USB: gadget: f_printer: make usb_gadget_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the usb_gadget_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at load time.

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Link: https://lore.kernel.org/r/20230620094412.508580-10-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: printer: Replace strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of PAGE_SIZE.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Link: https://lore.kernel.org/r/20230615180318.400639-1-azeemshaikh38@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

driver core: class: remove module * from class_create()

The module pointer in class_create() never actually did anything, and it
shouldn't have been requred to be set as a parameter even if it did
something. So just remove it and fix up all callers of the function in
the kernel tree at the same time.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20230313181843.1207845-4-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: Simplify diagnostic messaging in printer

Don't issue messages which can be easily achieved with ftrace.
In case of printer_open() the return code is propagated to other layers
so the user will know about -EBUSY anyway.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Link: https://lore.kernel.org/r/20221123110746.59611-1-andrzej.p@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: fix dangling pnp_string in f_printer.c

When opts->pnp_string is changed with configfs, new memory is allocated for
the string. It does not, however, update dev->pnp_string, even though the
memory is freed. When rquesting the string, the host then gets old or
corrupted data rather than the new string. The ieee 1284 id string should
be allowed to change while the device is connected.

The bug was introduced in commit fdc01cc286be ("usb: gadget: printer:
Remove pnp_string static buffer"), which changed opts->pnp_string from a
char[] to a char*.
This patch changes dev->pnp_string from a char* to a char** pointing to
opts->pnp_string.

Fixes: fdc01cc286be ("usb: gadget: printer: Remove pnp_string static buffer")
Signed-off-by: Albert Briscoe <albertsbriscoe@gmail.com>
Link: https://lore.kernel.org/r/20220911223753.20417-1-albertsbriscoe@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: printer: use list_move instead of list_del/list_add

Using list_move() instead of list_del() + list_add().

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20210609070612.1325044-1-libaokun1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fix various gadgets null ptr deref on 10gbps cabling.

This avoids a null pointer dereference in
f_{ecm,eem,hid,loopback,printer,rndis,serial,sourcesink,subset,tcm}
by simply reusing the 5gbps config for 10gbps.

Fixes: eaef50c76057 ("usb: gadget: Update usb_assign_descriptors for SuperSpeedPlus")
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Michael R Sweet <msweet@msweet.org>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Pawel Laszczak <pawell@cadence.com>
Cc: Peter Chen <peter.chen@nxp.com>
Cc: Sudhakar Panneerselvam <sudhakar.panneerselvam@oracle.com>
Cc: Wei Ming Chen <jj251510319013@gmail.com>
Cc: Will McVicker <willmcvicker@google.com>
Cc: Zqiang <qiang.zhang@windriver.com>
Reviewed-By: Lorenzo Colitti <lorenzo@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Link: https://lore.kernel.org/r/20210608044141.3898496-1-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: fix typo in f_printer.c

In line 824, it is trying to enable `out_ep`, so I
believe that in line 826, it should print `out_ep`
instead of `in_ep`.

Signed-off-by: Wei Ming Chen <jj251510319013@gmail.com>
Link: https://lore.kernel.org/r/20210214121929.9750-1-jj251510319013@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: gadget: f_printer: set a default q_len

The usb_f_printer gadget driver uses a default q_len value of *0* which prevents
any IO from occurring. Moreover, once the driver is instantiated it is
impossible to change the q_len value.

The following patch uses a default q_len value of 10 which matches the legacy
g_printer gadget driver. This minimizes the possibility that you end up with a
non-working printer gadget. It is still possible to set the q_len to a
different value using the configfs path of the same name.

Signed-off-by: Michael R Sweet <msweet@msweet.org>
Link: https://lore.kernel.org/r/9DFB1605-63A5-46DB-A5A4-B59B315D8115@msweet.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: printer: Fix a memory leak for interface descriptor

When printer driver is loaded, the printer_func_bind function is called, in
this function, the interface descriptor be allocated memory, if after that,
the error occurred, the interface descriptor memory need to be free.

Reviewed-by: Peter Chen <peter.chen@nxp.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Link: https://lore.kernel.org/r/20201210020148.6691-1-qiang.zhang@windriver.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: printer: fix use-after-free in __lock_acquire

Fix this by increase object reference count.

