]> git.karo-electronics.de Git - karo-tx-linux.git/commit
h8300: select generic atomic64_t support
authorFengguang Wu <fengguang.wu@intel.com>
Thu, 13 Sep 2012 00:58:21 +0000 (10:58 +1000)
committerStephen Rothwell <sfr@canb.auug.org.au>
Thu, 20 Sep 2012 07:04:48 +0000 (17:04 +1000)
commit90262046a2e8c068a16de4275db45d779f25c08a
treed4ec83b375bcc4621d687782da692ee2be40fa6d
parent976346636f97179cfaa02d8067ba84169cbf01da
h8300: select generic atomic64_t support

Rationales from Eric:

So I just looked a little deeper and it appears architectures that do
not support atomic64_t are broken.

The generic atomic64 support came in 2009 to support the perf subsystem
with the expectation that all architectures would implement atomic64
support.

Furthermore upon inspection of the kernel atomic64_t is used in a fair
number of places beyond the performance counters:

block/blk-cgroup.c
drivers/acpi/apei/
drivers/block/rbd.c
drivers/crypto/nx/nx.h
drivers/gpu/drm/radeon/radeon.h
drivers/infiniband/hw/ipath/
drivers/infiniband/hw/qib/
drivers/staging/octeon/
fs/xfs/
include/linux/perf_event.h
include/net/netfilter/nf_conntrack_acct.h
kernel/events/
kernel/trace/
net/mac80211/key.h
net/rds/

The block control group, infiniband, xfs, crypto, 802.11, netfilter.
Nothing quite so fundamental as fs/namespace.c but definitely in
multiplatform-code that should work, and is already broken on those
architecutres.

Looking at the implementation of atomic64_add_return in lib/atomic64.c the
code looks as efficient as these kinds of things get.

Which leads me to the conclusion that we need atomic64 support on all
architectures.

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
arch/h8300/Kconfig