Reimplement fifo-based writes in the generic driver using a multiple
pre-allocated urb scheme.
In contrast to multi-urb writes, no allocations (of urbs or buffers) are
made during run-time and there is less pressure on the host stack
queues as currently only two urbs are used (implementation is generic
and can handle more than two urbs as well, though).
Initial tests using ftdi_sio show that the implementation achieves the
same (maximum) throughput at high baudrates as multi-urb writes. The CPU
usage is much lower than for multi-urb writes for small write requests
and only slightly higher for large (e.g. 2k) requests (due to extra copy
via fifo?).
Also outperforms multi-urb writes for small write requests on an
embedded arm-9 system, where multi-urb writes are CPU-bound at high
baudrates (perf reveals that a lot of time is spent in the host stack
enqueue function -- could perhaps be a bug as well).
Keeping the original write_urb, buffer and flag for now as there are
other drivers depending on them.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Generalise write buffer preparation.
This allows for drivers to manipulate (e.g. add headers) to bulk out
data before it is sent.
This adds a new function pointer to usb_serial_driver:
int (*prepare_write_buffer)(struct usb_serial_port *port,
void **dest, size_t size, const void *src, size_t count);
The function is generic and can be used with either kfifo-based or
multi-urb writes:
If *dest is NULL the implementation should allocate dest.
If src is NULL the implementation should use the port write fifo.
If not set, a generic implementation is used which simply uses memcpy or
kfifo_out.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Add process_read_urb to usb_serial_driver so that a driver can rely on
the generic read (and throttle) mechanism but still do device specific
processing of incoming data (such as adding tty_flags before pushing to
line discipline).
The default generic implementation handles sysrq for consoles but
otherwise simply pushes to tty.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Allow drivers to define custom bulk in/out buffer sizes in struct
usb_serial_driver. If not set, fall back to the default buffer size
which matches the endpoint size.
Three drivers are currently freeing the pre-allocated buffers and
allocating larger ones to achieve this at port probe (ftdi_sio) or even
at port open (ipaq and iuu_phoenix), which needless to say is suboptimal.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Replace all instances of using the console variable in struct
usb_serial_port with the struct tty_port version.
CC: Alan Cox <alan@linux.intel.com>
CC: Alan Stern <stern@rowland.harvard.edu>
CC: Oliver Neukum <oliver@neukum.org>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: linux-usb@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
We are now refcounted and all the port.count checking is no longer valid
and in fact produces false warnings.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The USB serial code was a new user of the kfifo API, and it was missed
when porting things to the new kfifo API.
Please make the write_fifo in place. Here is my patch to fix the
regression and full ported version.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Reported-and-tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the pointer to the spinlock out of struct kfifo. Most users in
tree do not actually use a spinlock, so the few exceptions now have to
call kfifo_{get,put}_locked, which takes an extra argument to a
spinlock.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a new generic kernel FIFO implementation.
The current kernel fifo API is not very widely used, because it has to
many constrains. Only 17 files in the current 2.6.31-rc5 used it.
FIFO's are like list's a very basic thing and a kfifo API which handles
the most use case would save a lot of development time and memory
resources.
I think this are the reasons why kfifo is not in use:
- The API is to simple, important functions are missing
- A fifo can be only allocated dynamically
- There is a requirement of a spinlock whether you need it or not
- There is no support for data records inside a fifo
So I decided to extend the kfifo in a more generic way without blowing up
the API to much. The new API has the following benefits:
- Generic usage: For kernel internal use and/or device driver.
- Provide an API for the most use case.
- Slim API: The whole API provides 25 functions.
- Linux style habit.
- DECLARE_KFIFO, DEFINE_KFIFO and INIT_KFIFO Macros
- Direct copy_to_user from the fifo and copy_from_user into the fifo.
- The kfifo itself is an in place member of the using data structure, this save an
indirection access and does not waste the kernel allocator.
- Lockless access: if only one reader and one writer is active on the fifo,
which is the common use case, no additional locking is necessary.
- Remove spinlock - give the user the freedom of choice what kind of locking to use if
one is required.
- Ability to handle records. Three type of records are supported:
- Variable length records between 0-255 bytes, with a record size
field of 1 bytes.
- Variable length records between 0-65535 bytes, with a record size
field of 2 bytes.
- Fixed size records, which no record size field.
- Preserve memory resource.
- Performance!
- Easy to use!
This patch:
Since most users want to have the kfifo as part of another object,
reorganize the code to allow including struct kfifo in another data
structure. This requires changing the kfifo_alloc and kfifo_init
prototypes so that we pass an existing kfifo pointer into them. This
patch changes the implementation and all existing users.
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The tty port has a port mutex used for all the port related locking so we
don't need the one in the USB serial layer any more.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
As Alan Stern pointed out - now we have tty_port_open the shutdown method
and locking allow us to whack the other bits into the full helper methods
and provide a shutdown op which the tty port code will synchronize with
setup for us.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
For the moment this just moves the USB logic over and fixes the 'what if
we open and hangup at the same time' race noticed by Oliver Neukum.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
usb:usbserial: fix flags in error case of suspension
suspended flag must be reset in error case
Signed-off-by: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1295) fixes a recently-added bug in the USB serial core.
If certain kinds of errors occur during probing, the core may call a
serial driver's release method without previously calling the attach
method. This causes some drivers (io_ti in particular) to perform an
invalid memory access.
The patch adds a new flag to keep track of whether or not attach has
been called.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
CC: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The following commit made console open fails while booting:
commit b50989dc44
Author: Alan Cox <alan@linux.intel.com>
Date: Sat Sep 19 13:13:22 2009 -0700
tty: make the kref destructor occur asynchronously
Due to tty release routines run in a workqueue now, error like the
following will be reported while booting:
INIT open /dev/console Input/output error
It also causes hibernation regression to appear as reported at
http://bugzilla.kernel.org/show_bug.cgi?id=14229
The reason is that now there's latency issue with closing, but when
we open a "closing not finished" tty, -EIO will be returned.
Fix it as per the following Alan's suggestion:
Fun but it's actually not a bug and the fix is wrong in itself as
the port may be closing but not yet being destructed, in which case
it seems to do the wrong thing. Opening a tty that is closing (and
could be closing for long periods) is supposed to return -EIO.
I suspect a better way to deal with this and keep the old console
timing is to split tty->shutdown into two functions.
tty->shutdown() - called synchronously just before we dump the tty
onto the waitqueue for destruction
tty->cleanup() - called when the destructor runs.
We would then do the shutdown part which can occur in IRQ context
fine, before queueing the rest of the release (from tty->magic = 0
... the end) to occur asynchronously
The USB update in -next would then need a call like
if (tty->cleanup)
tty->cleanup(tty);
at the top of the async function and the USB shutdown to be split
between shutdown and cleanup as the USB resource cleanup and final
tidy cannot occur synchronously as it needs to sleep.
In other words the logic becomes
final kref put
make object unfindable
async
clean it up
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
[ rjw: Rebased on top of 2.6.31-git, reworked the changelog. ]
Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl>
[ Changed serial naming to match new rules, dropped tty_shutdown as per
comments from Alan Stern - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When do_output_char() attempts to write a carriage return/line feed sequence,
it first checks to see how much buffer room is available. If there are at least
two characters free, it will write the carriage return/line feed with two calls
to tty_put_char(). It calls the tty_operation functions write() for devices that
don't support the tty_operations function put_char(). If the USB generic serial
device's write URB is not in use, it will return the buffer size when asked how
much room is available. The write() of the carriage return will cause it to mark
the write URB busy, so the subsequent write() of the line feed will be ignored.
This patch uses the kfifo infrastructure to implement a write FIFO that
accurately returns the amount of space available in the buffer.
Signed-off-by: David VomLehn <dvomlehn@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
if a subdriver has an additional suspend method, it must be called
first to allow the subdriver to return -EBUSY, because the second
half cannot be easily undone.
Signed-off-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
There are some unused variables in serial_do_down. Remove them.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1291) removes a bunch of code from serial_open(), things
that were rendered unnecessary by earlier patches. A missing spinlock
is added to protect port->port.count, which needs to be incremented
even if the open fails but not if the tty has gotten a hangup. The
test for whether the hardware has been initialized, based on the use
count, is replaced by a more transparent test of the
ASYNCB_INITIALIZED bit in the port flags.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1290) adds some missing tests. serial_down() isn't
supposed to do anything if the hardware hasn't been initialized, and
serial_close() isn't supposed to do anything if the tty has gotten a
hangup (because serial_hangup() takes care of shutting down the
hardware).
The patch also updates and adds a few debugging lines.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1289) renames serial_do_down() to serial_down() and
serial_do_free() to serial_release(). It also adds a missing call to
tty_shutdown() in serial_release().