BUG: KASAN: use-after-free in __lock_acquire+0x3fd4/0x4180
kernel/locking/lockdep.c:3831
Read of size 8 at addr ffff8880683b0018 by task syz-executor.0/3377

CPU: 1 PID: 3377 Comm: syz-executor.0 Not tainted 5.6.11 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xce/0x128 lib/dump_stack.c:118
print_address_description.constprop.4+0x21/0x3c0 mm/kasan/report.c:374
__kasan_report+0x131/0x1b0 mm/kasan/report.c:506
kasan_report+0x12/0x20 mm/kasan/common.c:641
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
__lock_acquire+0x3fd4/0x4180 kernel/locking/lockdep.c:3831
lock_acquire+0x127/0x350 kernel/locking/lockdep.c:4488
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159
printer_ioctl+0x4a/0x110 drivers/usb/gadget/function/f_printer.c:723
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0xfb/0x130 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770
do_syscall_64+0x9e/0x510 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4531a9
Code: ed 60 fc ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 0f 83 bb 60 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd14ad72c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000073bfa8 RCX: 00000000004531a9
RDX: fffffffffffffff9 RSI: 000000000000009e RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004bbd61
R13: 00000000004d0a98 R14: 00007fd14ad736d4 R15: 00000000ffffffff

Allocated by task 2393:
save_stack+0x21/0x90 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
__kasan_kmalloc.constprop.3+0xa7/0xd0 mm/kasan/common.c:515
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529
kmem_cache_alloc_trace+0xfa/0x2d0 mm/slub.c:2813
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:669 [inline]
gprinter_alloc+0xa1/0x870 drivers/usb/gadget/function/f_printer.c:1416
usb_get_function+0x58/0xc0 drivers/usb/gadget/functions.c:61
config_usb_cfg_link+0x1ed/0x3e0 drivers/usb/gadget/configfs.c:444
configfs_symlink+0x527/0x11d0 fs/configfs/symlink.c:202
vfs_symlink+0x33d/0x5b0 fs/namei.c:4201
do_symlinkat+0x11b/0x1d0 fs/namei.c:4228
__do_sys_symlinkat fs/namei.c:4242 [inline]
__se_sys_symlinkat fs/namei.c:4239 [inline]
__x64_sys_symlinkat+0x73/0xb0 fs/namei.c:4239
do_syscall_64+0x9e/0x510 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 3368:
save_stack+0x21/0x90 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
kasan_set_free_info mm/kasan/common.c:337 [inline]
__kasan_slab_free+0x135/0x190 mm/kasan/common.c:476
kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
slab_free_hook mm/slub.c:1444 [inline]
slab_free_freelist_hook mm/slub.c:1477 [inline]
slab_free mm/slub.c:3034 [inline]
kfree+0xf7/0x410 mm/slub.c:3995
gprinter_free+0x49/0xd0 drivers/usb/gadget/function/f_printer.c:1353
usb_put_function+0x38/0x50 drivers/usb/gadget/functions.c:87
config_usb_cfg_unlink+0x2db/0x3b0 drivers/usb/gadget/configfs.c:485
configfs_unlink+0x3b9/0x7f0 fs/configfs/symlink.c:250
vfs_unlink+0x287/0x570 fs/namei.c:4073
do_unlinkat+0x4f9/0x620 fs/namei.c:4137
__do_sys_unlink fs/namei.c:4184 [inline]
__se_sys_unlink fs/namei.c:4182 [inline]
__x64_sys_unlink+0x42/0x50 fs/namei.c:4182
do_syscall_64+0x9e/0x510 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880683b0000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 24 bytes inside of
1024-byte region [ffff8880683b0000, ffff8880683b0400)
The buggy address belongs to the page:
page:ffffea0001a0ec00 refcount:1 mapcount:0 mapping:ffff88806c00e300
index:0xffff8880683b1800 compound_mapcount: 0
flags: 0x100000000010200(slab|head)
raw: 0100000000010200 0000000000000000 0000000600000001 ffff88806c00e300
raw: ffff8880683b1800 000000008010000a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Reported-by: Kyungtae Kim <kt0755@gmail.com>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

usb: gadget: function: printer: Interface is disabled and returns error

After the device is disconnected from the host side, the interface of
the device is reset. If the userspace operates the device again,
an error code should be returned.

Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

usb: gadget: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200707171500.GA13620@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: function: printer: avoid wrong list handling in printer_write()

When printer_write() calls usb_ep_queue(), a udc driver (e.g.
renesas_usbhs driver) may call usb_gadget_giveback_request() in
the udc .queue ops immediately. Then, printer_write() calls
list_add(&req->list, &dev->tx_reqs_active) wrongly. After that,
if we do unbind the printer driver, WARN_ON() happens in
printer_func_unbind() because the list entry is not removed.

So, this patch moves list_add(&req->list, &dev->tx_reqs_active)
calling before usb_ep_queue().

