Chengfeng Ye
e6571cff84
[ Upstream commit 04d19e6513 ]
As &dev->condlock is acquired under irq context along the following
call chain from s5p_mfc_irq(), other acquisition of the same lock
inside process context or softirq context should disable irq avoid double
lock. enc_post_frame_start() seems to be one such function that execute
under process context or softirq context.
<deadlock #1>
enc_post_frame_start()
--> clear_work_bit()
--> spin_loc(&dev->condlock)
<interrupt>
--> s5p_mfc_irq()
--> s5p_mfc_handle_frame()
--> clear_work_bit()
--> spin_lock(&dev->condlock)
This flaw was found by an experimental static analysis tool I am
developing for irq-related deadlock.
To prevent the potential deadlock, the patch change clear_work_bit()
inside enc_post_frame_start() to clear_work_bit_irqsave().
Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
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.