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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-23 20:06:38 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-23 20:06:38 +0300
commit4a22709e21c2b1bedf90f68c823daf65d8e6b491 (patch)
treeb480c70465c11cb6b4d9e4f47b8e1824df2d5eea /kernel
parent0a14d7649872be966d12bc6c3056bb37c27b94bd (diff)
parent91989c707884ecc7cd537281ab1a4b8fb7219da3 (diff)
downloadlinux-4a22709e21c2b1bedf90f68c823daf65d8e6b491.tar.xz
Merge tag 'arch-cleanup-2020-10-22' of git://git.kernel.dk/linux-block
Pull arch task_work cleanups from Jens Axboe: "Two cleanups that don't fit other categories: - Finally get the task_work_add() cleanup done properly, so we don't have random 0/1/false/true/TWA_SIGNAL confusing use cases. Updates all callers, and also fixes up the documentation for task_work_add(). - While working on some TIF related changes for 5.11, this TIF_NOTIFY_RESUME cleanup fell out of that. Remove some arch duplication for how that is handled" * tag 'arch-cleanup-2020-10-22' of git://git.kernel.dk/linux-block: task_work: cleanup notification modes tracehook: clear TIF_NOTIFY_RESUME in tracehook_notify_resume()
Diffstat (limited to 'kernel')
-rw-r--r--kernel/entry/common.c1
-rw-r--r--kernel/entry/kvm.c4
-rw-r--r--kernel/events/uprobes.c2
-rw-r--r--kernel/irq/manage.c2
-rw-r--r--kernel/sched/fair.c2
-rw-r--r--kernel/task_work.c30
6 files changed, 24 insertions, 17 deletions
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 0a1e20f8d4e8..2b8366693d5c 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -161,7 +161,6 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
arch_do_signal(regs);
if (ti_work & _TIF_NOTIFY_RESUME) {
- clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
rseq_handle_notify_resume(NULL, regs);
}
diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c
index eb1a8a4c867c..b6678a5e3cf6 100644
--- a/kernel/entry/kvm.c
+++ b/kernel/entry/kvm.c
@@ -16,10 +16,8 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work)
if (ti_work & _TIF_NEED_RESCHED)
schedule();
- if (ti_work & _TIF_NOTIFY_RESUME) {
- clear_thread_flag(TIF_NOTIFY_RESUME);
+ if (ti_work & _TIF_NOTIFY_RESUME)
tracehook_notify_resume(NULL);
- }
ret = arch_xfer_to_guest_mode_handle_work(vcpu, ti_work);
if (ret)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 0e18aaf23a7b..00b0358739ab 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1823,7 +1823,7 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags)
t->utask->dup_xol_addr = area->vaddr;
init_task_work(&t->utask->dup_xol_work, dup_xol_work);
- task_work_add(t, &t->utask->dup_xol_work, true);
+ task_work_add(t, &t->utask->dup_xol_work, TWA_RESUME);
}
/*
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5df903fccb60..c460e0496006 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1162,7 +1162,7 @@ static int irq_thread(void *data)
handler_fn = irq_thread_fn;
init_task_work(&on_exit_work, irq_thread_dtor);
- task_work_add(current, &on_exit_work, false);
+ task_work_add(current, &on_exit_work, TWA_NONE);
irq_thread_check_affinity(desc, action);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index aa4c6227cd6d..e17012be4d14 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2928,7 +2928,7 @@ static void task_tick_numa(struct rq *rq, struct task_struct *curr)
curr->node_stamp += period;
if (!time_before(jiffies, curr->mm->numa_next_scan))
- task_work_add(curr, work, true);
+ task_work_add(curr, work, TWA_RESUME);
}
}
diff --git a/kernel/task_work.c b/kernel/task_work.c
index 613b2d634af8..8d6e1217c451 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -9,23 +9,28 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */
* task_work_add - ask the @task to execute @work->func()
* @task: the task which should run the callback
* @work: the callback to run
- * @notify: send the notification if true
+ * @notify: how to notify the targeted task
*
- * Queue @work for task_work_run() below and notify the @task if @notify.
- * Fails if the @task is exiting/exited and thus it can't process this @work.
- * Otherwise @work->func() will be called when the @task returns from kernel
- * mode or exits.
+ * Queue @work for task_work_run() below and notify the @task if @notify
+ * is @TWA_RESUME or @TWA_SIGNAL. @TWA_SIGNAL works like signals, in that the
+ * it will interrupt the targeted task and run the task_work. @TWA_RESUME
+ * work is run only when the task exits the kernel and returns to user mode,
+ * or before entering guest mode. 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 the aforementioned transitions, or exits.
*
- * This is like the signal handler which runs in kernel mode, but it doesn't
- * try to wake up the @task.
+ * If the targeted task is exiting, then an error is returned and the work item
+ * is not queued. It's up to the caller to arrange for an alternative mechanism
+ * in that case.
*
- * Note: there is no ordering guarantee on works queued here.
+ * Note: there is no ordering guarantee on works queued here. The task_work
+ * list is LIFO.
*
* RETURNS:
* 0 if succeeds or -ESRCH.
*/
-int
-task_work_add(struct task_struct *task, struct callback_head *work, int notify)
+int task_work_add(struct task_struct *task, struct callback_head *work,
+ enum task_work_notify_mode notify)
{
struct callback_head *head;
unsigned long flags;
@@ -38,6 +43,8 @@ task_work_add(struct task_struct *task, struct callback_head *work, int notify)
} while (cmpxchg(&task->task_works, head, work) != head);
switch (notify) {
+ case TWA_NONE:
+ break;
case TWA_RESUME:
set_notify_resume(task);
break;
@@ -54,6 +61,9 @@ task_work_add(struct task_struct *task, struct callback_head *work, int notify)
unlock_task_sighand(task, &flags);
}
break;
+ default:
+ WARN_ON_ONCE(1);
+ break;
}
return 0;