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

vfs: do bulk POLL* -> EPOLL* replacement

This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

the rest of drivers/*: annotate ->poll() instances

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

USB: gadget: function: 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: Oliver Neukum <oneukum@suse.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Jerry Zhang <zhangjerry@google.com>
Cc: John Keeping <john@metanate.com>
Cc: Krzysztof Opasiak <k.opasiak@samsung.com>
Cc: Abdulhadi Mohamed <abdulahhadi2@gmail.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Janusz Dziedzic <januszx.dziedzic@linux.intel.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Vincent Pelletier <plr.vincent@gmail.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>

usb: gadget: make config_item_type structures const

Make these structures const as they are only passed to the const
argument of the functions config_{group/item}_init_type_name.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

usb: gadget: function: printer: avoid spinlock recursion

If usb_gadget_giveback_request() is called in usb_ep_queue(),
this printer_write() is possible to cause spinlock recursion. So,
this patch adds spin_unlock() before calls usb_ep_queue() to avoid it.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: gadget: printer: Remove pnp_string static buffer

pnp string is usually much shorter than 1k so let's stop wasting 1k of
memory for its buffer and make it dynamically alocated.
This also removes 1k len limitation for pnp_string and
adds a new line after string content if required.

Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

idr: add ida_is_empty

Two of the USB Gadgets were poking around in the internals of struct ida
in order to determine if it is empty. Add the appropriate abstraction.

Link: http://lkml.kernel.org/r/1480369871-5271-63-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

usb: gadget: composite: let USB functions process ctrl reqs in cfg0

It can sometimes be necessary for gadget drivers to process non-standard
control requests, which host devices can send without having sent
USB_REQ_SET_CONFIGURATION.

Therefore, the req_match() usb_function method is enhanced with the new
parameter "config0". When a USB configuration is active, this parameter
is false. When a non-core control request is processed in
composite_setup(), without an active configuration, req_match() of the
USB functions of all available configurations which implement this
function, is called with config0=true. Then the control request gets
processed by the first usb_function instance whose req_match() returns
true.

Signed-off-by: Felix Hädicke <felixhaedicke@web.de>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: gadget: printer: Drop unused device qualifier descriptor

This descriptor is never used. Currently device qualifier
descriptor is generated by compossite code, so no need to
keep it in function file.

Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Krzysztof Opasiak <kopasiak90@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: gadget: Update usb_assign_descriptors for SuperSpeedPlus

Add the 'ssp_descriptors' parameter to the usb_assign_descriptors()
function. This allows a function driver to add descriptors for
SuperSpeedPlus speeds if it supports it.

Also update all uses of this function in the gadget subsystem so that
they pass NULL for the ssp_descriptors parameters.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

usb-gadget/f_printer: use per-attribute show and store methods

To simplify the configfs interface and remove boilerplate code that also
causes binary bloat.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

usb: gadget: f_printer: eliminate abuse of ep->driver data

Since ep->driver_data is not used for endpoint claiming, neither for
enabled/disabled state storing, we can reduce number of places where
we read or modify it's value, as now it has no particular meaning for
function or framework logic.

In case of f_printer we only need to store in ep->driver_data pointer to
struct printer_dev, as it's used in rx_complete() and tx_complete()
callbacks. All other uses of ep->driver_data are now meaningless and can
be safely removed.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: f_printer: fix deadlock caused by nested spinlock

Function printer_func_disable() has called spinlock on printer_dev->lock,
and it'll call function chain of

printer_reset_interface()
|
+---dwc3_gadget_ep_disable()
|
+---__dwc3_gadget_ep_disable()
|
+---dwc3_remove_requests()
|
+---dwc3_gadget_giveback()
|
+---rx_complete()

in the protected block.

However, rx_complete() in f_printer.c calls spinlock on printer_dev->lock
again, which will cause system hang.

The following steps can reproduce this hang:

1. Build the test program from Documentation/usb/gadget_printer.txt as
g_printer
2. Plug in the USB device to a host(such as Ubuntu).
3. on the USB device system run:
#modprobe g_printer.ko
#./g_printer -read_data

4. Unplug the USB device from the host

The system will hang later.

In order to avoid this deadlock, moving the spinlock from
printer_func_disable() into printer_reset_interface() and excluding the block
of calling dwc3_gadget_ep_disable(), in which the critical resource will be
protected by its spinlock in rx_complete().

