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 <[email protected]> --- 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 7389b77..3a91257 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; -- 1.7.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
