[media] gspca: Don't set gspca_dev->dev to NULL before stop0

In commit a3d6e8cc0e6ddc8b3cfdeb3c979f07ed1aa528b3 gspca_dev->dev is set
to NULL on disconnect, before calling stop0. The plan was to get rid of
gspca_dev->present and instead simply check for gspca_dev->dev everywhere
where we were checking for present. This should be race free since all users
of gspca_dev->dev hold the usb_lock, or so I thought.

But I was wrong, drivers which use a work-queue + synchronous bulk transfers
to get the video data don't hold the usb_lock while doing so, their stop0
callbacks stop the workqueue, so they won't be using gspca_dev->dev anymore
after the stop0 call, but they might be dereferincing it before, so we should
not set gspca_dev->dev to NULL on disconnect before calling stop0.

This also means that the workqueue functions in these drivers cannot
use gspca_dev->dev to check if they need to stop because of disconnection,
so we will need to keep gspca_dev->present around, and set that to 0 on
disconnect, before calling stop0. Unfortunately as part of the plan to remove
gspca_dev->present, these workqueues where already moved over to checking
for gspca_dev->dev instead of gspca_dev->present as part of commit
254902b01d2acc6aced99ec17caa4c6cd890cdea, so this patch also reverts those
parts of that commit.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

8 files changed, 19 insertions, 22 deletions

diff --git a/drivers/media/usb/gspca/finepix.c b/drivers/media/usb/gspca/finepix.c
index c8f2201cc35..04807eee777 100644
--- a/drivers/media/usb/gspca/finepix.c
+++ b/drivers/media/usb/gspca/finepix.c
@@ -94,7 +94,7 @@ static void dostream(struct work_struct *work)
 
         /* loop reading a frame */
 again:
-        while (gspca_dev->dev && gspca_dev->streaming) {
+        while (gspca_dev->present && gspca_dev->streaming) {
 #ifdef CONFIG_PM
                 if (gspca_dev->frozen)
                         break;
@@ -110,7 +110,7 @@ again:
                 if (gspca_dev->frozen)
                         break;
 #endif
-                if (!gspca_dev->dev || !gspca_dev->streaming)
+                if (!gspca_dev->present || !gspca_dev->streaming)
                         break;
 
                 /* the frame comes in parts */
@@ -129,7 +129,7 @@ again:
                         if (gspca_dev->frozen)
                                 goto out;
 #endif
-                        if (!gspca_dev->dev || !gspca_dev->streaming)
+                        if (!gspca_dev->present || !gspca_dev->streaming)
                                 goto out;
                         if (len < FPIX_MAX_TRANSFER ||
                                 (data[len - 2] == 0xff &&
diff --git a/drivers/media/usb/gspca/gspca.c b/drivers/media/usb/gspca/gspca.c
index d4e8343f5b1..7cce0f201d7 100644
--- a/drivers/media/usb/gspca/gspca.c
+++ b/drivers/media/usb/gspca/gspca.c
@@ -2358,8 +2358,6 @@ void gspca_disconnect(struct usb_interface *intf)
 
         mutex_lock(&gspca_dev->usb_lock);
 
-        usb_set_intfdata(intf, NULL);
-        gspca_dev->dev = NULL;
         gspca_dev->present = 0;
         destroy_urbs(gspca_dev);
 
@@ -2375,6 +2373,7 @@ void gspca_disconnect(struct usb_interface *intf)
         if (gspca_dev->sd_desc->stop0 && gspca_dev->streaming)
                 gspca_dev->sd_desc->stop0(gspca_dev);
         gspca_dev->streaming = 0;
+        gspca_dev->dev = NULL;
         wake_up_interruptible(&gspca_dev->wq);
 
         v4l2_device_disconnect(&gspca_dev->v4l2_dev);
diff --git a/drivers/media/usb/gspca/jl2005bcd.c b/drivers/media/usb/gspca/jl2005bcd.c
index 234777116e5..c4b4a9598db 100644
--- a/drivers/media/usb/gspca/jl2005bcd.c
+++ b/drivers/media/usb/gspca/jl2005bcd.c
@@ -335,7 +335,7 @@ static void jl2005c_dostream(struct work_struct *work)
                 goto quit_stream;
         }
 
