Hi,
the attached patch fixes an SMP race in open and makes sure that read & write
are not called at the same time.
It compiles and I can still watch TV, but please test this.
Regards
Oliver
--- include/linux/videodev.h.alt Mon Oct 30 07:41:41 2000
+++ include/linux/videodev.h Mon Oct 30 07:41:44 2000
@@ -32,6 +32,7 @@
int busy;
int minor;
devfs_handle_t devfs_handle;
+ struct semaphore lock;
};
extern int videodev_init(void);
--- drivers/media/video/videodev.c.alt Sun Oct 29 20:42:54 2000
+++ drivers/media/video/videodev.c Mon Oct 30 07:41:48 2000
@@ -30,16 +30,17 @@
#include <asm/uaccess.h>
#include <asm/system.h>
+#include <asm/bitops.h>
#include <linux/kmod.h>
-#define VIDEO_NUM_DEVICES 256
+#define VIDEO_NUM_DEVICES 256
/*
- * Active devices
+ * Active devices
*/
-
+
static struct video_device *video_device[VIDEO_NUM_DEVICES];
@@ -78,31 +79,36 @@
static struct video_init video_init_list[]={
#ifdef CONFIG_VIDEO_BWQCAM
{"bw-qcam", init_bw_qcams},
-#endif
+#endif
#ifdef CONFIG_VIDEO_CPIA
{"cpia", cpia_init},
-#endif
+#endif
#ifdef CONFIG_VIDEO_PLANB
{"planb", init_planbs},
#endif
#ifdef CONFIG_VIDEO_ZORAN
{"zoran", init_zoran_cards},
-#endif
+#endif
{"end", NULL}
};
/*
* Read will do some smarts later on. Buffer pin etc.
*/
-
+
static ssize_t video_read(struct file *file,
char *buf, size_t count, loff_t *ppos)
{
+ ssize_t retval;
struct video_device *vfl=video_device[MINOR(file->f_dentry->d_inode->i_rdev)];
- if(vfl->read)
- return vfl->read(vfl, buf, count, file->f_flags&O_NONBLOCK);
+ if(vfl->read) {
+ down(&(vfl->lock));
+ retval = vfl->read(vfl, buf, count, file->f_flags&O_NONBLOCK);
+ up(&(vfl->lock));
+ }
else
- return -EINVAL;
+ retval = -EINVAL;
+ return retval;
}
@@ -111,14 +117,19 @@
* for some boards I guess..
*/
-static ssize_t video_write(struct file *file, const char *buf,
+static ssize_t video_write(struct file *file, const char *buf,
size_t count, loff_t *ppos)
{
+ ssize_t retval;
struct video_device *vfl=video_device[MINOR(file->f_dentry->d_inode->i_rdev)];
- if(vfl->write)
- return vfl->write(vfl, buf, count, file->f_flags&O_NONBLOCK);
+ if(vfl->write) {
+ down(&(vfl->lock));
+ retval = vfl->write(vfl, buf, count, file->f_flags&O_NONBLOCK);
+ up(&(vfl->lock));
+ }
else
- return 0;
+ retval = 0;
+ return retval;
}
/*
@@ -145,10 +156,10 @@
unsigned int minor = MINOR(inode->i_rdev);
int err;
struct video_device *vfl;
-
+
if(minor>=VIDEO_NUM_DEVICES)
return -ENODEV;
-
+
vfl=video_device[minor];
if(vfl==NULL) {
char modname[20];
@@ -159,26 +170,26 @@
if (vfl==NULL)
return -ENODEV;
}
- if(vfl->busy)
+ if(test_and_set_bit(0,&(vfl->busy)))
return -EBUSY;
- vfl->busy=1; /* In case vfl->open sleeps */
-
+
if(vfl->open)
{
err=vfl->open(vfl,0); /* Tell the device it is open */
if(err)
{
- vfl->busy=0;
+ clear_bit(0,&(vfl->busy));
return err;
}
}
+ init_MUTEX(&(vfl->lock));
return 0;
}
/*
* Last close of a video for Linux device
*/
-
+
static int video_release(struct inode *inode, struct file *file)
{
struct video_device *vfl;
@@ -186,7 +197,7 @@
vfl=video_device[MINOR(inode->i_rdev)];
if(vfl->close)
vfl->close(vfl);
- vfl->busy=0;
+ clear_bit(0,&(vfl->busy));
unlock_kernel();
return 0;
}
@@ -195,7 +206,7 @@
* Question: Should we be able to capture and then seek around the
* image ?
*/
-
+
static long long video_lseek(struct file * file,
long long offset, int origin)
{
@@ -210,26 +221,22 @@
if(err!=-ENOIOCTLCMD)
return err;
-
- switch(cmd)
- {
- default:
- return -EINVAL;
- }
+ else
+ return -EINVAL;
}
/*
* We need to do MMAP support
*/
-
-
+
+
int video_mmap(struct file *file, struct vm_area_struct *vma)
{
int ret = -EINVAL;
struct video_device *vfl=video_device[MINOR(file->f_dentry->d_inode->i_rdev)];
if(vfl->mmap) {
lock_kernel();
- ret = vfl->mmap(vfl, (char *)vma->vm_start,
+ ret = vfl->mmap(vfl, (char *)vma->vm_start,
(unsigned long)(vma->vm_end-vma->vm_start));
unlock_kernel();
}
@@ -264,7 +271,7 @@
/* Sanity check */
if (tmp == &videodev_proc_list)
goto skip;
-
+
#define PRINT_VID_TYPE(x) do { if (vfd->type & x) \
out += sprintf (out, "%c%s", c, #x); c='|';} while (0)
@@ -393,7 +400,7 @@
* @vfd: video device structure we want to register
* @type: type of device to register
* FIXME: needs a semaphore on 2.3.x
- *
+ *
* The registration code assigns minor numbers based on the type
* requested. -ENFILE is returned in all the device slots for this
* category are full. If not then the minor field is set and the
@@ -409,9 +416,9 @@
*
* %VFL_TYPE_VBI - Vertical blank data (undecoded)
*
- * %VFL_TYPE_RADIO - A radio card
+ * %VFL_TYPE_RADIO - A radio card
*/
-
+
int video_register_device(struct video_device *vfd, int type)
{
int i=0;
@@ -419,7 +426,7 @@
int err;
int end;
char *name_base;
-
+
switch(type)
{
case VFL_TYPE_GRABBER:
