linux/samples
Mark Rutland 94bbc9c1a0 locking/atomics, samples/mic/mpssd/mpssd.c: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_ONCE()
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 ea9156fb3b).

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>
2017-10-25 11:01:01 +02:00
..
auxdisplay samples: move auxdisplay example code from Documentation 2016-09-23 11:52:32 -06:00
blackfin samples: move blackfin gptimers-example from Documentation 2016-10-10 07:12:02 -06:00
bpf bpf: Add lru_hash_lookup performance test 2017-09-01 09:57:38 -07:00
configfs configfs: remove old API 2015-10-13 22:17:57 -07:00
connector make use of make variable CURDIR instead of calling pwd 2016-12-11 12:12:56 +01:00
hidraw HID: samples/hidraw: make it possible to select device 2015-03-15 10:11:21 -04:00
hw_breakpoint
kdb
kfifo kfifo: clean up example to not use page_link 2017-07-12 16:26:01 -07:00
kobject samples/kobject: be explicit in the module license 2015-03-25 13:41:42 +01:00
kprobes samples/kretprobe: fix the wrong type 2016-08-04 08:50:07 -04:00
livepatch livepatch: allow removal of a disabled patch 2017-03-08 09:38:43 +01:00
mei mei: drop the TODO from samples 2017-04-26 11:38:56 +02:00
mic/mpssd locking/atomics, samples/mic/mpssd/mpssd.c: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_ONCE() 2017-10-25 11:01:01 +02:00
pktgen pktgen: Specify the index of first thread 2017-06-16 12:32:34 -04:00
rpmsg rpmsg: Allow callback to return errors 2016-09-08 22:15:25 -07:00
seccomp samples/seccomp: fix 64-bit comparison macros 2017-01-09 17:22:03 +11:00
sockmap bpf: avoid preempt enable/disable in sockmap using tcp_skb_cb region 2017-10-20 13:01:29 +01:00
statx statx: Include a mask for stx_attributes in struct statx 2017-04-03 01:06:00 -04:00
timers samples: move timers example code from Documentation 2016-09-23 11:51:58 -06:00
trace_events tracing/samples: Fix creation and deletion of simple_thread_fn creation 2017-10-17 14:55:24 -04:00
trace_printk tracing: Add trace_printk sample code 2016-06-20 09:54:21 -04:00
uhid HID: uhid: improve uhid example client 2013-09-04 11:35:14 +02:00
v4l media: v4l2-pci-skeleton: constify vb2_ops structures 2017-08-20 08:03:09 -04:00
vfio-mdev vfio-mdev: remove some dead code 2017-01-11 12:12:37 -07:00
watchdog samples: move watchdog example code from Documentation 2016-09-23 11:52:14 -06:00
Kconfig statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00
Makefile statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00