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kbdmux(4): Make callout handler mpsafe.

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Both callout and taskqueue now have drain() routines not requiring
external locking.  It allows to remove TASK flag and manual drain,
so the only thing remaining for lock to protect inside the callout
handler is ks_inq_length zero comparison, that can be lockless.

MFC after:	2 weeks

(cherry picked from commit e5018628e7)
This commit is contained in:
Alexander Motin 2021-08-08 18:19:08 -04:00
parent 4c6246b76e
commit 66e088e12b
1 changed files with 10 additions and 51 deletions
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61
sys/dev/kbdmux/kbdmux.c
View file

@ -105,12 +105,6 @@ MALLOC_DEFINE(M_KBDMUX, KEYBOARD_NAME, "Keyboard multiplexor");
mtx_unlock(&(s)->ks_lock)
#define KBDMUX_LOCK_ASSERT(s, w) \
mtx_assert(&(s)->ks_lock, (w))
#define KBDMUX_SLEEP(s, f, d, t) \
msleep(&(s)->f, &(s)->ks_lock, PCATCH | (PZERO + 1), (d), (t))
#define KBDMUX_CALLOUT_INIT(s) \
callout_init_mtx(&(s)->ks_timo, &(s)->ks_lock, 0)
#define KBDMUX_QUEUE_INTR(s) \
taskqueue_enqueue(taskqueue_swi_giant, &(s)->ks_task)
#else
#define KBDMUX_LOCK_DECL_GLOBAL
@ -124,12 +118,6 @@ MALLOC_DEFINE(M_KBDMUX, KEYBOARD_NAME, "Keyboard multiplexor");
#define KBDMUX_LOCK_ASSERT(s, w)
#define KBDMUX_SLEEP(s, f, d, t) \
tsleep(&(s)->f, PCATCH | (PZERO + 1), (d), (t))
#define KBDMUX_CALLOUT_INIT(s) \
callout_init(&(s)->ks_timo, 0)
#define KBDMUX_QUEUE_INTR(s) \
taskqueue_enqueue(taskqueue_swi_giant, &(s)->ks_task)
#endif /* not yet */
/*
@ -157,7 +145,6 @@ struct kbdmux_state
int ks_flags; /* flags */
#define COMPOSE (1 << 0) /* compose char flag */
#define TASK (1 << 2) /* interrupt task queued */
int ks_polling; /* poll nesting count */
int ks_mode; /* K_XLATE, K_RAW, K_CODE */
@ -223,16 +210,8 @@ void
kbdmux_kbd_intr(void *xkbd, int pending)
{
keyboard_t *kbd = (keyboard_t *) xkbd;
kbdmux_state_t *state = (kbdmux_state_t *) kbd->kb_data;
kbdd_intr(kbd, NULL);
KBDMUX_LOCK(state);
state->ks_flags &= ~TASK;
wakeup(&state->ks_task);
KBDMUX_UNLOCK(state);
}
/*
@ -243,23 +222,12 @@ kbdmux_kbd_intr_timo(void *xstate)
{
kbdmux_state_t *state = (kbdmux_state_t *) xstate;
KBDMUX_LOCK_ASSERT(state, MA_OWNED);
if (callout_pending(&state->ks_timo))
return; /* callout was reset */
if (!callout_active(&state->ks_timo))
return; /* callout was stopped */
callout_deactivate(&state->ks_timo);
/* queue interrupt task if needed */
if (state->ks_inq_length > 0 && !(state->ks_flags & TASK) &&
KBDMUX_QUEUE_INTR(state) == 0)
state->ks_flags |= TASK;
if (state->ks_inq_length > 0)
taskqueue_enqueue(taskqueue_swi_giant, &state->ks_task);
/* re-schedule timeout */
callout_reset(&state->ks_timo, TICKS, kbdmux_kbd_intr_timo, state);
callout_schedule(&state->ks_timo, TICKS);
}
/*
@ -299,9 +267,8 @@ kbdmux_kbd_event(keyboard_t *kbd, int event, void *arg)
}
/* queue interrupt task if needed */
if (state->ks_inq_length > 0 && !(state->ks_flags & TASK) &&
KBDMUX_QUEUE_INTR(state) == 0)
state->ks_flags |= TASK;
if (state->ks_inq_length > 0)
taskqueue_enqueue(taskqueue_swi_giant, &state->ks_task);
KBDMUX_UNLOCK(state);
} break;
@ -444,7 +411,7 @@ kbdmux_init(int unit, keyboard_t **kbdp, void *arg, int flags)
KBDMUX_LOCK_INIT(state);
TASK_INIT(&state->ks_task, 0, kbdmux_kbd_intr, (void *) kbd);
KBDMUX_CALLOUT_INIT(state);
callout_init(&state->ks_timo, 1);
SLIST_INIT(&state->ks_kbds);
} else if (KBD_IS_INITIALIZED(*kbdp) && KBD_IS_CONFIGURED(*kbdp)) {
return (0);
@ -521,9 +488,7 @@ kbdmux_init(int unit, keyboard_t **kbdp, void *arg, int flags)
KBD_CONFIG_DONE(kbd);
KBDMUX_LOCK(state);
callout_reset(&state->ks_timo, TICKS, kbdmux_kbd_intr_timo, state);
KBDMUX_UNLOCK(state);
}
return (0);
@ -555,16 +520,8 @@ kbdmux_term(keyboard_t *kbd)
kbdmux_state_t *state = (kbdmux_state_t *) kbd->kb_data;
kbdmux_kbd_t *k;
KBDMUX_LOCK(state);
/* kill callout */
callout_stop(&state->ks_timo);
/* wait for interrupt task */
while (state->ks_flags & TASK)
KBDMUX_SLEEP(state, ks_task, "kbdmuxc", 0);
/* release all keyboards from the mux */
KBDMUX_LOCK(state);
while ((k = SLIST_FIRST(&state->ks_kbds)) != NULL) {
kbd_release(k->kbd, &k->kbd);
SLIST_REMOVE_HEAD(&state->ks_kbds, next);
@ -573,9 +530,11 @@ kbdmux_term(keyboard_t *kbd)
free(k, M_KBDMUX);
}
KBDMUX_UNLOCK(state);
callout_drain(&state->ks_timo);
taskqueue_drain(taskqueue_swi_giant, &state->ks_task);
kbd_unregister(kbd);
#ifdef EVDEV_SUPPORT