From 68cbd415dd4b9c5b9df69f0f091879e56bf5907a Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 21 Jun 2024 11:15:58 +0200 Subject: task_work: s/task_work_cancel()/task_work_cancel_func()/ A proper task_work_cancel() API that actually cancels a callback and not *any* callback pointing to a given function is going to be needed for perf events event freeing. Do the appropriate rename to prepare for that. Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240621091601.18227-2-frederic@kernel.org --- include/linux/task_work.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/task_work.h') diff --git a/include/linux/task_work.h b/include/linux/task_work.h index 795ef5a68429..23ab01ae185e 100644 --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -30,7 +30,7 @@ int task_work_add(struct task_struct *task, struct callback_head *twork, 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); +struct callback_head *task_work_cancel_func(struct task_struct *, task_work_func_t); void task_work_run(void); static inline void exit_task_work(struct task_struct *task) -- cgit v1.2.3 From f409530e4db9dd11b88cb7703c97c8f326ff6566 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 21 Jun 2024 11:15:59 +0200 Subject: task_work: Introduce task_work_cancel() again Re-introduce task_work_cancel(), this time to cancel an actual callback and not *any* callback pointing to a given function. This is going to be needed for perf events event freeing. Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240621091601.18227-3-frederic@kernel.org --- include/linux/task_work.h | 1 + kernel/task_work.c | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+) (limited to 'include/linux/task_work.h') diff --git a/include/linux/task_work.h b/include/linux/task_work.h index 23ab01ae185e..26b8a47f41fc 100644 --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -31,6 +31,7 @@ int task_work_add(struct task_struct *task, struct callback_head *twork, 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_func(struct task_struct *, task_work_func_t); +bool task_work_cancel(struct task_struct *task, struct callback_head *cb); void task_work_run(void); static inline void exit_task_work(struct task_struct *task) diff --git a/kernel/task_work.c b/kernel/task_work.c index 54ac24059daa..2134ac8057a9 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -136,6 +136,30 @@ task_work_cancel_func(struct task_struct *task, task_work_func_t func) return task_work_cancel_match(task, task_work_func_match, func); } +static bool task_work_match(struct callback_head *cb, void *data) +{ + return cb == data; +} + +/** + * task_work_cancel - cancel a pending work added by task_work_add() + * @task: the task which should execute the work + * @cb: the callback to remove if queued + * + * Remove a callback from a task's queue if queued. + * + * RETURNS: + * True if the callback was queued and got cancelled, false otherwise. + */ +bool task_work_cancel(struct task_struct *task, struct callback_head *cb) +{ + struct callback_head *ret; + + ret = task_work_cancel_match(task, task_work_match, cb); + + return ret == cb; +} + /** * task_work_run - execute the works added by task_work_add() * -- cgit v1.2.3 From 466e4d801cd438a1ab2c8a2cce1bef6b65c31bbb Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 4 Jul 2024 19:03:36 +0200 Subject: task_work: Add TWA_NMI_CURRENT as an additional notify mode. Adding task_work from NMI context requires the following: - The kasan_record_aux_stack() is not NMU safe and must be avoided. - Using TWA_RESUME is NMI safe. If the NMI occurs while the CPU is in userland then it will continue in userland and not invoke the `work' callback. Add TWA_NMI_CURRENT as an additional notify mode. In this mode skip kasan and use irq_work in hardirq-mode to for needed interrupt. Set TIF_NOTIFY_RESUME within the irq_work callback due to k[ac]san instrumentation in test_and_set_bit() which does not look NMI safe in case of a report. Suggested-by: Peter Zijlstra Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20240704170424.1466941-3-bigeasy@linutronix.de --- include/linux/task_work.h | 1 + kernel/task_work.c | 24 +++++++++++++++++++++--- 2 files changed, 22 insertions(+), 3 deletions(-) (limited to 'include/linux/task_work.h') diff --git a/include/linux/task_work.h b/include/linux/task_work.h index 26b8a47f41fc..cf5e7e891a77 100644 --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -18,6 +18,7 @@ enum task_work_notify_mode { TWA_RESUME, TWA_SIGNAL, TWA_SIGNAL_NO_IPI, + TWA_NMI_CURRENT, }; static inline bool task_work_pending(struct task_struct *task) diff --git a/kernel/task_work.c b/kernel/task_work.c index 2134ac8057a9..5c2daa7ad3f9 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -1,10 +1,18 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include static struct callback_head work_exited; /* all we need is ->next == NULL */ +static void task_work_set_notify_irq(struct irq_work *entry) +{ + test_and_set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); +} +static DEFINE_PER_CPU(struct irq_work, irq_work_NMI_resume) = + IRQ_WORK_INIT_HARD(task_work_set_notify_irq); + /** * task_work_add - ask the @task to execute @work->func() * @task: the task which should run the callback @@ -12,7 +20,7 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */ * @notify: how to notify the targeted task * * Queue @work for task_work_run() below and notify the @task if @notify - * is @TWA_RESUME, @TWA_SIGNAL, or @TWA_SIGNAL_NO_IPI. + * is @TWA_RESUME, @TWA_SIGNAL, @TWA_SIGNAL_NO_IPI or @TWA_NMI_CURRENT. * * @TWA_SIGNAL works like signals, in that the it will interrupt the targeted * task and run the task_work, regardless of whether the task is currently @@ -24,6 +32,8 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */ * kernel anyway. * @TWA_RESUME work is run only when the task exits the kernel and returns to * user mode, or before entering guest mode. + * @TWA_NMI_CURRENT works like @TWA_RESUME, except it can only be used for the + * current @task and if the current context is NMI. * * Fails if the @task is exiting/exited and thus it can't process this @work. * Otherwise @work->func() will be called when the @task goes through one of @@ -44,8 +54,13 @@ int task_work_add(struct task_struct *task, struct callback_head *work, { struct callback_head *head; - /* record the work call stack in order to print it in KASAN reports */ - kasan_record_aux_stack(work); + if (notify == TWA_NMI_CURRENT) { + if (WARN_ON_ONCE(task != current)) + return -EINVAL; + } else { + /* record the work call stack in order to print it in KASAN reports */ + kasan_record_aux_stack(work); + } head = READ_ONCE(task->task_works); do { @@ -66,6 +81,9 @@ int task_work_add(struct task_struct *task, struct callback_head *work, case TWA_SIGNAL_NO_IPI: __set_notify_signal(task); break; + case TWA_NMI_CURRENT: + irq_work_queue(this_cpu_ptr(&irq_work_NMI_resume)); + break; default: WARN_ON_ONCE(1); break; -- cgit v1.2.3