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Andrey Konovalov 3551ff7c5c usb: gadget: clarify usage of USB_GADGET_DELAYED_STATUS
USB_GADGET_DELAYED_STATUS was introduced in commit 1b9ba00017 ("usb:
gadget: composite: Allow function drivers to pause control transfers").
It was initially intended for the composite framework to allow delaying
completing the status stage of a SET_CONFIGURATION request until all
functions are ready.

Unfortunately, that commit had an unintended side-effect of returning
USB_GADGET_DELAYED_STATUS from the ->setup() call of the composite
framework gadget driver.

As a result of this and the incomplete documentation, some UDC drivers
started relying on USB_GADGET_DELAYED_STATUS to decide when to avoid
autocompleting the status stage for 0-length control transfers. dwc3 was
the first in commit 5bdb1dcc63 ("usb: dwc3: ep0: handle delayed_status
again"). And a number of other UDC drivers followed later, probably
relying on the dwc3 behavior as a reference.

Unfortunately, this violated the interface between the UDC and the
gadget driver for 0-length control transfers: the UDC driver must only
proceed with the status stage for a 0-length control transfer once the
gadget driver queued a response to EP0.

As a result, a few gadget drivers are partially broken when used with
a UDC that only delays the status stage for 0-length transfers when
USB_GADGET_DELAYED_STATUS is returned from the setup() callback.

This includes Raw Gadget and GadgetFS. For FunctionFS, a workaround was
added in commit 946ef68ad4 ("usb: gadget: ffs: Let setup() return
USB_GADGET_DELAYED_STATUS") and commit 4d644abf25 ("usb: gadget: f_fs:
Only return delayed status when len is 0").

The proper solution to this issue would be to contain
USB_GADGET_DELAYED_STATUS within the composite framework and make all
UDC drivers to not complete the status stage for 0-length requests on
their own.

Unfortunately, there is quite a few UDC drivers that need to get fixed
and the required changes for some of them are not trivial.

For now, update the comments to clarify that USB_GADGET_DELAYED_STATUS
must not be used by the UDC drivers.

The following two commits also add workarounds to Raw Gadget and GadgetFS
to make them compatible with the broken UDC drivers until they are fixed.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/7f0ee06c68c7241c844cd50f8565fdd5ead79b1b.1693237258.git.andreyknvl@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-02 16:43:04 +02:00
arch Fourteen hotfixes, eleven of which are cc:stable. The remainder pertain 2023-10-01 13:33:25 -07:00
block block: fix kernel-doc for disk_force_media_change() 2023-09-26 00:43:34 -06:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: sm2 - Fix crash caused by uninitialized context 2023-09-20 13:10:10 +08:00
Documentation usb: pd: Exposing the Peak Current value of Fixed Supplies to user space 2023-10-02 16:38:29 +02:00
drivers USB: c67x00: Remove unused declaration c67x00_hcd_msg_received() 2023-10-02 16:42:33 +02:00
fs Fourteen hotfixes, eleven of which are cc:stable. The remainder pertain 2023-10-01 13:33:25 -07:00
include usb: gadget: clarify usage of USB_GADGET_DELAYED_STATUS 2023-10-02 16:43:04 +02:00
init workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
io_uring io_uring/fs: remove sqe->rw_flags checking from LINKAT 2023-09-29 03:07:09 -06:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel Fourteen hotfixes, eleven of which are cc:stable. The remainder pertain 2023-10-01 13:33:25 -07:00
lib maple_tree: add MAS_UNDERFLOW and MAS_OVERFLOW states 2023-09-29 17:20:46 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm Fourteen hotfixes, eleven of which are cc:stable. The remainder pertain 2023-10-01 13:33:25 -07:00
net Networking fixes for 6.6-rc2, including fixes from netfilter and bpf 2023-09-21 11:28:16 -07:00
rust Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
samples VFIO updates for v6.6-rc1 2023-08-30 20:36:01 -07:00
scripts kbuild: remove stale code for 'source' symlink in packaging scripts 2023-10-01 23:06:06 +09:00
security selinux: fix handling of empty opts in selinux_fs_context_submount() 2023-09-12 17:31:08 -04:00
sound ASoC: Fixes for v6.6 2023-09-20 15:02:16 +02:00
tools Fourteen hotfixes, eleven of which are cc:stable. The remainder pertain 2023-10-01 13:33:25 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap for-linus-2023083101 2023-09-01 12:31:44 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS ARM: SoC fixes for 6.6 2023-09-30 18:41:37 -07:00
Makefile Linux 6.6-rc4 2023-10-01 14:15:13 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.