[media] lirc_zilog: Update IR Rx polling kthread start/stop and some printks

The IR Rx polling thread was originally a kernel_thread long ago,
and had only been minimally converted to a kthread.  This patch
finishes that conversion by

- cleaning up all the unneeded completions

- destroying the kthread properly by calling kthread_stop()

- changing lirc_thread() to test kthread_should_stop() just before
	every point where it may sleep

- reorganizing the lirc_thread() function so it uses fewer lines

- modifying the name of the kthread from "lirc_zilog" to
	"zilog-rx-i2c-N", so ps will show which kthread polls
	which Zilog Z8 IR unit.

Also some minor tweaks were made to logging emitted by the
ir_probe() function.

Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/staging/lirc/lirc_zilog.c b/drivers/staging/lirc/lirc_zilog.c
index f2e8c63fa5bd0c03bfb7cddc36f613c2dc7747b2..f7aa5e4e98b383c971512a7edacf8d8754c56d52 100644 (file)
--- a/drivers/staging/lirc/lirc_zilog.c
+++ b/drivers/staging/lirc/lirc_zilog.c
@@ -69,9 +69,6 @@ struct IR_rx {
        struct mutex buf_lock;
 
        /* RX polling thread data */
-       struct completion *t_notify;
-       struct completion *t_notify2;
-       int shutdown;
        struct task_struct *task;
 
        /* RX read data */
@@ -171,12 +168,20 @@ static int add_to_buf(struct IR *ir)
         * data and we have space
         */
        do {
+               if (kthread_should_stop())
+                       return -ENODATA;
+
                /*
                 * Lock i2c bus for the duration.  RX/TX chips interfere so
                 * this is worth it
                 */
                mutex_lock(&ir->ir_lock);
 
+               if (kthread_should_stop()) {
+                       mutex_unlock(&ir->ir_lock);
+                       return -ENODATA;
+               }
+
                /*
                 * Send random "poll command" (?)  Windows driver does this
                 * and it is a good point to detect chip failure.
@@ -196,6 +201,10 @@ static int add_to_buf(struct IR *ir)
                                    "trying reset\n");
 
                        set_current_state(TASK_UNINTERRUPTIBLE);
+                       if (kthread_should_stop()) {
+                               mutex_unlock(&ir->ir_lock);
+                               return -ENODATA;
+                       }
                        schedule_timeout((100 * HZ + 999) / 1000);
                        if (ir->tx != NULL)
                                ir->tx->need_boot = 1;
@@ -205,6 +214,10 @@ static int add_to_buf(struct IR *ir)
                        continue;
                }
 
+               if (kthread_should_stop()) {
+                       mutex_unlock(&ir->ir_lock);
+                       return -ENODATA;
+               }
                ret = i2c_master_recv(rx->c, keybuf, sizeof(keybuf));
                mutex_unlock(&ir->ir_lock);
                if (ret != sizeof(keybuf)) {
@@ -255,48 +268,35 @@ static int lirc_thread(void *arg)
        struct IR *ir = arg;
        struct IR_rx *rx = ir->rx;
 
-       if (rx->t_notify != NULL)
-               complete(rx->t_notify);
-
        dprintk("poll thread started\n");
 
-       do {
-               if (ir->open) {
-                       set_current_state(TASK_INTERRUPTIBLE);
+       while (!kthread_should_stop()) {
+               set_current_state(TASK_INTERRUPTIBLE);
 
-                       /*
-                        * This is ~113*2 + 24 + jitter (2*repeat gap +
-                        * code length).  We use this interval as the chip
-                        * resets every time you poll it (bad!).  This is
-                        * therefore just sufficient to catch all of the
-                        * button presses.  It makes the remote much more
-                        * responsive.  You can see the difference by
-                        * running irw and holding down a button.  With
-                        * 100ms, the old polling interval, you'll notice
-                        * breaks in the repeat sequence corresponding to
-                        * lost keypresses.
-                        */
-                       schedule_timeout((260 * HZ) / 1000);
-                       if (rx->shutdown)
-                               break;
-                       if (!add_to_buf(ir))
-                               wake_up_interruptible(&rx->buf.wait_poll);
-               } else {
-                       /* if device not opened so we can sleep half a second */
-                       set_current_state(TASK_INTERRUPTIBLE);
+               /* if device not opened, we can sleep half a second */
+               if (!ir->open) {
                        schedule_timeout(HZ/2);
+                       continue;
                }
-       } while (!rx->shutdown);
 