-        while (gspca_dev->dev && gspca_dev->streaming) {
+        while (gspca_dev->present && gspca_dev->streaming) {
 #ifdef CONFIG_PM
                 if (gspca_dev->frozen)
                         break;
@@ -371,7 +371,7 @@ static void jl2005c_dostream(struct work_struct *work)
                                         buffer, act_len);
                         header_read = 1;
                 }
-                while (bytes_left > 0 && gspca_dev->dev) {
+                while (bytes_left > 0 && gspca_dev->present) {
                         data_len = bytes_left > JL2005C_MAX_TRANSFER ?
                                 JL2005C_MAX_TRANSFER : bytes_left;
                         ret = usb_bulk_msg(gspca_dev->dev,
@@ -394,7 +394,7 @@ static void jl2005c_dostream(struct work_struct *work)
                 }
         }
 quit_stream:
-        if (gspca_dev->dev) {
+        if (gspca_dev->present) {
                 mutex_lock(&gspca_dev->usb_lock);
                 jl2005c_stop(gspca_dev);
                 mutex_unlock(&gspca_dev->usb_lock);
diff --git a/drivers/media/usb/gspca/sq905.c b/drivers/media/usb/gspca/sq905.c
index a8ac97931ad..2e05acab304 100644
--- a/drivers/media/usb/gspca/sq905.c
+++ b/drivers/media/usb/gspca/sq905.c
@@ -232,7 +232,7 @@ static void sq905_dostream(struct work_struct *work)
         frame_sz = gspca_dev->cam.cam_mode[gspca_dev->curr_mode].sizeimage
                         + FRAME_HEADER_LEN;
 
-        while (gspca_dev->dev && gspca_dev->streaming) {
+        while (gspca_dev->present && gspca_dev->streaming) {
 #ifdef CONFIG_PM
                 if (gspca_dev->frozen)
                         break;
@@ -246,7 +246,7 @@ static void sq905_dostream(struct work_struct *work)
                    we must finish reading an entire frame, otherwise the
                    next time we stream we start reading in the middle of a
                    frame. */
-                while (bytes_left > 0 && gspca_dev->dev) {
+                while (bytes_left > 0 && gspca_dev->present) {
                         data_len = bytes_left > SQ905_MAX_TRANSFER ?
                                 SQ905_MAX_TRANSFER : bytes_left;
                         ret = sq905_read_data(gspca_dev, buffer, data_len, 1);
@@ -278,7 +278,7 @@ static void sq905_dostream(struct work_struct *work)
                                 gspca_frame_add(gspca_dev, LAST_PACKET,
                                                 NULL, 0);
                 }
-                if (gspca_dev->dev) {
+                if (gspca_dev->present) {
                         /* acknowledge the frame */
                         mutex_lock(&gspca_dev->usb_lock);
                         ret = sq905_ack_frame(gspca_dev);
@@ -288,7 +288,7 @@ static void sq905_dostream(struct work_struct *work)
                 }
         }
 quit_stream:
-        if (gspca_dev->dev) {
+        if (gspca_dev->present) {
                 mutex_lock(&gspca_dev->usb_lock);
                 sq905_command(gspca_dev, SQ905_CLEAR);
                 mutex_unlock(&gspca_dev->usb_lock);
diff --git a/drivers/media/usb/gspca/sq905c.c b/drivers/media/usb/gspca/sq905c.c
index 70fae6982e9..784620c102b 100644
--- a/drivers/media/usb/gspca/sq905c.c
+++ b/drivers/media/usb/gspca/sq905c.c
@@ -150,7 +150,7 @@ static void sq905c_dostream(struct work_struct *work)
                 goto quit_stream;
         }
 
