diff options
author | Andy Walls <awalls@md.metrocast.net> | 2011-01-26 21:25:47 -0300 |
---|---|---|
committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2011-03-22 19:23:50 -0300 |
commit | 9b28500a59d7ee5da5adb43bcb384391cac401c4 (patch) | |
tree | 8cf3d412625919e0f707cf5fe85e837992ad84ed /drivers/staging | |
parent | 12d896e1c17978599a98510fdfaff27a4e82c0bf (diff) |
[media] lirc_zilog: Remove broken, ineffective reference counting
The set_use_inc() and set_use_dec() functions tried to lock
the underlying bridge driver device instance in memory by
changing the use count on the device's i2c_clients. This
worked for PCI devices (ivtv, cx18, bttv). It doesn't
work for hot-pluggable usb devices (pvrusb2 and hdpvr).
With usb device instances, the driver may get locked into
memory, but the unplugged hardware is gone.
The set_use_inc() set_use_dec() functions also tried to have
lirc_zilog change its own module refernce count, which is
racy and not guaranteed to work. The lirc_dev module does
actually perform proper module ref count manipulation on the
lirc_zilog module, so there is need for lirc_zilog to
attempt a buggy module get on itself anyway.
lirc_zilog also errantly called these functions on itself
in open() and close(), but lirc_dev did that already too.
So let's just gut the bodies of the set_use_*() functions,
and remove the extra calls to them from within lirc_zilog.
Proper reference counting of the struct IR, IR_rx, and IR_tx
objects -- to handle the case when the underlying
bttv, ivtv, cx18, hdpvr, or pvrusb2 bridge driver module or
device instance goes away -- will be added in subsequent
patches.
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/staging')
-rw-r--r-- | drivers/staging/lirc/lirc_zilog.c | 32 |
1 files changed, 1 insertions, 31 deletions
diff --git a/drivers/staging/lirc/lirc_zilog.c b/drivers/staging/lirc/lirc_zilog.c index 7389b77ece8c..3a912575e12d 100644 --- a/drivers/staging/lirc/lirc_zilog.c +++ b/drivers/staging/lirc/lirc_zilog.c @@ -305,34 +305,12 @@ static int lirc_thread(void *arg) static int set_use_inc(void *data) { - struct IR *ir = data; - - if (ir->l.owner == NULL || try_module_get(ir->l.owner) == 0) - return -ENODEV; - - /* lock bttv in memory while /dev/lirc is in use */ - /* - * this is completely broken code. lirc_unregister_driver() - * must be possible even when the device is open - */ - if (ir->rx != NULL) - i2c_use_client(ir->rx->c); - if (ir->tx != NULL) - i2c_use_client(ir->tx->c); - return 0; } static void set_use_dec(void *data) { - struct IR *ir = data; - - if (ir->rx) - i2c_release_client(ir->rx->c); - if (ir->tx) - i2c_release_client(ir->tx->c); - if (ir->l.owner != NULL) - module_put(ir->l.owner); + return; } /* safe read of a uint32 (always network byte order) */ @@ -1098,7 +1076,6 @@ static struct IR *find_ir_device_by_minor(unsigned int minor) static int open(struct inode *node, struct file *filep) { struct IR *ir; - int ret; unsigned int minor = MINOR(node->i_rdev); /* find our IR struct */ @@ -1112,12 +1089,6 @@ static int open(struct inode *node, struct file *filep) /* increment in use count */ mutex_lock(&ir->ir_lock); ++ir->open; - ret = set_use_inc(ir); - if (ret != 0) { - --ir->open; - mutex_unlock(&ir->ir_lock); - return ret; - } mutex_unlock(&ir->ir_lock); /* stash our IR struct */ @@ -1139,7 +1110,6 @@ static int close(struct inode *node, struct file *filep) /* decrement in use count */ mutex_lock(&ir->ir_lock); --ir->open; - set_use_dec(ir); mutex_unlock(&ir->ir_lock); return 0; |