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[ Upstream commit 04d19e65137e3cd4a5004e624c85c762933d115c ] 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.