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MEDIUM: task: implement tasklet kill 

Implement an equivalent of task_kill for tasklets. This function can be
used to request a tasklet deletion in a thread-safe way.

Currently this function is unused.
This commit is contained in:
Amaury Denoyelle 2021-07-28 16:12:57 +02:00
parent c755efd5c6
commit 7b368339af
2 changed files with 50 additions and 2 deletions
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1
include/haproxy/task.h
View File

@ -107,6 +107,7 @@ __decl_thread(extern HA_RWLOCK_T wq_lock); /* RW lock related to the wait que
void __tasklet_wakeup_on(struct tasklet *tl, int thr);
void task_kill(struct task *t);
void tasklet_kill(struct tasklet *t);
void __task_wakeup(struct task *t);
void __task_queue(struct task *task, struct eb_root *wq);

51
src/task.c
View File

@ -103,6 +103,44 @@ void task_kill(struct task *t)
}
}
/* Equivalent of task_kill for tasklets. Mark the tasklet <t> for destruction.
* It will be deleted on the next scheduler invocation. This function is
* thread-safe : a thread can kill a tasklet of another thread.
*/
void tasklet_kill(struct tasklet *t)
{
unsigned int state = t->state;
unsigned int thr;
BUG_ON(state & TASK_KILLED);
while (1) {
while (state & (TASK_IN_LIST)) {
/* Tasklet already in the list ready to be executed. Add
* the killed flag and wait for the process loop to
* detect it.
*/
if (_HA_ATOMIC_CAS(&t->state, &state, state | TASK_KILLED))
return;
}
/* Mark the tasklet as killed and wake the thread to process it
* as soon as possible.
*/
if (_HA_ATOMIC_CAS(&t->state, &state, state | TASK_IN_LIST | TASK_KILLED)) {
thr = t->tid > 0 ? t->tid: tid;
MT_LIST_APPEND(&task_per_thread[thr].shared_tasklet_list,
(struct mt_list *)&t->list);
_HA_ATOMIC_INC(&task_per_thread[thr].rq_total);
if (sleeping_thread_mask & (1UL << thr)) {
_HA_ATOMIC_AND(&sleeping_thread_mask, ~(1UL << thr));
wake_thread(thr);
}
return;
}
}
}
/* Do not call this one, please use tasklet_wakeup_on() instead, as this one is
* the slow path of tasklet_wakeup_on() which performs some preliminary checks
* and sets TASK_IN_LIST before calling this one. A negative <thr> designates
@ -485,7 +523,7 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
budgets[queue]--;
t = (struct task *)LIST_ELEM(tl_queues[queue].n, struct tasklet *, list);
state = t->state & (TASK_SHARED_WQ|TASK_SELF_WAKING|TASK_HEAVY|TASK_F_TASKLET|TASK_KILLED|TASK_F_USR1);
state = t->state & (TASK_SHARED_WQ|TASK_SELF_WAKING|TASK_HEAVY|TASK_F_TASKLET|TASK_KILLED|TASK_F_USR1|TASK_KILLED);
ti->flags &= ~TI_FL_STUCK; // this thread is still running
activity[tid].ctxsw++;
@ -516,7 +554,16 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
state = _HA_ATOMIC_XCHG(&t->state, state);
__ha_barrier_atomic_store();
process(t, ctx, state);
if (likely(!(state & TASK_KILLED))) {
process(t, ctx, state);
}
else {
done++;
sched->current = NULL;
pool_free(pool_head_tasklet, t);
__ha_barrier_store();
continue;
}
if (unlikely(task_profiling_mask & tid_bit)) {
HA_ATOMIC_INC(&profile_entry->calls);