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be9c336852
The req_lock is currently implemented as a rw_lock, but there are no instances where read_lock() is called. This means that the lock is effectively only used by writers, making it functionally equivalent to a simple spinlock. As stated in Documentation/locking/spinlocks.rst: "Reader-writer locks require more atomic memory operations than simple spinlocks. Unless the reader critical section is long, you are better off just using spinlocks." Since the rw_lock in this case incurs additional atomic memory operations without any benefit from reader-writer locking, it is more efficient to replace it with a spinlock. This patch implements that replacement to optimize the driver's performance. Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 reStructuredText 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.