usb: gadget: storage: Remove reference counting

The kref used to be needed because sharing of fsg_common among multiple USB
function instances was handled by fsg. Now this is managed by configfs, we
don't need it anymore. So let's eliminate kref from this driver.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Jaejoong Kim <climbbb.kim@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: g_mass_storage: Fix deadlock when driver is unbound

As a holdover from the old g_file_storage gadget, the g_mass_storage
legacy gadget driver attempts to unregister itself when its main
operating thread terminates (if it hasn't been unregistered already).
This is not strictly necessary; it was never more than an attempt to
have the gadget fail cleanly if something went wrong and the main
thread was killed.

However, now that the UDC core manages gadget drivers independently of
UDC drivers, this scheme doesn't work any more. A simple test:

modprobe dummy-hcd
modprobe g-mass-storage file=...
rmmod dummy-hcd

ends up in a deadlock with the following backtrace:

sysrq: SysRq : Show Blocked State
task PC stack pid father
file-storage D 0 1130 2 0x00000000
Call Trace:
__schedule+0x53e/0x58c
schedule+0x6e/0x77
schedule_preempt_disabled+0xd/0xf
__mutex_lock.isra.1+0x129/0x224
? _raw_spin_unlock_irqrestore+0x12/0x14
__mutex_lock_slowpath+0x12/0x14
mutex_lock+0x28/0x2b
usb_gadget_unregister_driver+0x29/0x9b [udc_core]
usb_composite_unregister+0x10/0x12 [libcomposite]
msg_cleanup+0x1d/0x20 [g_mass_storage]
msg_thread_exits+0xd/0xdd7 [g_mass_storage]
fsg_main_thread+0x1395/0x13d6 [usb_f_mass_storage]
? __schedule+0x573/0x58c
kthread+0xd9/0xdb
? do_set_interface+0x25c/0x25c [usb_f_mass_storage]
? init_completion+0x1e/0x1e
ret_from_fork+0x19/0x24
rmmod D 0 1155 683 0x00000000
Call Trace:
__schedule+0x53e/0x58c
schedule+0x6e/0x77
schedule_timeout+0x26/0xbc
? __schedule+0x573/0x58c
do_wait_for_common+0xb3/0x128
? usleep_range+0x81/0x81
? wake_up_q+0x3f/0x3f
wait_for_common+0x2e/0x45
wait_for_completion+0x17/0x19
fsg_common_put+0x34/0x81 [usb_f_mass_storage]
fsg_free_inst+0x13/0x1e [usb_f_mass_storage]
usb_put_function_instance+0x1a/0x25 [libcomposite]
msg_unbind+0x2a/0x42 [g_mass_storage]
__composite_unbind+0x4a/0x6f [libcomposite]
composite_unbind+0x12/0x14 [libcomposite]
usb_gadget_remove_driver+0x4f/0x77 [udc_core]
usb_del_gadget_udc+0x52/0xcc [udc_core]
dummy_udc_remove+0x27/0x2c [dummy_hcd]
platform_drv_remove+0x1d/0x31
device_release_driver_internal+0xe9/0x16d
device_release_driver+0x11/0x13
bus_remove_device+0xd2/0xe2
device_del+0x19f/0x221
? selinux_capable+0x22/0x27
platform_device_del+0x21/0x63
platform_device_unregister+0x10/0x1a
cleanup+0x20/0x817 [dummy_hcd]
SyS_delete_module+0x10c/0x197
? ____fput+0xd/0xf
? task_work_run+0x55/0x62
? prepare_exit_to_usermode+0x65/0x75
do_fast_syscall_32+0x86/0xc3
entry_SYSENTER_32+0x4e/0x7c

What happens is that removing the dummy-hcd driver causes the UDC core
to unbind the gadget driver, which it does while holding the udc_lock
mutex. The unbind routine in g_mass_storage tells the main thread to
exit and waits for it to terminate.

But as mentioned above, when the main thread exits it tries to
unregister the mass-storage function driver. Via the composite
framework this ends up calling usb_gadget_unregister_driver(), which
tries to acquire the udc_lock mutex. The result is deadlock.

The simplest way to fix the problem is not to be so clever: The main
thread doesn't have to unregister the function driver. The side
effects won't be so terrible; if the gadget is still attached to a USB
host when the main thread is killed, it will appear to the host as
though the gadget's firmware has crashed -- a reasonably accurate
interpretation, and an all-too-common occurrence for USB mass-storage
devices.