This commit will fix the system hang with the following calltrace:

INFO: rcu_preempt detected stalls on CPUs/tasks: { 3} (detected by 0, t=21006 jiffies, g=524, c=523, q=2)
sending NMI to all CPUs:
NMI backtrace for cpu 3
CPU: 3 PID: 718 Comm: irq/22-dwc3 Not tainted 3.10.38-ltsi-WR6.0.0.11_standard #2
Hardware name: Intel Corp. VALLEYVIEW B3 PLATFORM/NOTEBOOK, BIOS BYTICRB1.86C.0092.R32.1410021707 10/02/2014
task: f44f4c20 ti: f40f6000 task.ti: f40f6000
EIP: 0060:[<c1824955>] EFLAGS: 00000097 CPU: 3
EIP is at _raw_spin_lock_irqsave+0x35/0x40
EAX: 00000076 EBX: f80fad00 ECX: 00000076 EDX: 00000075
ESI: 00000096 EDI: ffffff94 EBP: f40f7e20 ESP: f40f7e18
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
CR0: 8005003b CR2: b77ac000 CR3: 01c30000 CR4: 001007f0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff0ff0 DR7: 00000400
Stack:
f474a720 f80fad00 f40f7e3c f80f93cc c135d486 00000000 f474a720 f468fb00
f4bea894 f40f7e54 f7e35f19 ffffff00 f468fb00 f468fb24 00000086 f40f7e64
f7e36577 f468fb00 f4bea810 f40f7e74 f7e365a8 f468fb00 f4bea894 f40f7e9c
Call Trace:
[<f80f93cc>] rx_complete+0x1c/0xb0 [g_printer]
[<c135d486>] ? vsnprintf+0x166/0x390
[<f7e35f19>] dwc3_gadget_giveback+0xc9/0xf0 [dwc3]
[<f7e36577>] dwc3_remove_requests+0x57/0x70 [dwc3]
[<f7e365a8>] __dwc3_gadget_ep_disable+0x18/0x60 [dwc3]
[<f7e366e9>] dwc3_gadget_ep_disable+0x89/0xf0 [dwc3]
[<f80f9031>] printer_reset_interface+0x31/0x50 [g_printer]
[<f80f9270>] printer_func_disable+0x20/0x30 [g_printer]
[<f80e6d8b>] composite_disconnect+0x4b/0x90 [libcomposite]
[<f7e39a8b>] dwc3_disconnect_gadget+0x38/0x43 [dwc3]
[<f7e39ad4>] dwc3_gadget_disconnect_interrupt+0x3e/0x5a [dwc3]
[<f7e373b8>] dwc3_thread_interrupt+0x5c8/0x610 [dwc3]
[<c10ac518>] irq_thread_fn+0x18/0x30
[<c10ac800>] irq_thread+0x100/0x130
[<c10ac500>] ? irq_finalize_oneshot.part.29+0xb0/0xb0
[<c10ac650>] ? wake_threads_waitq+0x40/0x40
[<c10ac700>] ? irq_thread_dtor+0xb0/0xb0
[<c1057224>] kthread+0x94/0xa0
[<c182b337>] ret_from_kernel_thread+0x1b/0x28
[<c1057190>] ? kthread_create_on_node+0xc0/0xc0

Signed-off-by: Fupan Li <fupan.li@windriver.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: f_printer: actually limit the number of instances

There is a predefined maximum number of printer instances, currently 4.
A chrdev region is allocated accordingly, but with configfs the user
can create as many printer function directories as they like. To make the
number of printer instances consistent with the number of allocated
minors, the limit is enforced at directory creation time.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: f_printer: use non-zero flag for bitwise and

USB_DIR_OUT happens to be zero, so the result of bitwise and is always 0.
Consequently, break will never happen in the SOFT_RESET case.
This patch uses a compatible condition with a non-zero USB_DIR_IN,
which might or might not evaluate to zero.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: printer: use after free in gprinter_alloc_inst()

There was a missing goto so we free "opts" and then dereference it.

Fixes: ee1cd515e889 ('usb: gadget: printer: add configfs support')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: printer: delete some dead code

"num" is a u16 so it can't go higher than 65535. kstrtou16() has a
range check built in so this is already handled.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: printer: add configfs support

Add support for configfs interface so that f_printer can be used as a
component of usb gadgets composed with it.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: f_printer: remove compatibility layer

There are no old interface users left, so it can be removed.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: f_printer: convert to new function interface with backward compatibility

In order to add configfs support, a usb function must be converted to use
the new interface. This patch converts the function to the new interface
and provides backward compatiblity layer, which can be removed after
all its users are converted to use the new interface.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: printer: factor out f_printer

The legacy printer gadget now contains both a reusable printer function
and legacy gadget proper implementations interwoven, but logically
separate. This patch factors out a reusable f_printer.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>