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char: lp: properly count the lp devices

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When the parallel port is usb based and the lp attaches to it based on
LP_PARPORT_AUTO, we do get /dev/lp0 and when we remove the usb device
/dev/lp0 is unregistered. If we now reconnect the usb device we get
our /dev/lp0 back. But if we now disconnect and reconnect eight times
we donot get any lp device and dmesg shows:

    lp: ignoring parallel port (max. 8)

Decrement the lp_count when the device detaches as this represents the
number of lp devices connected to the system.

Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sudip Mukherjee 2018-12-07 14:27:33 +00:00 committed by Greg Kroah-Hartman
parent dc34da4286
commit e379c1a460
1 changed files with 1 additions and 0 deletions
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drivers/char/lp.c
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@ -993,6 +993,7 @@ static void lp_detach(struct parport *port)
for (n = 0; n < LP_NO; n++) {
if (port_num[n] == port->number) {
port_num[n] = -1;
lp_count--;
device_destroy(lp_class, MKDEV(LP_MAJOR, n));
parport_unregister_device(lp_table[n].dev);
}