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authorPete Zaitcev2008-03-04 23:28:42 -0800
committerGreg Kroah-Hartman2008-03-10 16:42:25 -0700
commitb507cc9710d8b6e3013468b40522e235342fc84a (patch)
tree9543c5e06c1d1fb6890d2520b876bf9828c367a6 /drivers/usb/serial
parentcdeeeae056a429e729ae9e914fa8142ee45bee93 (diff)
USB: fix usb-serial generic recursive lock
Nobody should be using the generic usb-serial for anything other than testing. Still, it's not a good thing that it's easy to lock up. There is a traceback from NMI oopser here: https://bugzilla.redhat.com/show_bug.cgi?id=431379 But in short, if a line discipline has a chance to echo anything, input can loop back a write method. So, don't call tty_flip_buffer_push from under a lock taken on write path. Signed-off-by: Pete Zaitcev <zaitcev@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/serial')
-rw-r--r--drivers/usb/serial/generic.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 97fa3c428435..7cfce9dabb90 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -323,7 +323,7 @@ static void flush_and_resubmit_read_urb (struct usb_serial_port *port)
room = tty_buffer_request_room(tty, urb->actual_length);
if (room) {
tty_insert_flip_string(tty, urb->transfer_buffer, room);
- tty_flip_buffer_push(tty); /* is this allowed from an URB callback ? */
+ tty_flip_buffer_push(tty);
}
}
@@ -349,10 +349,12 @@ void usb_serial_generic_read_bulk_callback (struct urb *urb)
/* Throttle the device if requested by tty */
spin_lock_irqsave(&port->lock, flags);
- if (!(port->throttled = port->throttle_req))
- /* Handle data and continue reading from device */
+ if (!(port->throttled = port->throttle_req)) {
+ spin_unlock_irqrestore(&port->lock, flags);
flush_and_resubmit_read_urb(port);
- spin_unlock_irqrestore(&port->lock, flags);
+ } else {
+ spin_unlock_irqrestore(&port->lock, flags);
+ }
}
EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback);