usb: Remove redundant 'flush_workqueue()' calls

'destroy_workqueue()' already drains the queue before destroying it, so
there is no need to flush it explicitly.

Remove the redundant 'flush_workqueue()' calls.

This was generated with coccinelle:

@@
expression E;
@@
- flush_workqueue(E);
destroy_workqueue(E);

Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Peter Chen <peter.chen@kernel.or> # for chipidea part
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/563123a8117d6cafae3f134e497587bd2b8bb7f4.1636734453.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usbip: synchronize event handler with sysfs code paths

Fuzzing uncovered race condition between sysfs code paths in usbip
drivers. Device connect/disconnect code paths initiated through
sysfs interface are prone to races if disconnect happens during
connect and vice versa.

Use sysfs_lock to synchronize event handler with sysfs paths
in usbip drivers.

Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/c5c8723d3f29dfe3d759cfaafa7dd16b0dfe2918.1616807117.git.skhan@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usbip: usbip_event: fix to not print kernel pointer address

Fix it to not print kernel pointer address. Remove the conditional
and debug message as it isn't very useful.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: usbip: Remove redundant license text

Now that the SPDX tag is in all USB files, that identifies the license
in a specific and legally-defined manner. So the extra GPL text wording
can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text. And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Valentina Manea <valentina.manea.m@gmail.com>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: add SPDX identifiers to all remaining files in drivers/usb/

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the drivers/usb/ and include/linux/usb* files with the correct
SPDX license identifier based on the license text in the file itself.
The SPDX identifier is a legally binding shorthand, which can be used
instead of the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usbip: event handler as one thread

Dear all,

1. Overview

In current USB/IP implementation, event kernel threads are created for
each port. The functions of the threads are closing connection and
error handling so they don't have not so many events to handle. There's
no need to have thread for each port.

BEFORE) vhci side - VHCI_NPORTS(8) threads are created.
$ ps aux | grep usbip
root 10059 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]
root 10060 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]
root 10061 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]
root 10062 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]
root 10063 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]
root 10064 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]
root 10065 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]
root 10066 0.0 0.0 0 0 ? S 17:06 0:00 [usbip_eh]

BEFORE) stub side - threads will be created every bind operation.
$ ps aux | grep usbip
root 8368 0.0 0.0 0 0 ? S 17:56 0:00 [usbip_eh]
root 8399 0.0 0.0 0 0 ? S 17:56 0:00 [usbip_eh]

This patch put event threads of stub and vhci driver as one workqueue.

AFTER) only one event threads in each vhci and stub side.
$ ps aux | grep usbip
root 10457 0.0 0.0 0 0 ? S< 17:47 0:00 [usbip_event]

2. Modification to usbip_event.c

BEFORE) kernel threads are created in usbip_start_eh().

AFTER) one workqueue is created in new usbip_init_eh().

Event handler which was main loop of kernel thread is modified to
workqueue handler.

Events themselves are stored in struct usbip_device - same as before.
usbip_devices which have event are listed in event_list.

The handler picks an element from the list and wakeup usbip_device. The
wakeup method is same as before.

usbip_in_eh() substitutes statement which checks whether functions are
called from eh_ops or not. In this function, the worker context is used
for the checking. The context will be set in a variable in the
beginning of first event handling. usbip_in_eh() is used in event
handler so it works well.

3. Modifications to programs using usbip_event.c

Initialization and termination of workqueue are added to init and exit
routine of usbip_core respectively.

A. version info

v2)
# Merged 1/2 event handler itself and 2/2 user programs because of auto
build fail at 1/2 casued unmodified user programs in 1/2.

Signed-off-by: Nobuo Iwata <nobuo.iwata@fujixerox.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: usbip: Fix possible deadlocks reported by lockdep

Change spin_lock calls to spin_lock_irqsave to prevent
attmpted recursive lock taking in interrupt context.

This patch fixes Bug 109351
https://bugzilla.kernel.org/show_bug.cgi?id=109351

Signed-off-by: Andrew Goodbody <andrew.goodbody@cambrionix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usbip: move usbip kernel code out of staging

At this point, USB/IP kernel code is fully functional
and can be moved out of staging.

Signed-off-by: Valentina Manea <valentina.manea.m@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>