usb/gadget/NCM: Replace tasklet with softirq hrtimer

The tx_tasklet tasklet is used in invoke the hrtimer (task_timer) in
softirq context. This can be also achieved without the tasklet but
with HRTIMER_MODE_SOFT as hrtimer mode.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: keescook@chromium.org
Cc: linux-usb@vger.kernel.org
Link: http://lkml.kernel.org/r/20171221104205.7269-36-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c
index c5bce8e2298312bf2c73edc37f80af72b03ae34e..5780fba620ab13014369ec0304910d9ee317e1bf 100644 (file)
--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -73,9 +73,7 @@ struct f_ncm {
        struct sk_buff                  *skb_tx_ndp;
        u16                             ndp_dgram_count;
        bool                            timer_force_tx;
-       struct tasklet_struct           tx_tasklet;
        struct hrtimer                  task_timer;
-
        bool                            timer_stopping;
 };
 
@@ -1104,7 +1102,7 @@ static struct sk_buff *ncm_wrap_ntb(struct gether *port,
 
                /* Delay the timer. */
                hrtimer_start(&ncm->task_timer, TX_TIMEOUT_NSECS,
-                             HRTIMER_MODE_REL);
+                             HRTIMER_MODE_REL_SOFT);
 
                /* Add the datagram position entries */
                ntb_ndp = skb_put_zero(ncm->skb_tx_ndp, dgram_idx_len);
@@ -1148,17 +1146,15 @@ err:
 }
 
 /*
- * This transmits the NTB if there are frames waiting.
+ * The transmit should only be run if no skb data has been sent
+ * for a certain duration.
  */
-static void ncm_tx_tasklet(unsigned long data)
+static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
 {
-       struct f_ncm    *ncm = (void *)data;
-
-       if (ncm->timer_stopping)
-               return;
+       struct f_ncm *ncm = container_of(data, struct f_ncm, task_timer);
 
        /* Only send if data is available. */
-       if (ncm->skb_tx_data) {
+       if (!ncm->timer_stopping && ncm->skb_tx_data) {
                ncm->timer_force_tx = true;
 
                /* XXX This allowance of a NULL skb argument to ndo_start_xmit
@@ -1171,16 +1167,6 @@ static void ncm_tx_tasklet(unsigned long data)
 
                ncm->timer_force_tx = false;
        }
-}
-
-/*
- * The transmit should only be run if no skb data has been sent
- * for a certain duration.
- */
-static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
-{
-       struct f_ncm *ncm = container_of(data, struct f_ncm, task_timer);
-       tasklet_schedule(&ncm->tx_tasklet);
        return HRTIMER_NORESTART;
 }
 
@@ -1513,8 +1499,7 @@ static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
        ncm->port.open = ncm_open;
        ncm->port.close = ncm_close;
 
-       tasklet_init(&ncm->tx_tasklet, ncm_tx_tasklet, (unsigned long) ncm);
-       hrtimer_init(&ncm->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+       hrtimer_init(&ncm->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
        ncm->task_timer.function = ncm_tx_timeout;
 
        DBG(cdev, "CDC Network: %s speed IN/%s OUT/%s NOTIFY/%s\n",
@@ -1623,7 +1608,6 @@ static void ncm_unbind(struct usb_configuration *c, struct usb_function *f)
        DBG(c->cdev, "ncm unbind\n");
 
        hrtimer_cancel(&ncm->task_timer);
-       tasklet_kill(&ncm->tx_tasklet);
 
        ncm_string_defs[0].id = 0;
        usb_free_all_descriptors(f);