Re: [PATCH v2 30/37] can/bcm: Replace hrtimer_tasklet with softirq based hrtimer

Oliver Hartkopp
2017-10-27T14:43:08Z

On 10/22/2017 11:40 PM, Anna-Maria Gleixner wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> Switch the timer to HRTIMER_MODE_SOFT, which executed the timer
> callback in softirq context and remove the hrtimer_tasklet.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> Cc: Oliver Hartkopp <socketcan@hartkopp.net>

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>

> Cc: Marc Kleine-Budde <mkl@pengutronix.de>
> Cc: linux-can@vger.kernel.org
> ---
> net/can/bcm.c | 156 +++++++++++++++++++---------------------------------------
> 1 file changed, 52 insertions(+), 104 deletions(-)
>
> --- a/net/can/bcm.c
> +++ b/net/can/bcm.c
> @@ -102,7 +102,6 @@ struct bcm_op {
> unsigned long frames_abs, frames_filtered;
> struct bcm_timeval ival1, ival2;
> struct hrtimer timer, thrtimer;
> - struct tasklet_struct tsklet, thrtsklet;
> ktime_t rx_stamp, kt_ival1, kt_ival2, kt_lastmsg;
> int rx_ifindex;
> int cfsiz;
> @@ -364,25 +363,34 @@ static void bcm_send_to_user(struct bcm_
> }
> }
>
> -static void bcm_tx_start_timer(struct bcm_op *op)
> +static bool bcm_tx_set_expiry(struct bcm_op *op, struct hrtimer *hrt)
> {
> + ktime_t ival;
> +
> if (op->kt_ival1 && op->count)
> - hrtimer_start(&op->timer,
> - ktime_add(ktime_get(), op->kt_ival1),
> - HRTIMER_MODE_ABS);
> + ival = op->kt_ival1;
> else if (op->kt_ival2)
> - hrtimer_start(&op->timer,
> - ktime_add(ktime_get(), op->kt_ival2),
> - HRTIMER_MODE_ABS);
> + ival = op->kt_ival2;
> + else
> + return false;
> +
> + hrtimer_set_expires(hrt, ktime_add(ktime_get(), ival));
> + return true;
> }
>
> -static void bcm_tx_timeout_tsklet(unsigned long data)
> +static void bcm_tx_start_timer(struct bcm_op *op)
> {
> - struct bcm_op *op = (struct bcm_op *)data;
> + if (bcm_tx_set_expiry(op, &op->timer))
> + hrtimer_start_expires(&op->timer, HRTIMER_MODE_ABS_SOFT);
> +}
> +
> +/* bcm_tx_timeout_handler - performs cyclic CAN frame transmissions */
> +static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)
> +{
> + struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
> struct bcm_msg_head msg_head;
>
> if (op->kt_ival1 && (op->count > 0)) {
> -
> op->count--;
> if (!op->count && (op->flags & TX_COUNTEVT)) {
>
> @@ -399,22 +407,12 @@ static void bcm_tx_timeout_tsklet(unsign
> }
> bcm_can_tx(op);
>
> - } else if (op->kt_ival2)
> + } else if (op->kt_ival2) {
> bcm_can_tx(op);
> + }
>
> - bcm_tx_start_timer(op);
> -}
> -
> -/*
> - * bcm_tx_timeout_handler - performs cyclic CAN frame transmissions
> - */
> -static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)
> -{
> - struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
> -
> - tasklet_schedule(&op->tsklet);
> -
> - return HRTIMER_NORESTART;
> + return bcm_tx_set_expiry(op, &op->timer) ?
