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MINOR: tasks: Introduce __task_set_state_and_tid

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Introduce a new function, __task_set_state_and_tid, that atomically can
set a task's state and its tid. This will be used later, as the tid will
be used to indicate task ownership even for shared tasks.
This commit is contained in:
Olivier Houchard 2026-04-16 18:01:52 +02:00 committed by Olivier Houchard
parent 92206fb02f
commit 91f9e3a3dd
2 changed files with 61 additions and 0 deletions
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57
include/haproxy/task.h
View file

@ -205,6 +205,63 @@ static inline uint64_t task_mono_time(void)
return th_ctx->sched_call_date;
}
#if !defined(HA_CAS_IS_8B) && !defined(HA_HAVE_CAS_DW)
__decl_thread(extern HA_SPINLOCK_T task_state_tid);
#endif
static inline int __task_set_state_and_tid(struct task *t, int expected_tid, int new_tid, unsigned int current, unsigned int wanted)
{
#if defined(HA_CAS_IS_8B) || defined(HA_HAVE_CAS_DW)
uint64_t expected_value;
uint64_t new_value;
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
expected_value = ((uint64_t)(current) << 32) | (uint32_t)expected_tid;
#else
expected_value = current | ((uint64_t)expected_tid << 32);
#endif
do {
int tid_seen;
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
tid_seen = (expected_value & 0xffffffff);
if (tid_seen != expected_tid)
return 0;
if ((expected_value >> 32) != current)
return 0;
new_value = ((uint64_t)wanted << 32) | (uint32_t)new_tid;
#else
tid_seen = (expected_value >> 32);
if (tid_seen != expected_tid)
return 0;
if ((expected_value & 0xffffffff) != current)
return 0;
new_value = wanted | ((uint64_t)new_tid << 32);
#endif
#if defined(HA_CAS_IS_8B)
} while (!HA_ATOMIC_CAS((uint64_t *)&t->state, &expected_value, new_value) && __ha_cpu_relax());
#elif defined(HA_HAVE_CAS_DW)
} while (!HA_ATOMIC_DWCAS((uint64_t *)&t->state, &expected_value, &new_value) && __ha_cpu_relax());
#endif
return 1;
#else /* !HA_CAS_IS_8B && !HA_HAVE_CAS_DW */
int old_state;
int ret = 0;
HA_SPIN_LOCK(OTHER_LOCK, &task_state_tid);
if (_HA_ATOMIC_LOAD(&t->tid) == expected_tid) {
old_state = _HA_ATOMIC_LOAD(&t->state);
if (old_state == current && HA_ATOMIC_CAS(&t->state, &old_state, wanted)) {
_HA_ATOMIC_STORE(&t->tid, new_tid);
ret = 1;
}
}
HA_SPIN_UNLOCK(OTHER_LOCK, &task_state_tid);
return ret;
#endif
}
/* puts the task <t> in run queue with reason flags <f>, and returns <t> */
/* This will put the task in the local runqueue if the task is only runnable
* by the current thread, in the global runqueue otherwies. With DEBUG_TASK,

4
src/task.c
View file

@ -47,6 +47,10 @@ static struct {
int sched_stuck THREAD_ALIGNED();
} sched_ctx[MAX_THREADS];
#if !defined(HA_CAS_IS_8B) && !defined(HA_HAVE_CAS_DW)
__decl_thread(HA_SPINLOCK_T task_state_tid);
#endif
/* Flags the task <t> for immediate destruction and puts it into its first
* thread's shared tasklet list if not yet queued/running. This will bypass
* the priority scheduling and make the task show up as fast as possible in