When gcc atomic intrinsics are not available (such as on RHEL 5
with gcc 4.1.2), we were getting link errors due to multiple
definitions:
./.libs/libvirt_util.a(libvirt_util_la-virobject.o): In function `virAtomicIntXor':
/home/dummy/l,ibvirt/src/util/viratomoic.h:404: multiple definition of `virAtomicIntXor'
./.libs/libvirt_util.a(libvirt_util_la-viratomic.o):/home/dummy/libvirt/src/util/viratomic.h:404: first defined here
Solve this by conditionally marking the functions static (the
condition avoids falling foul of gcc warnings about unused
static function declarations).
* src/util/viratomic.h: When not using gcc intrinsics, use static
functions to avoid linker errors on duplicate functions.
There are a few issues with the current virAtomic APIs
- They require use of a virAtomicInt struct instead of a plain
int type
- Several of the methods do not implement memory barriers
- The methods do not implement compiler re-ordering barriers
- There is no Win32 native impl
The GLib library has a nice LGPLv2+ licensed impl of atomic
ops that works with GCC, Win32, or pthreads.h that addresses
all these problems. The main downside to their code is that
the pthreads impl uses a single global mutex, instead of
a per-variable mutex. Given that it does have a Win32 impl
though, we don't expect anyone to seriously use the pthread.h
impl, so this downside is not significant.
* .gitignore: Ignore test case
* configure.ac: Check for which atomic ops impl to use
* src/Makefile.am: Add viratomic.c
* src/nwfilter/nwfilter_dhcpsnoop.c: Switch to new atomic
ops APIs and plain int datatype
* src/util/viratomic.h: inline impls of all atomic ops
for GCC, Win32 and pthreads
* src/util/viratomic.c: Global pthreads mutex for atomic
ops
* tests/viratomictest.c: Test validate to validate safety
of atomic ops.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Per the FSF address could be changed from time to time, and GNU
recommends the following now: (http://www.gnu.org/licenses/gpl-howto.html)
You should have received a copy of the GNU General Public License
along with Foobar. If not, see <http://www.gnu.org/licenses/>.
This patch removes the explicit FSF address, and uses above instead
(of course, with inserting 'Lesser' before 'General').
Except a bunch of files for security driver, all others are changed
automatically, the copyright for securify files are not complete,
that's why to do it manually:
src/security/security_selinux.h
src/security/security_driver.h
src/security/security_selinux.c
src/security/security_apparmor.h
src/security/security_apparmor.c
src/security/security_driver.c
This patch improves the previously added virAtomicInt implementation
by using gcc-builtins if possible. The needed builtins are available
since GCC >= 4.1. At least the 4.0 docs don't mention them.
