From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75E0A186E for ; Tue, 3 Jan 2023 08:16:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEFE8C433D2; Tue, 3 Jan 2023 08:16:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672733818; bh=be2TTvhY8EBxKrzyJOJ+UfrGaKMECh2VPW9ojLS79P0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CDcH5R9uuD7OIu2QjU7A7x3KxPoLa/MbuTo68efWvXfkfjLhPPyqHP4WfHQCBmJuJ 1GfdoEFq0Z6//IA1jopXYQgvc2qH+Z5u+hwwqCJUa2PMqHQlKpMPFHODckD+vthMum ZZ+8Db/m+cCaxnpzP354WZ3B3jyeCVuAeEc2+H38= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oleg Nesterov , Jens Axboe Subject: [PATCH 5.10 54/63] task_work: add helper for more targeted task_work canceling Date: Tue, 3 Jan 2023 09:14:24 +0100 Message-Id: <20230103081311.827558617@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230103081308.548338576@linuxfoundation.org> References: <20230103081308.548338576@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jens Axboe [ Upstream commit c7aab1a7c52b82d9afd7e03c398eb03dc2aa0507 ] The only exported helper we have right now is task_work_cancel(), which cancels any task_work from a given task where func matches the queued work item. This is a bit too coarse for some use cases. Add a task_work_cancel_match() that allows to more specifically target individual work items outside of purely the callback function used. task_work_cancel() can be trivially implemented on top of that, hence do so. Reviewed-by: Oleg Nesterov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- include/linux/task_work.h | 2 ++ kernel/task_work.c | 35 ++++++++++++++++++++++++++++------- 2 files changed, 30 insertions(+), 7 deletions(-) --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -22,6 +22,8 @@ enum task_work_notify_mode { int task_work_add(struct task_struct *task, struct callback_head *twork, enum task_work_notify_mode mode); +struct callback_head *task_work_cancel_match(struct task_struct *task, + bool (*match)(struct callback_head *, void *data), void *data); struct callback_head *task_work_cancel(struct task_struct *, task_work_func_t); void task_work_run(void); --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -59,18 +59,17 @@ int task_work_add(struct task_struct *ta } /** - * task_work_cancel - cancel a pending work added by task_work_add() + * task_work_cancel_match - cancel a pending work added by task_work_add() * @task: the task which should execute the work - * @func: identifies the work to remove - * - * Find the last queued pending work with ->func == @func and remove - * it from queue. + * @match: match function to call * * RETURNS: * The found work or NULL if not found. */ struct callback_head * -task_work_cancel(struct task_struct *task, task_work_func_t func) +task_work_cancel_match(struct task_struct *task, + bool (*match)(struct callback_head *, void *data), + void *data) { struct callback_head **pprev = &task->task_works; struct callback_head *work; @@ -86,7 +85,7 @@ task_work_cancel(struct task_struct *tas */ raw_spin_lock_irqsave(&task->pi_lock, flags); while ((work = READ_ONCE(*pprev))) { - if (work->func != func) + if (!match(work, data)) pprev = &work->next; else if (cmpxchg(pprev, work, work->next) == work) break; @@ -96,6 +95,28 @@ task_work_cancel(struct task_struct *tas return work; } +static bool task_work_func_match(struct callback_head *cb, void *data) +{ + return cb->func == data; +} + +/** + * task_work_cancel - cancel a pending work added by task_work_add() + * @task: the task which should execute the work + * @func: identifies the work to remove + * + * Find the last queued pending work with ->func == @func and remove + * it from queue. + * + * RETURNS: + * The found work or NULL if not found. + */ +struct callback_head * +task_work_cancel(struct task_struct *task, task_work_func_t func) +{ + return task_work_cancel_match(task, task_work_func_match, func); +} + /** * task_work_run - execute the works added by task_work_add() *