> + HRTIMER_RESTART : HRTIMER_NORESTART;
> }
>
> /*
> @@ -480,7 +478,7 @@ static void bcm_rx_update_and_send(struc
> /* do not send the saved data - only start throttle timer */
> hrtimer_start(&op->thrtimer,
> ktime_add(op->kt_lastmsg, op->kt_ival2),
> - HRTIMER_MODE_ABS);
> + HRTIMER_MODE_ABS_SOFT);
> return;
> }
>
> @@ -539,14 +537,21 @@ static void bcm_rx_starttimer(struct bcm
> return;
>
> if (op->kt_ival1)
> - hrtimer_start(&op->timer, op->kt_ival1, HRTIMER_MODE_REL);
> + hrtimer_start(&op->timer, op->kt_ival1, HRTIMER_MODE_REL_SOFT);
> }
>
> -static void bcm_rx_timeout_tsklet(unsigned long data)
> +/* bcm_rx_timeout_handler - when the (cyclic) CAN frame reception timed out */
> +static enum hrtimer_restart bcm_rx_timeout_handler(struct hrtimer *hrtimer)
> {
> - struct bcm_op *op = (struct bcm_op *)data;
> + struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
> struct bcm_msg_head msg_head;
>
> + /* if user wants to be informed, when cyclic CAN-Messages come back */
> + if ((op->flags & RX_ANNOUNCE_RESUME) && op->last_frames) {
> + /* clear received CAN frames to indicate 'nothing received' */
> + memset(op->last_frames, 0, op->nframes * op->cfsiz);
> + }
> +
> /* create notification to user */
> msg_head.opcode = RX_TIMEOUT;
> msg_head.flags = op->flags;
> @@ -557,25 +562,6 @@ static void bcm_rx_timeout_tsklet(unsign
> msg_head.nframes = 0;
>
> bcm_send_to_user(op, &msg_head, NULL, 0);
> -}
> -
> -/*
> - * bcm_rx_timeout_handler - when the (cyclic) CAN frame reception timed out
> - */
> -static enum hrtimer_restart bcm_rx_timeout_handler(struct hrtimer *hrtimer)
> -{
> - struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);
> -
> - /* schedule before NET_RX_SOFTIRQ */
> - tasklet_hi_schedule(&op->tsklet);
> -
> - /* no restart of the timer is done here! */
> -
> - /* if user wants to be informed, when cyclic CAN-Messages come back */
> - if ((op->flags & RX_ANNOUNCE_RESUME) && op->last_frames) {
> - /* clear received CAN frames to indicate 'nothing received' */
> - memset(op->last_frames, 0, op->nframes * op->cfsiz);
> - }
>
> return HRTIMER_NORESTART;
> }
> @@ -583,14 +569,12 @@ static enum hrtimer_restart bcm_rx_timeo
> /*
> * bcm_rx_do_flush - helper for bcm_rx_thr_flush
> */
> -static inline int bcm_rx_do_flush(struct bcm_op *op, int update,
> - unsigned int index)
> +static inline int bcm_rx_do_flush(struct bcm_op *op, unsigned int index)
> {
> struct canfd_frame *lcf = op->last_frames + op->cfsiz * index;
>
> if ((op->last_frames) && (lcf->flags & RX_THR)) {
> - if (update)
> - bcm_rx_changed(op, lcf);
> + bcm_rx_changed(op, lcf);
> return 1;
> }
> return 0;
> @@ -598,11 +582,8 @@ static inline int bcm_rx_do_flush(struct
>
> /*
> * bcm_rx_thr_flush - Check for throttled data and send it to the userspace
> - *
> - * update == 0 : just check if throttled data is available (any irq context)
> - * update == 1 : check and send throttled data to userspace (soft_irq context)
> */
> -static int bcm_rx_thr_flush(struct bcm_op *op, int update)
> +static int bcm_rx_thr_flush(struct bcm_op *op)
> {
> int updated = 0;
>
> @@ -611,24 +592,16 @@ static int bcm_rx_thr_flush(struct bcm_o
>
> /* for MUX filter we start at index 1 */
> for (i = 1; i < op->nframes; i++)
> - updated += bcm_rx_do_flush(op, update, i);
> + updated += bcm_rx_do_flush(op, i);
>
> } else {
> /* for RX_FILTER_ID and simple filter */
> - updated += bcm_rx_do_flush(op, update, 0);
> + updated += bcm_rx_do_flush(op, 0);
> }
>
