + int r = 0; > + > + wq_entry->flags |= WQ_FLAG_EXCLUSIVE | WQ_FLAG_PRIORITY; > + spin_lock_irqsave(&wq_head->lock, flags); nit. Using "guard(spinlock_irqsave)(&wq_head->lock)" can help you get rid of both "flags" and "r". > + if (!list_empty(head) && > + (list_first_entry(head, typeof(*wq_entry), entry)->flags & WQ_FLAG_PRIORITY)) > + r = -EBUSY; > + else > + list_add(&wq_entry->entry, head); > + spin_unlock_irqrestore(&wq_head->lock, flags); > + > + return r; > +} > +EXPORT_SYMBOL(add_wait_queue_priority_exclusive); > + > void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry) > { > unsigned long flags; -- Thanks and Regards, Prateek