mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-22 21:32:06 +07:00
e73f8959af
Provide a simple mechanism that allows running code in the (nonatomic) context of the arbitrary task. The caller does task_work_add(task, task_work) and this task executes task_work->func() either from do_notify_resume() or from do_exit(). The callback can rely on PF_EXITING to detect the latter case. "struct task_work" can be embedded in another struct, still it has "void *data" to handle the most common/simple case. This allows us to kill the ->replacement_session_keyring hack, and potentially this can have more users. Performance-wise, this adds 2 "unlikely(!hlist_empty())" checks into tracehook_notify_resume() and do_exit(). But at the same time we can remove the "replacement_session_keyring != NULL" checks from arch/*/signal.c and exit_creds(). Note: task_work_add/task_work_run abuses ->pi_lock. This is only because this lock is already used by lookup_pi_state() to synchronize with do_exit() setting PF_EXITING. Fortunately the scope of this lock in task_work.c is really tiny, and the code is unlikely anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Alexander Gordeev <agordeev@redhat.com> Cc: Chris Zankel <chris@zankel.net> Cc: David Smith <dsmith@redhat.com> Cc: "Frank Ch. Eigler" <fche@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
85 lines
2.0 KiB
C
85 lines
2.0 KiB
C
#include <linux/spinlock.h>
|
|
#include <linux/task_work.h>
|
|
#include <linux/tracehook.h>
|
|
|
|
int
|
|
task_work_add(struct task_struct *task, struct task_work *twork, bool notify)
|
|
{
|
|
unsigned long flags;
|
|
int err = -ESRCH;
|
|
|
|
#ifndef TIF_NOTIFY_RESUME
|
|
if (notify)
|
|
return -ENOTSUPP;
|
|
#endif
|
|
/*
|
|
* We must not insert the new work if the task has already passed
|
|
* exit_task_work(). We rely on do_exit()->raw_spin_unlock_wait()
|
|
* and check PF_EXITING under pi_lock.
|
|
*/
|
|
raw_spin_lock_irqsave(&task->pi_lock, flags);
|
|
if (likely(!(task->flags & PF_EXITING))) {
|
|
hlist_add_head(&twork->hlist, &task->task_works);
|
|
err = 0;
|
|
}
|
|
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
|
|
|
|
/* test_and_set_bit() implies mb(), see tracehook_notify_resume(). */
|
|
if (likely(!err) && notify)
|
|
set_notify_resume(task);
|
|
return err;
|
|
}
|
|
|
|
struct task_work *
|
|
task_work_cancel(struct task_struct *task, task_work_func_t func)
|
|
{
|
|
unsigned long flags;
|
|
struct task_work *twork;
|
|
struct hlist_node *pos;
|
|
|
|
raw_spin_lock_irqsave(&task->pi_lock, flags);
|
|
hlist_for_each_entry(twork, pos, &task->task_works, hlist) {
|
|
if (twork->func == func) {
|
|
hlist_del(&twork->hlist);
|
|
goto found;
|
|
}
|
|
}
|
|
twork = NULL;
|
|
found:
|
|
raw_spin_unlock_irqrestore(&task->pi_lock, flags);
|
|
|
|
return twork;
|
|
}
|
|
|
|
void task_work_run(void)
|
|
{
|
|
struct task_struct *task = current;
|
|
struct hlist_head task_works;
|
|
struct hlist_node *pos;
|
|
|
|
raw_spin_lock_irq(&task->pi_lock);
|
|
hlist_move_list(&task->task_works, &task_works);
|
|
raw_spin_unlock_irq(&task->pi_lock);
|
|
|
|
if (unlikely(hlist_empty(&task_works)))
|
|
return;
|
|
/*
|
|
* We use hlist to save the space in task_struct, but we want fifo.
|
|
* Find the last entry, the list should be short, then process them
|
|
* in reverse order.
|
|
*/
|
|
for (pos = task_works.first; pos->next; pos = pos->next)
|
|
;
|
|
|
|
for (;;) {
|
|
struct hlist_node **pprev = pos->pprev;
|
|
struct task_work *twork = container_of(pos, struct task_work,
|
|
hlist);
|
|
twork->func(twork);
|
|
|
|
if (pprev == &task_works.first)
|
|
break;
|
|
pos = container_of(pprev, struct hlist_node, next);
|
|
}
|
|
}
|