In fact, the code to unregister the driver when the main thread exits
is specific to g-mass-storage; it is not used when f-mass-storage is
included as a function in a larger composite device. Therefore the
entire mechanism responsible for this (the fsg_operations structure
with its ->thread_exits method, the fsg_common_set_ops() routine, and
the msg_thread_exits() callback routine) can all be eliminated. Even
the msg_registered bitflag can be removed, because now the driver is
unregistered in only one place rather than in two places.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@vger.kernel.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: gadget: Add per-lun inquiry string

Introduce an attribute "inquiry_string" to the lun.

In some environments, e. g. BIOS boot menus, the inquiry string
is the only information about devices presented to the user. The
default string depends on the "cdrom" bit of the first lun as
well as the kernel version and allows no further customization.
So without access to the client it is not obvious which gadget is
active at a given point and what any of the available luns might
contain.

If "inquiry_string" is ignored or set to the empty string, the
old behavior is preserved.

Signed-off-by: Philipp Gesang <philipp.gesang@intra2net.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: f_mass_storage: test whether thread is running before starting another

When binding the function to usb_configuration, check whether the thread
is running before starting another one. Without that, when function
instance is added to multiple configurations, fsg_bing starts multiple
threads with all but the latest one being forgotten by the driver. This
leads to obvious thread leaks, possible lockups when trying to halt the
machine and possible more issues.

This fixes issues with legacy/multi¹ gadget as well as configfs gadgets
when mass_storage function is added to multiple configurations.

This change also simplifies API since the legacy gadgets no longer need
to worry about starting the thread by themselves (which was where bug
in legacy/multi was in the first place).

N.B., this patch doesn’t address adding single mass_storage function
instance to a single configuration twice. Thankfully, there’s no
legitimate reason for such setup plus, if I’m not mistaken, configfs
gadget doesn’t even allow it to be expressed.

¹ I have no example failure though. Conclusion that legacy/multi has
a bug is based purely on me reading the code.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Tested-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: <stable@vger.kernel.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: gadget: mass_storage: Use static array for luns

This patch replace dynamicly allocated luns array with static one.
This simplifies the code of mass storage function and modules.

Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>

usb: gadget: mass_storage: Fix freeing luns sysfs implementation

Use device_is_registered() instad of sysfs flag to determine if
we should free sysfs representation of particular LUN.

sysfs flag in fsg common determines if luns attributes should be
exposed using sysfs. This flag is used when creating and freeing
luns. Unfortunately there is no guarantee that this flag will not
be changed between creation and removal of particular LUN. Especially
because of lun.0 which is created during allocating instance of
function. This may lead to resource leak or NULL pointer dereference:

[ 62.539925] Unable to handle kernel NULL pointer dereference at virtual address 00000044
[ 62.548014] pgd = ec994000
[ 62.550679] [00000044] *pgd=6d7be831, *pte=00000000, *ppte=00000000
[ 62.556933] Internal error: Oops: 17 [#1] PREEMPT SMP ARM
[ 62.562310] Modules linked in: g_mass_storage(+)
[ 62.566916] CPU: 2 PID: 613 Comm: insmod Not tainted 4.2.0-rc4-00077-ge29ee91-dirty #125
[ 62.574984] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 62.581061] task: eca56e80 ti: eca76000 task.ti: eca76000
[ 62.586450] PC is at kernfs_find_ns+0x8/0xe8
[ 62.590698] LR is at kernfs_find_and_get_ns+0x30/0x48
[ 62.595732] pc : [<c01277c0>] lr : [<c0127b88>] psr: 40010053
[ 62.595732] sp : eca77c40 ip : eca77c38 fp : 000008c1
[ 62.607187] r10: 00000001 r9 : c0082f38 r8 : ed41ce40
[ 62.612395] r7 : c05c1484 r6 : 00000000 r5 : 00000000 r4 : c0814488
[ 62.618904] r3 : 00000000 r2 : 00000000 r1 : c05c1484 r0 : 00000000
[ 62.625417] Flags: nZcv IRQs on FIQs off Mode SVC_32 ISA ARM Segment user
[ 62.632620] Control: 10c5387d Table: 6c99404a DAC: 00000015
[ 62.638348] Process insmod (pid: 613, stack limit = 0xeca76210)
[ 62.644251] Stack: (0xeca77c40 to 0xeca78000)
[ 62.648594] 7c40: c0814488 00000000 00000000 c05c1484 ed41ce40 c0127b88 00000000 c0824888
[ 62.656753] 7c60: ed41d038 ed41d030 ed41d000 c012af4c 00000000 c0824858 ed41d038 c02e3314
[ 62.664912] 7c80: ed41d030 00000000 ed41ce04 c02d9e8c c070eda8 eca77cb4 000008c1 c058317c
[ 62.673071] 7ca0: 000008c1 ed41d030 ed41ce00 ed41ce04 ed41d000 c02da044 ed41cf48 c0375870
[ 62.681230] 7cc0: ed9d3c04 ed9d3c00 ed52df80 bf000940 fffffff0 c03758f4 c03758c0 00000000
[ 62.689389] 7ce0: bf000564 c03614e0 ed9d3c04 bf000194 c0082f38 00000001 00000000 c0000100
[ 62.697548] 7d00: c0814488 c0814488 c086b1dc c05893a8 00000000 ed7e8320 00000000 c0128b88
[ 62.705707] 7d20: ed8a6b40 00000000 00000000 ed410500 ed8a6b40 c0594818 ed7e8320 00000000
[ 62.713867] 7d40: 00000000 c0129f20 00000000 c082c444 ed8a6b40 c012a684 00001000 00000000
[ 62.722026] 7d60: c0594818 c082c444 00000000 00000000 ed52df80 ed52df80 00000000 00000000
[ 62.730185] 7d80: 00000000 00000000 00000001 00000002 ed8e9b70 ed52df80 bf0006d0 00000000
[ 62.738345] 7da0: ed8e9b70 ed410500 ed618340 c036129c ed8c1c00 bf0006d0 c080b158 ed8c1c00
[ 62.746504] 7dc0: bf0006d0 c080b158 ed8c1c08 ed410500 c0082f38 ed618340 000008c1 c03640ac
[ 62.754663] 7de0: 00000000 bf0006d0 c082c8dc c080b158 c080b158 c03642d4 00000000 bf003000
[ 62.762822] 7e00: 00000000 c0009784 00000000 00000001 00000000 c05849b0 00000002 ee7ab780
[ 62.770981] 7e20: 00000002 ed4105c0 0000c53e 000000d0 c0808600 eca77e5c 00000004 00000000
[ 62.779140] 7e40: bf000000 c0095680 c08075a0 ee001f00 ed4105c0 c00cadc0 ed52df80 bf000780
[ 62.787300] 7e60: ed4105c0 bf000780 00000001 bf0007c8 c0082f38 ed618340 000008c1 c0083e24
[ 62.795459] 7e80: 00000001 bf000780 00000001 eca77f58 00000001 bf000780 00000001 c00857f4
[ 62.803618] 7ea0: bf00078c 00007fff 00000000 c00835b4 eca77f58 00000000 c0082fac eca77f58
[ 62.811777] 7ec0: f05038c0 0003b008 bf000904 00000000 00000000 bf00078c 6e72656b 00006c65
[ 62.819936] 7ee0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 62.828095] 7f00: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 62.836255] 7f20: 00000000 00000000 00000000 00000000 00000000 00000000 00000003 0003b008
[ 62.844414] 7f40: 0000017b c000f5c8 eca76000 00000000 0003b008 c0085df8 f04ef000 0001b8a9
[ 62.852573] 7f60: f0503258 f05030c2 f0509fe8 00000968 00000dc8 00000000 00000000 00000000
[ 62.860732] 7f80: 00000029 0000002a 00000011 00000000 0000000a 00000000 33f6eb00 0003b008
[ 62.868892] 7fa0: bef01cac c000f400 33f6eb00 0003b008 00000003 0003b008 00000000 00000003
[ 62.877051] 7fc0: 33f6eb00 0003b008 bef01cac 0000017b 00000000 0003b008 0000000b 0003b008
[ 62.885210] 7fe0: bef01ae0 bef01ad0 0001dc23 b6e8c162 800b0070 00000003 c0c0c0c0 c0c0c0c0
[ 62.893380] [<c01277c0>] (kernfs_find_ns) from [<c0824888>] (pm_qos_latency_tolerance_attr_group+0x0/0x10)
[ 62.903005] Code: e28dd00c e8bd80f0 e92d41f0 e2923000 (e1d0e4b4)
[ 62.909115] ---[ end trace 02fb4373ef095c7b ]---

Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

usb: gadget: Gadget directory cleanup - group usb functions

The drivers/usb/gadget directory contains many files.
Files which are related can be distributed into separate directories.
This patch moves the USB functions implementations into a separate directory.

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