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

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