From 1dfc9d60a69ec148e1cb709256617d86e5f0e8f8 Mon Sep 17 00:00:00 2001 From: Krzysztof Kozlowski Date: Thu, 5 Mar 2026 22:45:40 +0100 Subject: workqueue: devres: Add device-managed allocate workqueue Add a Resource-managed version of alloc_workqueue() to fix common problem of drivers mixing devm() calls with destroy_workqueue. Such naive and discouraged driver approach leads to difficult to debug bugs when the driver: 1. Allocates workqueue in standard way and destroys it in driver remove() callback, 2. Sets work struct with devm_work_autocancel(), 3. Registers interrupt handler with devm_request_threaded_irq(). Which leads to following unbind/removal path: 1. destroy_workqueue() via driver remove(), Any interrupt coming now would still execute the interrupt handler, which queues work on destroyed workqueue. 2. devm_irq_release(), 3. devm_work_drop() -> cancel_work_sync() on destroyed workqueue. devm_alloc_workqueue() has two benefits: 1. Solves above problem of mix-and-match devres and non-devres code in driver, 2. Simplify any sane drivers which were correctly using alloc_workqueue() + devm_add_action_or_reset(). Signed-off-by: Krzysztof Kozlowski Acked-by: Tejun Heo Reviewed-by: Andy Shevchenko Signed-off-by: Tejun Heo --- kernel/workqueue.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'kernel/workqueue.c') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index aeaec79bc09c..19d20f3039d9 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -41,6 +41,7 @@ #include #include #include +#include #include #include #include @@ -5891,6 +5892,33 @@ struct workqueue_struct *alloc_workqueue_noprof(const char *fmt, } EXPORT_SYMBOL_GPL(alloc_workqueue_noprof); +static void devm_workqueue_release(void *res) +{ + destroy_workqueue(res); +} + +__printf(2, 5) struct workqueue_struct * +devm_alloc_workqueue(struct device *dev, const char *fmt, unsigned int flags, + int max_active, ...) +{ + struct workqueue_struct *wq; + va_list args; + int ret; + + va_start(args, max_active); + wq = alloc_workqueue(fmt, flags, max_active, args); + va_end(args); + if (!wq) + return NULL; + + ret = devm_add_action_or_reset(dev, devm_workqueue_release, wq); + if (ret) + return NULL; + + return wq; +} +EXPORT_SYMBOL_GPL(devm_alloc_workqueue); + #ifdef CONFIG_LOCKDEP __printf(1, 5) struct workqueue_struct * -- cgit v1.2.3