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1288) fixes the initialization logic in
serial_install(). A new tty always needs to have a termios
initialized no matter what, not just in the case where the lower
driver will override the termios settings.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1287) makes serial_install() be reponsible for acquiring
references to the usb_serial structure and the driver module when a
tty is first used. This is more sensible than having serial_open() do
it, because a tty can be opened many times whereas it is installed
only once, when it is created. (Not to mention that these actions are
reversed when the tty is released, not when it is closed.) Finally,
it is at install time that the TTY core takes its own reference to the
usb_serial module, so it is only fitting that we should act the same
way in regard to the lower-level serial driver.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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>
This patch (as1285) rearranges the subroutines in usb-serial.c
concerned with tty lifetimes into a more logical order: install, open,
hangup, close, release. It also updates the formatting of the
kerneldoc comments.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1284) changes the referencing of the usb_serial and
usb_serial_port structures in usb-serial.c. It's not feasible to make
the port structures keep a reference to the serial structure, because
the ports need to remain in existence when serial is released -- quite
a few of the drivers expect this. Consequently taking a reference
to the port when the device file is open is insufficient; such a
reference would not pin serial.
To fix this, we now take a reference to serial when the device file is
opened. The final put_device() for the ports occurs in
destroy_serial(), so that the ports will last as long as they are
needed.
The patch initializes all the port devices, including those in the
unused "fake" ports. This makes the code more uniform because they
can all be released in the same way. The error handling code in
usb_serial_probe() is much simplified by this approach; instead of
freeing everything by hand we can use a single usb_serial_put() call.
Also simplified is the port-release mechanism. Instead of being two
separate routines, port_release() and port_free() can be combined into
one.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Various drivers have hacks to mangle termios structures. This stems from
the fact there is no nice setup hook for configuring the termios settings
when the port is created
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
And indeed none of them use it. Clean this up as it will make moving to a
standard open method rather easier.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The USB layer uses tty_hangup to deal with unplugs of the physical hardware
(analogous to loss of carrier) and then frees the resources. However the
tty_hangup is asynchronous. As the hangup can sleep we can use tty_vhangup
which is the non async version to avoid freeing resources too early.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This fixes
- locking bug that was hidden by ecc2e05e73
- Regression #13821
- Spurious warning when closing and blocking for data write out
With these changes my PL2303 always ends up as ttyUSB0 when it should and
the module refcounts stay correct.
I'll do a more wholesale split & tidy of _open in the next release or two
as we get a standard tty_port_open and port->ops->init port->ops->shutdown
call backs.
Copy sent to Alan Stern and Carlos Mafra just to confirm it fixes all the
reports but it passes local testing with the same hardware as Alan Stern.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The port lock is used to protect the port state. However the port structure
is freed on a hangup, then the lock taken on a close. The right fix is to
drop the port on tty->shutdown() but we can't yet do that due to sleep v
non-sleeping rules. Instead do the next best thing and fix it up when we are
not in -rc season.
Reported-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Tested-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The commit 335f8514f2 introduced a
regression which stopped usb consoles from working correctly as a
kernel boot console as well as interactive login device.
The addition of the serial_close() which in turn calls
tty_port_close_start() will change the reference count of port.count
and warn about it. The usb console code had previously incremented
the port.count to indicate it was making use of the device as a
console and the forced change causes a double open on the usb device
which leads to a non obvious kernel oops later on when the tty is
freed.
To fix the problem instead make use of port->console to track if the
port is in fact an active console port to avoid double initialization
of the usb serial device. The port.count is incremented and
decremented only with in the scope of usb_console_setup() for the
purpose of the low level driver initialization.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* Remove smp_lock.h from files which don't need it (including some headers!)
* Add smp_lock.h to files which do need it
* Make smp_lock.h include conditional in hardirq.h
It's needed only for one kernel_locked() usage which is under CONFIG_PREEMPT
This will make hardirq.h inclusion cheaper for every PREEMPT=n config
(which includes allmodconfig/allyesconfig, BTW)
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit 335f8514f2 has stopped
properly checking if there is any usb serial associated with the tty in
the close function. It happens the close function is called by releasing
the terminal right after opening the device fails.
As an example, open fails with a non-existing device, when probe has
never been called, because the device has never been plugged. This is
common in systems with static modules and no udev.
