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As kcs_bmc_handle_event() is executed inside both a timer and a hardirq,
it should disable irq before lock acquisition otherwise deadlock could
happen if the timmer is preemtped by the irq.
Possible deadlock scenario:
aspeed_kcs_check_obe() (timer)
-> kcs_bmc_handle_event()
-> spin_lock(&kcs_bmc->lock)
<irq interruption>
-> aspeed_kcs_irq()
-> kcs_bmc_handle_event()
-> spin_lock(&kcs_bmc->lock) (deadlock here)
This flaw was found using an experimental static analysis tool we are
developing for irq-related deadlock.
The tentative patch fix the potential deadlock by spin_lock_irqsave()
Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
Message-Id: <20230627152449.36093-1-dg573847474@gmail.com>
Signed-off-by: Corey Minyard <minyard@acm.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.