-       if (rx->t_notify2 != NULL)
-               wait_for_completion(rx->t_notify2);
-
-       rx->task = NULL;
-       if (rx->t_notify != NULL)
-               complete(rx->t_notify);
+               /*
+                * This is ~113*2 + 24 + jitter (2*repeat gap + code length).
+                * We use this interval as the chip resets every time you poll
+                * it (bad!).  This is therefore just sufficient to catch all
+                * of the button presses.  It makes the remote much more
+                * responsive.  You can see the difference by running irw and
+                * holding down a button.  With 100ms, the old polling
+                * interval, you'll notice breaks in the repeat sequence
+                * corresponding to lost keypresses.
+                */
+               schedule_timeout((260 * HZ) / 1000);
+               if (kthread_should_stop())
+                       break;
+               if (!add_to_buf(ir))
+                       wake_up_interruptible(&rx->buf.wait_poll);
+       }
 
        dprintk("poll thread ended\n");
-       /* FIXME - investigate if this is the proper way to shutdown a kthread*/
        return 0;
 }
 
@@ -1169,25 +1169,12 @@ static const struct file_operations lirc_fops = {
        .release        = close
 };
 
-/* FIXME - investigate if this is the proper way to shutdown a kthread */
 static void destroy_rx_kthread(struct IR_rx *rx)
 {
-       DECLARE_COMPLETION(tn);
-       DECLARE_COMPLETION(tn2);
-
-       if (rx == NULL)
-               return;
-
        /* end up polling thread */
-       if (rx->task && !IS_ERR(rx->task)) {
-               rx->t_notify = &tn;
-               rx->t_notify2 = &tn2;
-               rx->shutdown = 1;
-               wake_up_process(rx->task);
-               complete(&tn2);
-               wait_for_completion(&tn);
-               rx->t_notify = NULL;
-               rx->t_notify2 = NULL;
+       if (rx != NULL && !IS_ERR_OR_NULL(rx->task)) {
+               kthread_stop(rx->task);
+               rx->task = NULL;
        }
 }
 
@@ -1290,8 +1277,8 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
        else if (tx_only) /* module option */
                return -ENXIO;
 
-       zilog_info("%s: probing IR %s on %s (i2c-%d)\n",
-                  __func__, tx_probe ? "Tx" : "Rx", adap->name, adap->nr);
+       zilog_info("probing IR %s on %s (i2c-%d)\n",
+                  tx_probe ? "Tx" : "Rx", adap->name, adap->nr);
 
        mutex_lock(&ir_devices_lock);
 
@@ -1360,27 +1347,23 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
        /* Proceed only if we have the required Tx and Rx clients ready to go */
        if (ir->tx == NULL ||
            (ir->rx == NULL && !tx_only)) {
-               zilog_info("%s: probe of IR %s on %s (i2c-%d) done, waiting on "
-                          "IR %s\n", __func__, tx_probe ? "Tx" : "Rx",
-                          adap->name, adap->nr, tx_probe ? "Rx" : "Tx");
+               zilog_info("probe of IR %s on %s (i2c-%d) done. Waiting on "
+                          "IR %s.\n", tx_probe ? "Tx" : "Rx", adap->name,
+                          adap->nr, tx_probe ? "Rx" : "Tx");
                goto out_ok;
        }
 
        /* initialise RX device */
        if (ir->rx != NULL) {
-               DECLARE_COMPLETION(tn);
-
                /* try to fire up polling thread */
-               ir->rx->t_notify = &tn;
-               ir->rx->task = kthread_run(lirc_thread, ir, "lirc_zilog");
+               ir->rx->task = kthread_run(lirc_thread, ir,
+                                          "zilog-rx-i2c-%d", adap->nr);
                if (IS_ERR(ir->rx->task)) {
                        ret = PTR_ERR(ir->rx->task);
                        zilog_error("%s: could not start IR Rx polling thread"
                                    "\n", __func__);
                        goto out_free_xx;
                }
-               wait_for_completion(&tn);
-               ir->rx->t_notify = NULL;
        }
 
        /* register with lirc */
@@ -1404,6 +1387,8 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
                        goto out_unregister;
        }
 
+       zilog_info("probe of IR %s on %s (i2c-%d) done. IR unit ready.\n",
+                  tx_probe ? "Tx" : "Rx", adap->name, adap->nr);
 out_ok:
        mutex_unlock(&ir_devices_lock);
        return 0;