linux/drivers/usb
Francesco Lavra 051522bb47 USB: cdc_acm: Fix memory leak after hangup
Am Donnerstag, 10. September 2009 15:43:53 schrieb Dietmar Hilbrich:
> Hello,
>
> i have the following problem with the cdc-acm - driver:
>
> I'm using the driver with an "Ericsson F3507G" on a Thinkpad T400.
>
> If a disable the device (with the RFKill-Switch) while it is used by a
> programm like ppp, the driver doesn't seem to correctly clean up the tty,
> even after the program has been closed)
>
> The tty is still active (e.g. there still exists an entry in
> /sys/dev/char/166:0 if ttyACM0 was used) and if a reacticate the device,
> this device entry will be skipped and the Device-Nodes ttyACM1, ttyACM2
> and ttyACM3 will be used.
>
> This problem was introduced with the commit
> 10077d4a66 (before 2.6.31-rc1) and still
> exists in 2.6.31.
>
> I was able the fix this problem with the following patch:
>
> diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
> index 2bfc41e..0970d2f 100644
> --- a/drivers/usb/class/cdc-acm.c
> +++ b/drivers/usb/class/cdc-acm.c
> @@ -676,6 +676,7 @@ static void acm_tty_hangup(struct tty_struct *tty)
>         struct acm *acm = tty->driver_data;
>         tty_port_hangup(&acm->port);
>         acm_port_down(acm, 0);
> +       acm_tty_unregister(acm);
>  }

I have the same problem with cdc-acm (I'm using a Samsung SGH-U900): when I
unplug it from the USB port during a PPP connection, the ppp daemon gets the
hangup correctly (and closes the device), but the struct acm corresponding to
the device disconnected is not freed. Hence reconnecting the device results in
creation of /dev/ttyACM(x+1). The same happens when the system is hibernated
during a PPP connection.

This memory leak is due to the fact that when the tty is hung up,
tty_port_close_start() returns always zero, and acm_tty_close() never reaches
the point where acm_tty_unregister() is called.

Here is a fix for this.

Signed-off-by: Francesco Lavra <francescolavra@interfree.it>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-11-17 16:46:33 -08:00
..
atm firmware: atm/ueagle-atm: prepare for FIRMWARE_NAME_MAX removal 2009-06-15 21:30:24 -07:00
c67x00 usb/c67x00 endianness annotations 2008-06-04 08:06:01 -07:00
class USB: cdc_acm: Fix memory leak after hangup 2009-11-17 16:46:33 -08:00
core USB: Add hub descriptor update hook for xHCI 2009-09-23 06:46:40 -07:00
early USB: ehci-dbgp: errata for EHCI debug/host controller synchronization 2009-09-23 06:46:38 -07:00
gadget USB: fsl_udc_core: Fix kernel oops on module removal 2009-10-30 14:57:33 -07:00
host USB: ohci: quirk AMD prefetch for USB 1.1 ISO transfer 2009-11-17 16:46:33 -08:00
image USB: remove unneeded printks from microtek driver 2009-09-23 06:46:34 -07:00
misc USB: usblcd, fix memory leak 2009-10-09 13:52:06 -07:00
mon const: mark struct vm_struct_operations 2009-09-27 11:39:25 -07:00
musb USB: musb: invert arch depend string 2009-10-12 14:36:28 -07:00
otg USB: OMAP: ISP1301: Compile fix 2009-09-23 06:46:37 -07:00
serial USB: option: TLAYTECH TUE800 support 2009-10-30 14:57:33 -07:00
storage usb-storage: Workaround devices with bogus sense size 2009-10-14 14:54:44 -07:00
wusbcore USB: wusb: don't use the stack to read security descriptor 2009-10-14 14:54:42 -07:00
Kconfig Merge branch 'for-linus' of git://git.monstr.eu/linux-2.6-microblaze 2009-09-24 09:01:44 -07:00
Makefile USB: ehci,dbgp,early_printk: split ehci debug driver from early_printk.c 2009-09-23 06:46:38 -07:00
README USB: fix directory references in usb/README 2007-11-28 13:58:34 -08:00
usb-skeleton.c USB: skeleton: fix coding style issues. 2009-09-23 06:46:40 -07:00

README

To understand all the Linux-USB framework, you'll use these resources:

    * This source code.  This is necessarily an evolving work, and
      includes kerneldoc that should help you get a current overview.
      ("make pdfdocs", and then look at "usb.pdf" for host side and
      "gadget.pdf" for peripheral side.)  Also, Documentation/usb has
      more information.

    * The USB 2.0 specification (from www.usb.org), with supplements
      such as those for USB OTG and the various device classes.
      The USB specification has a good overview chapter, and USB
      peripherals conform to the widely known "Chapter 9".

    * Chip specifications for USB controllers.  Examples include
      host controllers (on PCs, servers, and more); peripheral
      controllers (in devices with Linux firmware, like printers or
      cell phones); and hard-wired peripherals like Ethernet adapters.

    * Specifications for other protocols implemented by USB peripheral
      functions.  Some are vendor-specific; others are vendor-neutral
      but just standardized outside of the www.usb.org team.

Here is a list of what each subdirectory here is, and what is contained in
them.

core/		- This is for the core USB host code, including the
		  usbfs files and the hub class driver ("khubd").

host/		- This is for USB host controller drivers.  This
		  includes UHCI, OHCI, EHCI, and others that might
		  be used with more specialized "embedded" systems.

gadget/		- This is for USB peripheral controller drivers and
		  the various gadget drivers which talk to them.


Individual USB driver directories.  A new driver should be added to the
first subdirectory in the list below that it fits into.

image/		- This is for still image drivers, like scanners or
		  digital cameras.
../input/	- This is for any driver that uses the input subsystem,
		  like keyboard, mice, touchscreens, tablets, etc.
../media/	- This is for multimedia drivers, like video cameras,
		  radios, and any other drivers that talk to the v4l
		  subsystem.
../net/		- This is for network drivers.
serial/		- This is for USB to serial drivers.
storage/	- This is for USB mass-storage drivers.
class/		- This is for all USB device drivers that do not fit
		  into any of the above categories, and work for a range
		  of USB Class specified devices. 
misc/		- This is for all USB device drivers that do not fit
		  into any of the above categories.