> return updated;
> }
>
> -static void bcm_rx_thr_tsklet(unsigned long data)
> -{
> - struct bcm_op *op = (struct bcm_op *)data;
> -
> - /* push the changed data to the userspace */
> - bcm_rx_thr_flush(op, 1);
> -}
> -
> /*
> * bcm_rx_thr_handler - the time for blocked content updates is over now:
> * Check for throttled data and send it to the userspace
> @@ -637,9 +610,7 @@ static enum hrtimer_restart bcm_rx_thr_h
> {
> struct bcm_op *op = container_of(hrtimer, struct bcm_op, thrtimer);
>
> - tasklet_schedule(&op->thrtsklet);
> -
> - if (bcm_rx_thr_flush(op, 0)) {
> + if (bcm_rx_thr_flush(op)) {
> hrtimer_forward(hrtimer, ktime_get(), op->kt_ival2);
> return HRTIMER_RESTART;
> } else {
> @@ -735,23 +706,8 @@ static struct bcm_op *bcm_find_op(struct
>
> static void bcm_remove_op(struct bcm_op *op)
> {
> - if (op->tsklet.func) {
> - while (test_bit(TASKLET_STATE_SCHED, &op->tsklet.state) ||
> - test_bit(TASKLET_STATE_RUN, &op->tsklet.state) ||
> - hrtimer_active(&op->timer)) {
> - hrtimer_cancel(&op->timer);
> - tasklet_kill(&op->tsklet);
> - }
> - }
> -
> - if (op->thrtsklet.func) {
> - while (test_bit(TASKLET_STATE_SCHED, &op->thrtsklet.state) ||
> - test_bit(TASKLET_STATE_RUN, &op->thrtsklet.state) ||
> - hrtimer_active(&op->thrtimer)) {
> - hrtimer_cancel(&op->thrtimer);
> - tasklet_kill(&op->thrtsklet);
> - }
> - }
> + hrtimer_cancel(&op->timer);
> + hrtimer_cancel(&op->thrtimer);
>
> if ((op->frames) && (op->frames != &op->sframe))
> kfree(op->frames);
> @@ -979,15 +935,13 @@ static int bcm_tx_setup(struct bcm_msg_h
> op->ifindex = ifindex;
>
> /* initialize uninitialized (kzalloc) structure */
> - hrtimer_init(&op->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + hrtimer_init(&op->timer, CLOCK_MONOTONIC,
> + HRTIMER_MODE_REL_SOFT);
> op->timer.function = bcm_tx_timeout_handler;
>
> - /* initialize tasklet for tx countevent notification */
> - tasklet_init(&op->tsklet, bcm_tx_timeout_tsklet,
> - (unsigned long) op);
> -
> /* currently unused in tx_ops */
> - hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC,
> + HRTIMER_MODE_REL_SOFT);
>
> /* add this bcm_op to the list of the tx_ops */
> list_add(&op->list, &bo->tx_ops);
> @@ -1150,20 +1104,14 @@ static int bcm_rx_setup(struct bcm_msg_h
> op->rx_ifindex = ifindex;
>
> /* initialize uninitialized (kzalloc) structure */
> - hrtimer_init(&op->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + hrtimer_init(&op->timer, CLOCK_MONOTONIC,
> + HRTIMER_MODE_REL_SOFT);
> op->timer.function = bcm_rx_timeout_handler;
>
> - /* initialize tasklet for rx timeout notification */
> - tasklet_init(&op->tsklet, bcm_rx_timeout_tsklet,
> - (unsigned long) op);
> -
> - hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + hrtimer_init(&op->thrtimer, CLOCK_MONOTONIC,
> + HRTIMER_MODE_REL_SOFT);
> op->thrtimer.function = bcm_rx_thr_handler;
>
> - /* initialize tasklet for rx throttle handling */
> - tasklet_init(&op->thrtsklet, bcm_rx_thr_tsklet,
> - (unsigned long) op);
> -
> /* add this bcm_op to the list of the rx_ops */
> list_add(&op->list, &bo->rx_ops);
>
> @@ -1209,12 +1157,12 @@ static int bcm_rx_setup(struct bcm_msg_h
> */
> op->kt_lastmsg = 0;
> hrtimer_cancel(&op->thrtimer);
> - bcm_rx_thr_flush(op, 1);
> + bcm_rx_thr_flush(op);
> }
>
> if ((op->flags & STARTTIMER) && op->kt_ival1)
> hrtimer_start(&op->timer, op->kt_ival1,
> - HRTIMER_MODE_REL);
> + HRTIMER_MODE_REL_SOFT);
> }
>
> /* now we can register for can_ids, if we added a new bcm_op */
>
>