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cb174344bf
[ Upstream commit e599046994 ]
When serial console over USB is enabled, gs_console_connect
queues gs_console_work, where it acquires the spinlock and
queues the usb request, and this request goes to gadget layer.
Now consider a situation where gadget layer prints something
to dmesg, this will eventually call gs_console_write() which
requires cons->lock. And this causes spinlock recursion. Avoid
this by excluding usb_ep_queue from the spinlock.
spin_lock_irqsave //needs cons->lock
gs_console_write
.
.
_printk
__warn_printk
dev_warn/pr_err
.
.
[USB Gadget Layer]
.
.
usb_ep_queue
gs_console_work
__gs_console_push // acquires cons->lock
process_one_work
Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
Link: https://lore.kernel.org/r/1683638872-6885-1-git-send-email-quic_prashk@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.