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V4L/DVB (3672): Fix memory leak in dvr open 

The dvr device could be opened multiple times simultaneously in O_RDONLY mode.
Each open after the first would allocate a new dvr buffer (1880 KB) and leak
the old buffer.  The first close would de-allocate the dvr buffer and cause
all other open dvrs to stop working.  This patch allows only a single O_RDONLY
open of the drv device, as per the API specification.  Multiple O_WRONLY opens
are still allowed and don't appear to cause any problems.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Andrew de Quincey <adq_dvb@lidskialf.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Trent Piepho 2006-03-30 15:53:32 -03:00 committed by Mauro Carvalho Chehab
parent 2f03ee8e6b
commit 5e85bd057f
1 changed files with 9 additions and 3 deletions
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12
drivers/media/dvb/dvb-core/dmxdev.c
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@ -141,12 +141,18 @@ static int dvb_dvr_open(struct inode *inode, struct file *file)
}
if ((file->f_flags & O_ACCMODE) == O_RDONLY) {
void *mem = vmalloc(DVR_BUFFER_SIZE);
void *mem;
if (!dvbdev->readers) {
mutex_unlock(&dmxdev->mutex);
return -EBUSY;
}
mem = vmalloc(DVR_BUFFER_SIZE);
if (!mem) {
mutex_unlock(&dmxdev->mutex);
return -ENOMEM;
}
dvb_ringbuffer_init(&dmxdev->dvr_buffer, mem, DVR_BUFFER_SIZE);
dvbdev->readers--;
}
if ((file->f_flags & O_ACCMODE) == O_WRONLY) {
@ -184,6 +190,7 @@ static int dvb_dvr_release(struct inode *inode, struct file *file)
dmxdev->dvr_orig_fe);
}
if ((file->f_flags & O_ACCMODE) == O_RDONLY) {
dvbdev->readers++;
if (dmxdev->dvr_buffer.data) {
void *mem = dmxdev->dvr_buffer.data;
mb();
@ -1029,8 +1036,7 @@ static struct file_operations dvb_dvr_fops = {
static struct dvb_device dvbdev_dvr = {
.priv = NULL,
.users = 1,
.writers = 1,
.readers = 1,
.fops = &dvb_dvr_fops
};