kernel/samples/mic/mpssd/mpssd.c, branch linux-5.1.yHosts the 0x221E linux distro kernel.https://universe.0xinfinity.dev/distro/kernel/atom?h=linux-5.1.y2017-10-25T09:01:01Zlocking/atomics, samples/mic/mpssd/mpssd.c: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_ONCE()2017-10-25T09:01:01ZMark Rutlandmark.rutland@arm.com2017-10-23T21:07:20Zurn:sha1:94bbc9c1a0b0967509f8ad91323245aad30572f7
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 features it is necessary to instrument reads and
writes separately, which is not possible with ACCESS_ONCE(). This
distinction is critical to correct operation.
The bulk of the kernel code can be transformed via Coccinelle to use
{READ,WRITE}_ONCE(), though this only modifies users of ACCESS_ONCE(),
and not the implementation itself. As such, it has the potential to
break homebrew ACCESS_ONCE() macros seen in some user code in the kernel
tree (e.g. the virtio code, as fixed in commit ea9156fb3b71d9f7).
To avoid fragility if/when that transformation occurs, and to align with
the preferred usage of {READ,WRITE}_ONCE(), this patch updates the MPSSD
sample code to use READ_ONCE() rather than ACCESS_ONCE(). There should
be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-10-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
samples: move mic/mpssd example code from Documentation2016-09-20T18:38:48ZShuah Khanshuahkh@osg.samsung.com2016-09-16T21:53:52Zurn:sha1:6bee835dd54e279f3d3ae2eca92a9c394b4fd028
Move mic/mpssd examples to samples and remove it from Documentation
Makefile. Create a new Makefile to build mic/mpssd. It can be built
from top level directory or from mic/mpssd directory:
Run make -C samples/mic/mpssd or cd samples/mic/mpssd; make
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>