[media] pwc: Use one shared usb command buffer

The pwc driver used to:
1. kmalloc a buffer
2. memcpy data to send over usb there
3. do the usb_control_msg call (which does not work with data on the stack)
4. free the buffer

For every usb command send. This patch changes the code to instead malloc
a buffer for this purpose once and use it everywhere.

[mchehab@redhat.com: Fix a compilation breakage with allyesconfig:
 drivers/media/video/pwc/pwc-ctrl.c: In function ‘pwc_get_cmos_sensor’:
 drivers/media/video/pwc/pwc-ctrl.c:546:3: warning: passing argument 4 of ‘recv_control_msg’ makes integer from pointer without a cast [en$
 drivers/media/video/pwc/pwc-ctrl.c:107:12: note: expected ‘int’ but argument is of type ‘unsigned char *’
 drivers/media/video/pwc/pwc-ctrl.c:546:3: error: too many arguments to function ‘recv_control_msg’
 drivers/media/video/pwc/pwc-ctrl.c:107:12: note: declared here]

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

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/media/video/pwc/pwc-if.c b/drivers/media/video/pwc/pwc-if.c
index 23eaceea486..a07df4e4aa0 100644
--- a/drivers/media/video/pwc/pwc-if.c
+++ b/drivers/media/video/pwc/pwc-if.c
@@ -605,6 +605,7 @@ static void pwc_video_release(struct v4l2_device *v)
 
 	v4l2_ctrl_handler_free(&pdev->ctrl_handler);
 
+	kfree(pdev->ctrl_buf);
 	kfree(pdev);
 }
 
@@ -1115,6 +1116,14 @@ static int usb_pwc_probe(struct usb_interface *intf, const struct usb_device_id
 	if (hint < MAX_DEV_HINTS)
 		device_hint[hint].pdev = pdev;
 
+	/* Allocate USB command buffers */
+	pdev->ctrl_buf = kmalloc(sizeof(pdev->cmd_buf), GFP_KERNEL);
+	if (!pdev->ctrl_buf) {
+		PWC_ERROR("Oops, could not allocate memory for pwc_device.\n");
+		rc = -ENOMEM;
+		goto err_free_mem;
+	}
+
 #ifdef CONFIG_USB_PWC_DEBUG
 	/* Query sensor type */
 	if (pwc_get_cmos_sensor(pdev, &rc) >= 0) {
@@ -1199,6 +1208,7 @@ err_free_controls:
 err_free_mem:
 	if (hint < MAX_DEV_HINTS)
 		device_hint[hint].pdev = NULL;
+	kfree(pdev->ctrl_buf);
 	kfree(pdev);
 	return rc;
 }