V4L/DVB (5842): ivtv: Add locking to ensure stream setup is atomic.

Starting an MPEG and VBI capture simultaneously caused errors in
the VBI setup: this setup was done twice when it should be done
only for the first stream that is opened.
Added a mutex to prevent this from happening.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

3 files changed, 21 insertions, 11 deletions

diff --git a/drivers/media/video/ivtv/ivtv-driver.c b/drivers/media/video/ivtv/ivtv-driver.c
index 28a53c42020d..ab7c3f6d3531 100644
--- a/drivers/media/video/ivtv/ivtv-driver.c
+++ b/drivers/media/video/ivtv/ivtv-driver.c
@@ -623,6 +623,7 @@ static int __devinit ivtv_init_struct1(struct ivtv *itv)
         itv->enc_mbox.max_mbox = 2; /* the encoder has 3 mailboxes (0-2) */
         itv->dec_mbox.max_mbox = 1; /* the decoder has 2 mailboxes (0-1) */
 
+        mutex_init(&itv->serialize_lock);
         mutex_init(&itv->i2c_bus_lock);
         mutex_init(&itv->udma.lock);
 
diff --git a/drivers/media/video/ivtv/ivtv-driver.h b/drivers/media/video/ivtv/ivtv-driver.h
index 48afd4270cbf..65ebddab3fe1 100644
--- a/drivers/media/video/ivtv/ivtv-driver.h
+++ b/drivers/media/video/ivtv/ivtv-driver.h
@@ -722,6 +722,7 @@ struct ivtv {
         int search_pack_header;
 
         spinlock_t dma_reg_lock; /* lock access to DMA engine registers */
+        struct mutex serialize_lock;  /* lock used to serialize starting streams */
 
         /* User based DMA for OSD */
         struct ivtv_user_dma udma;
diff --git a/drivers/media/video/ivtv/ivtv-streams.c b/drivers/media/video/ivtv/ivtv-streams.c
index 6af88ae9295f..d538efaf61c9 100644
--- a/drivers/media/video/ivtv/ivtv-streams.c
+++ b/drivers/media/video/ivtv/ivtv-streams.c
@@ -446,6 +446,9 @@ int ivtv_start_v4l2_encode_stream(struct ivtv_stream *s)
         if (s->v4l2dev == NULL)
                 return -EINVAL;
 
+        /* Big serialization lock to ensure no two streams are started
+           simultaneously: that can give all sorts of weird results. */
+        mutex_lock(&itv->serialize_lock);
         IVTV_DEBUG_INFO("Start encoder stream %s\n", s->name);
 
         switch (s->type) {
@@ -487,6 +490,7 @@ int ivtv_start_v4l2_encode_stream(struct ivtv_stream *s)
                         0, sizeof(itv->vbi.sliced_mpeg_size));
                 break;
         default:
+                mutex_unlock(&itv->serialize_lock);
                 return -EINVAL;
         }
         s->subtype = subtype;
@@ -568,6 +572,7 @@ int ivtv_start_v4l2_encode_stream(struct ivtv_stream *s)
         if (ivtv_vapi(itv, CX2341X_ENC_START_CAPTURE, 2, captype, subtype))
         {
                 IVTV_DEBUG_WARN( "Error starting capture!\n");
+                mutex_unlock(&itv->serialize_lock);
                 return -EINVAL;
         }
 
@@ -583,6 +588,7 @@ int ivtv_start_v4l2_encode_stream(struct ivtv_stream *s)
 
         /* you're live! sit back and await interrupts :) */
         atomic_inc(&itv->capturing);
+        mutex_unlock(&itv->serialize_lock);
         return 0;
 }
 
@@ -762,17 +768,6 @@ int ivtv_stop_v4l2_encode_stream(struct ivtv_stream *s, int gop_end)
         /* when: 0 =  end of GOP  1 = NOW!, type: 0 = mpeg, subtype: 3 = video+audio */
         ivtv_vapi(itv, CX2341X_ENC_STOP_CAPTURE, 3, stopmode, cap_type, s->subtype);
 
-        /* only run these if we're shutting down the last cap */
-        if (atomic_read(&itv->capturing) - 1 == 0) {
-                /* event notification (off) */
-                if (test_and_clear_bit(IVTV_F_I_DIG_RST, &itv->i_flags)) {
-                        /* type: 0 = refresh */
-                        /* on/off: 0 = off, intr: 0x10000000, mbox_id: -1: none */
-                        ivtv_vapi(itv, CX2341X_ENC_SET_EVENT_NOTIFICATION, 4, 0, 0, IVTV_IRQ_ENC_VIM_RST, -1);
-                        ivtv_set_irq_mask(itv, IVTV_IRQ_ENC_VIM_RST);
-                }
-        }
-
         then = jiffies;
 
         if (!test_bit(IVTV_F_S_PASSTHROUGH, &s->s_flags)) {
@@ -840,17 +835,30 @@ int ivtv_stop_v4l2_encode_stream(struct ivtv_stream *s, int gop_end)
         /* Clear capture and no-read bits */
         clear_bit(IVTV_F_S_STREAMING, &s->s_flags);
 
+        /* ensure these global cleanup actions are done only once */
+        mutex_lock(&itv->serialize_lock);
+
         if (s->type == IVTV_ENC_STREAM_TYPE_VBI)
                 ivtv_set_irq_mask(itv, IVTV_IRQ_ENC_VBI_CAP);
 
         if (atomic_read(&itv->capturing) > 0) {
+                mutex_unlock(&itv->serialize_lock);
                 return 0;
         }
 
         /* Set the following Interrupt mask bits for capture */
         ivtv_set_irq_mask(itv, IVTV_IRQ_MASK_CAPTURE);
 
+        /* event notification (off) */
+        if (test_and_clear_bit(IVTV_F_I_DIG_RST, &itv->i_flags)) {
+                /* type: 0 = refresh */
+                /* on/off: 0 = off, intr: 0x10000000, mbox_id: -1: none */
+                ivtv_vapi(itv, CX2341X_ENC_SET_EVENT_NOTIFICATION, 4, 0, 0, IVTV_IRQ_ENC_VIM_RST, -1);
+                ivtv_set_irq_mask(itv, IVTV_IRQ_ENC_VIM_RST);
+        }
+
         wake_up(&s->waitq);
+        mutex_unlock(&itv->serialize_lock);
 
         return 0;
 }