-        while (gspca_dev->dev && gspca_dev->streaming) {
+        while (gspca_dev->present && gspca_dev->streaming) {
 #ifdef CONFIG_PM
                 if (gspca_dev->frozen)
                         break;
@@ -173,7 +173,7 @@ static void sq905c_dostream(struct work_struct *work)
                 packet_type = FIRST_PACKET;
                 gspca_frame_add(gspca_dev, packet_type,
                                 buffer, FRAME_HEADER_LEN);
-                while (bytes_left > 0 && gspca_dev->dev) {
+                while (bytes_left > 0 && gspca_dev->present) {
                         data_len = bytes_left > SQ905C_MAX_TRANSFER ?
                                 SQ905C_MAX_TRANSFER : bytes_left;
                         ret = usb_bulk_msg(gspca_dev->dev,
@@ -195,7 +195,7 @@ static void sq905c_dostream(struct work_struct *work)
                 }
         }
 quit_stream:
-        if (gspca_dev->dev) {
+        if (gspca_dev->present) {
                 mutex_lock(&gspca_dev->usb_lock);
                 sq905c_command(gspca_dev, SQ905C_CLEAR, 0);
                 mutex_unlock(&gspca_dev->usb_lock);
diff --git a/drivers/media/usb/gspca/vicam.c b/drivers/media/usb/gspca/vicam.c
index b1a64b91266..57d88f70c39 100644
--- a/drivers/media/usb/gspca/vicam.c
+++ b/drivers/media/usb/gspca/vicam.c
@@ -194,7 +194,7 @@ static void vicam_dostream(struct work_struct *work)
                 goto exit;
         }
 
-        while (gspca_dev->dev && gspca_dev->streaming) {
+        while (gspca_dev->present && gspca_dev->streaming) {
 #ifdef CONFIG_PM
                 if (gspca_dev->frozen)
                         break;
@@ -299,7 +299,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
         dev->work_thread = NULL;
         mutex_lock(&gspca_dev->usb_lock);
 
-        if (gspca_dev->dev)
+        if (gspca_dev->present)
                 vicam_set_camera_power(gspca_dev, 0);
 }
 
diff --git a/drivers/media/usb/gspca/xirlink_cit.c b/drivers/media/usb/gspca/xirlink_cit.c
index 13b8d395d21..d4b23c9bf90 100644
--- a/drivers/media/usb/gspca/xirlink_cit.c
+++ b/drivers/media/usb/gspca/xirlink_cit.c
@@ -2697,9 +2697,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
 {
         struct sd *sd = (struct sd *) gspca_dev;
 
-        /* We cannot use gspca_dev->present here as that is not set when
-           sd_init gets called and we get called from sd_init */
-        if (!gspca_dev->dev)
+        if (!gspca_dev->present)
                 return;
 
         switch (sd->model) {
diff --git a/drivers/media/usb/gspca/zc3xx.c b/drivers/media/usb/gspca/zc3xx.c
index f0bacee33ef..234d9eaa8ee 100644
--- a/drivers/media/usb/gspca/zc3xx.c
+++ b/drivers/media/usb/gspca/zc3xx.c
@@ -5950,7 +5950,7 @@ static void transfer_update(struct work_struct *work)
                 if (gspca_dev->frozen)
                         goto err;
 #endif
-                if (!gspca_dev->dev || !gspca_dev->streaming)
+                if (!gspca_dev->present || !gspca_dev->streaming)
                         goto err;
 
                 /* Bit 0 of register 11 indicates FIFO overflow */
@@ -6842,7 +6842,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
                 mutex_lock(&gspca_dev->usb_lock);
                 sd->work_thread = NULL;
         }
-        if (!gspca_dev->dev)
+        if (!gspca_dev->present)
                 return;
         send_unknown(gspca_dev, sd->sensor);
 }