linux.git/drivers/usb/serial/generic.c, branch v2.6.31

tty: Fix USB kref leak

2009-07-11T02:17:22+00:00

The sysrq code acquired a kref leak. Fix it by passing the tty separately
from the caller (thus effectively using the callers kref which all the
callers hold anyway)

Signed-off-by: Alan Cox 
Signed-off-by: Linus Torvalds

tty: Sort out the USB sysrq changes that wrecked performance

2009-07-11T02:17:22+00:00

We can't go around calling all sorts of magic per character functions at
full rate 3G data speed.

Signed-off-by: Alan Cox 
Signed-off-by: Linus Torvalds

USB: usb-serial: replace shutdown with disconnect, release

2009-06-16T04:44:47+00:00

This patch (as1254) splits up the shutdown method of usb_serial_driver
into a disconnect and a release method.

The problem is that the usb-serial core was calling shutdown during
disconnect handling, but drivers didn't expect it to be called until
after all the open file references had been closed.  The result was an
oops when the close method tried to use memory that had been
deallocated by shutdown.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

USB: usb_serial: only allow sysrq on a console port

2009-06-16T04:44:47+00:00

The only time a sysrq should get processed is if the attached device
is a console.  This is intended to protect sysrq execution on a host
connected with a terminal program.

Here is the problem scenario:

host A <-- rs232 link --> host B

Host A is using mincom and a usb pl2303 device to connect to host b
which is a linux system with a usb pl2303 device acting as the serial
console.  When host B is rebooted the pl2303 emits random junk
characters on reset.  These character sequences contain serial break
signals most of the time and when translated to a sysrq have caused
host A to get random processes killed, reboots or power down.

It is true that in this setup with this patch host B might still have
the same problem as host A if you reboot host A.  In most cases host A
is a development host which seldom gets rebooted, and you could turn
off sysrq temporarily on host B if you need to reboot host A.

Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

USB: serial: usb_debug,usb_generic_serial: implement sysrq and serial break

2009-06-16T04:44:45+00:00

The usb_debug driver was modified to implement serial break handling
by using a "magic" data packet comprised of the sequence:

       0x00 0xff 0x01 0xfe   0x00 0xfe 0x01 0xff

When the tty layer requests a serial break the usb_debug driver sends
the magic packet.  On the receiving side the magic packet is thrown
away or a sysrq is activated depending on what kernel .config options
have been set.

The generic serial driver was modified as well as the usb serial
headers to generically implement sysrq processing in the same way the
non usb uart based drivers implement the sysrq handling.  This will
allow other usb serial devices to implement sysrq handling as desired.

The new usb serial functions are named similarly and implemented
similarly to the uart functions as follows:

usb_serial_handle_break <-> uart_handle_break
usb_serial_handle_sysrq_char <-> uart_handle_sysrq_char

Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

USB: usb_debug, usb_generic_serial: implement multi urb write

2009-06-16T04:44:45+00:00

The usb_debug driver, when used as the console, will always fail to
insert the carriage return and new line sequence as well as randomly
drop console output.  This is a result of only having the single
write_urb and that the tty layer will have a lock that prevents the
processing of the back to back urb requests.

The solution is to allow more than one urb to be outstanding and have
a slightly deeper transmit queue.  The idea and some code is borrowed
from the ftdi_sio usb driver.

The generic usb serial driver was modified so as to allow the classic
method of 1 write urb, or a multi write urb scheme with N allowed
outstanding urbs where N is controlled by max_in_flight_urbs.  When
max_in_flight_urbs in a "struct usb_serial_driver" is non zero the
multi write urb scheme will be used.

The size of 4000 was selected for the usb_debug driver so that the
driver lowers possibility of losing the queued console messages during
the kernel startup.

Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

tty: Bring the usb tty port structure into more use

2009-06-11T15:50:56+00:00

This allows us to clean stuff up, but is probably also going to cause
some app breakage with buggy apps as we now implement proper POSIX behaviour
for USB ports matching all the other ports. This does also mean other apps
that break on USB will now work properly.

Signed-off-by: Alan Cox 
Signed-off-by: Linus Torvalds

USB: removal of tty->low_latency hack dating back to the old serial code

2009-04-23T21:15:29+00:00

This removes tty->low_latency from all USB serial drivers that push
data into the tty layer at hard interrupt context. It's no longer needed
and actually harmful.

Signed-off-by: Oliver Neukum 
Cc: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

USB: serial: export symbol of usb_serial_generic_resume

2009-03-24T23:20:29+00:00

This exports a symbol for usb_serial_generic_resume, so that modules can
use it.

Signed-off-by: Oliver Neukum 
Signed-off-by: Greg Kroah-Hartman

USB: serial generic resume function fix

2009-03-24T23:20:29+00:00

This removes an unnecessary check for autoresume from the generic
resume method. The check has been obsoleted by the now delayed
increase of the usage counter which makes the error this check prevented
impossible. This change allows drivers which only use the bulk read URB
the use of the generic method even if they support autosuspend.

Signed-off-by: Oliver Neukum 
Signed-off-by: Greg Kroah-Hartman