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1253) prevents the usb-serial core from calling a
driver's port_probe and port_remove methods more than once per port.
It also removes some unnecessary try_module_get() calls and adds a
missing port_remove method call in a failure path.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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 <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch (as1244) fixes a crash in usb-serial that occurs when a
sub-driver returns a positive value from its attach method, indicating
that new firmware was loaded and the device will disconnect and
reconnect. The usb-serial core then skips the step of registering the
port devices; when the disconnect occurs, the attempt to unregister
the ports fails dramatically.
This problem shows up with Keyspan devices and it might affect others
as well.
When the attach method returns a positive value, the patch sets
num_ports to 0. This tells usb_serial_disconnect() not to try
unregistering any of the ports; instead they are cleaned up by
destroy_serial().
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as1229) fixes a few lifetime and locking problems in the
usb-serial driver. The main symptom is that an invalid kevent is
created when the serial device is unplugged while a connection is
active.
Ports should be unregistered when device is disconnected,
not when the parent usb_serial structure is deallocated.
Each open file should hold a reference to the corresponding
port structure, and the reference should be released when
the file is closed.
serial->disc_mutex should be acquired in serial_open(), to
resolve the classic race between open and disconnect.
serial_close() doesn't need to hold both serial->disc_mutex
and port->mutex at the same time.
Release the subdriver's module reference only after releasing
all the other references, in case one of the release routines
needs to invoke some code in the subdriver module.
Replace a call to flush_scheduled_work() (which is prone to
deadlocks) with cancel_work_sync(). Also, add a call to
cancel_work_sync() in the disconnect routine.
Reduce the scope of serial->disc_mutex in serial_disconnect().
The only place it really needs to protect is where the
"disconnected" flag is set.
This fixes the bug reported in
http://bugs.freedesktop.org/show_bug.cgi?id=20703
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Dan Williams <dcbw@redhat.com>
Tested-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Oliver Neukum <oliver@neukum.org>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
With "nousb" cmdline booting, built-in serial drivers (ie. airecable)
will trigger kernel oops.
Indeed, if nousb, usb_serial_init will failed, and the usb serial bus type
will not be registerd, then usb_serial_register call driver_register
which try to register the driver to a not registered bus.
Here add usb_disabled() check in usb_serial_register to fix it.
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
A USB-serial converter device is plugged into a system, and a process
opens it's device node. If the device is physically removed whilst the
process still has its device node open, then other processes can
sucessfully open the now non-existent device's node. I would expect
that open() on a device that has been physically removed should return
ENODEV.
This is manifesting itself with getty on my system. I do the following:
1. set up inittab to spawn getty on ttyUSB0, eg:
T1:23:respawn:/sbin/getty -L ttyUSB0 115200 vt100
2. Plug in USB-serial converter cable
3. Wait for a login prompt on a terminal program attached to the serial
cable
4. Login
5. Pull the USB-serial converter cable from the box
6. getty doesn't realise that ttyUSB0 no longer exists as /dev/ttyUSB0
can still be opened.
7. Re-insert the USB-serial converter cable
8. You should no longer get a login prompt over the serial cable, as
the the USB-serial cable now shows up as /dev/ttyUSB1, and getty is
trying to talk to /dev/ttyUSB0.
The attached patch will cause open("/dev/ttyUSB0", O_RDONLY) to return
ENODEV after the USB-serial converter has been pulled. The patch was
created against 2.6.28.1. I can supply it against something else if
needs be. It is fairly simple, so should be OK.
I am using a pl2303 device, although I don't think that makes any
difference.
From: James Woodcock <James.Woodcock@ACULAB.COM>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This removes the fallback to the generic method. It is cleaner to
explicitely request it. Introducing this was my mistake. This will
be solved by an explicit test and the driver being allowed to request
what it needs to be done upon resumption.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch makes use of the generic method if a serial driver provides
no implementation. This simplifies implementing suspend/resume support
in serial drivers.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch introduces a flag into the usb serial layer to tell drivers
that their URBs are killed due to suspension. That is necessary to let
drivers know whether they should report an error back.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Hi Greg,
this is for 2.6.30. Patches to use this in drivers are under development.
Regards
Oliver
Julia Lawell found a case where a NULL check was misplaced in the
usb-serial code. However as the object in question cannot be NULL the
check can simply be removed.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't need the BKL here any more so it can go. In a couple of spots the
driver requirements are not clear so push the lock down into the driver.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
