]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
usb-serial: change logic of serial lookups
authorAlan Stern <stern@rowland.harvard.edu>
Tue, 1 Sep 2009 15:38:59 +0000 (11:38 -0400)
committerLive-CD User <linux@linux.site>
Sat, 19 Sep 2009 20:13:40 +0000 (13:13 -0700)
commit8bc2c1b2daf95029658868cb1427baea2da87139
tree9895248e23de85d55a4d4ec9234aec7e58de285b
parentf5b0953a89fa3407fb293cc54ead7d8feec489e4
usb-serial: change logic of serial lookups

This patch (as1286) changes usb_serial_get_by_index().  Now the
routine will check whether the serial device has been disconnected; if
it has then the return value will be NULL.  If the device hasn't been
disconnected then the routine will return with serial->disc_mutex
held, so that the caller can use the structure without fear of racing
against driver unloads.

This permits the scope of table_mutex in destroy_serial() to be
reduced.  Instead of protecting the entire function, it suffices to
protect the part that actually uses serial_table[], i.e., the call to
return_serial().  There's no longer any danger of the refcount being
incremented after it reaches 0 (which was the reason for having the
large scope previously), because it can't reach 0 until the serial
device has been disconnected.

Also, the patch makes serial_install() check that serial is non-NULL
before attempting to use it.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/usb/serial/usb-serial.c