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For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't currently harmful.
However, for some new features (e.g. KTSAN / Kernel Thread Sanitizer),
it is necessary to instrument reads and writes separately, which is not
possible with ACCESS_ONCE(). This distinction is critical to correct
operation.
It's possible to transform the bulk of kernel code using the Coccinelle
script below. However, for some files (including the ath9k ar9002 mac
driver), this mangles the formatting. As a preparatory step, this patch
converts the driver to use {READ,WRITE}_ONCE() without said mangling.
----
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: ath9k-devel@qca.qualcomm.com
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org
Cc: ath9k-devel@lists.ath9k.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.