V4L/DVB: dvb: fix smscore_getbuffer() logic

Drivers shouldn't sleep while holding a spinlock. A previous workaround
were to release the spinlock before callinc schedule().

This patch uses a different approach: it just waits for the
siano hardware to answer.

Signed-off-by: Richard Zidlicky <rz@linux-m68k.org>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 12 insertions, 19 deletions

diff --git a/drivers/media/dvb/siano/smscoreapi.c b/drivers/media/dvb/siano/smscoreapi.c
index d93468cd3a85..ff3b0fa901b3 100644
--- a/drivers/media/dvb/siano/smscoreapi.c
+++ b/drivers/media/dvb/siano/smscoreapi.c
@@ -1098,33 +1098,26 @@ EXPORT_SYMBOL_GPL(smscore_onresponse);
  *
  * @return pointer to descriptor on success, NULL on error.
  */
-struct smscore_buffer_t *smscore_getbuffer(struct smscore_device_t *coredev)
+
+struct smscore_buffer_t *get_entry(struct smscore_device_t *coredev)
 {
         struct smscore_buffer_t *cb = NULL;
         unsigned long flags;
 
-        DEFINE_WAIT(wait);
-
         spin_lock_irqsave(&coredev->bufferslock, flags);
-
-        /* This function must return a valid buffer, since the buffer list is
-         * finite, we check that there is an available buffer, if not, we wait
-         * until such buffer become available.
-         */
-
-        prepare_to_wait(&coredev->buffer_mng_waitq, &wait, TASK_INTERRUPTIBLE);
-        if (list_empty(&coredev->buffers)) {
-                spin_unlock_irqrestore(&coredev->bufferslock, flags);
-                schedule();
-                spin_lock_irqsave(&coredev->bufferslock, flags);
+        if (!list_empty(&coredev->buffers)) {
+                cb = (struct smscore_buffer_t *) coredev->buffers.next;
+                list_del(&cb->entry);
         }
+        spin_unlock_irqrestore(&coredev->bufferslock, flags);
+        return cb;
+}
 
-        finish_wait(&coredev->buffer_mng_waitq, &wait);
-
-        cb = (struct smscore_buffer_t *) coredev->buffers.next;
-        list_del(&cb->entry);
+struct smscore_buffer_t *smscore_getbuffer(struct smscore_device_t *coredev)
+{
+        struct smscore_buffer_t *cb = NULL;
 
-        spin_unlock_irqrestore(&coredev->bufferslock, flags);
+        wait_event(coredev->buffer_mng_waitq, (cb = get_entry(coredev)));
 
         return cb;
 }