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Fix for regression issue in USB keyboard driver after r304735.

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A series of zero delay callouts can happen causing high CPU usage of the
timer subsystem when trying to repeat keys, because the time of the
absolute timeout is not moving forward. The condition clears when all
keys are released.

Reported by:	Johannes Lundberg <johalun0@gmail.com>
Discussed with:	bde@
PR:		226968
MFC after:	1 week
Sponsored by:	Mellanox Technologies
This commit is contained in:
Hans Petter Selasky 2018-03-28 17:39:23 +00:00
parent 779f392b84
commit 6e78686239
1 changed files with 17 additions and 13 deletions
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30
sys/dev/usb/input/ukbd.c
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@ -386,10 +386,22 @@ ukbd_any_key_pressed(struct ukbd_softc *sc)
static void
ukbd_start_timer(struct ukbd_softc *sc)
{
sbintime_t delay, prec;
sbintime_t delay, now, prec;
now = sbinuptime();
/* check if initial delay passed and fallback to key repeat delay */
if (sc->sc_delay == 0)
sc->sc_delay = sc->sc_kbd.kb_delay2;
/* compute timeout */
delay = SBT_1MS * sc->sc_delay;
sc->sc_co_basetime += delay;
/* check if we are running behind */
if (sc->sc_co_basetime < now)
sc->sc_co_basetime = now;
/* This is rarely called, so prefer precision to efficiency. */
prec = qmin(delay >> 7, SBT_1MS * 10);
usb_callout_reset_sbt(&sc->sc_callout, sc->sc_co_basetime, prec,
@ -510,7 +522,6 @@ ukbd_get_key(struct ukbd_softc *sc, uint8_t wait)
static void
ukbd_interrupt(struct ukbd_softc *sc)
{
struct timeval ctv;
uint32_t n_mod;
uint32_t o_mod;
uint32_t now = sc->sc_time_ms;
@ -580,14 +591,11 @@ rfound: ;
break;
}
}
if (j < UKBD_NKEYCODE) {
/* Old key repeating. */
sc->sc_delay = sc->sc_kbd.kb_delay2;
} else {
/* New key. */
microuptime(&ctv);
sc->sc_co_basetime = tvtosbt(ctv);
if (j == UKBD_NKEYCODE) {
/* New key - set initial delay and [re]start timer */
sc->sc_co_basetime = sbinuptime();
sc->sc_delay = sc->sc_kbd.kb_delay1;
ukbd_start_timer(sc);
}
ukbd_put_key(sc, key | KEY_PRESS);
@ -838,10 +846,6 @@ ukbd_intr_callback(struct usb_xfer *xfer, usb_error_t error)
ukbd_interrupt(sc);
if (ukbd_any_key_pressed(sc) != 0) {
ukbd_start_timer(sc);
}
case USB_ST_SETUP:
tr_setup:
if (sc->sc_inputs < UKBD_IN_BUF_FULL) {