None of the atomic implementations need a destroy function anymore, so it's
"more standard" and more convenient for users to get rid of them.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>
Every implementation used this same code, so it makes sense to centralize
it.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>
Until now, the GCC 4+ and pthreads implementations of atomics have used
struct wrappers for their atomic types. This had the advantage of allowing
a mutex to be wrapped in, in some cases, and of better type-checking by
preventing stray uses of atomic variables other than through one of the
atomic_*() functions or macros. However, the mutex meant that an
atomic_destroy() function-like macro needed to be used. The struct wrapper
also made it impossible to define new atomic types that were compatible
with each other without using a typedef. For example, one could not simply
define a macro like
#define ATOMIC(TYPE) struct { TYPE value; }
and then have two declarations like:
ATOMIC(void *) x;
ATOMIC(void *) y;
and do anything with these objects that require type-compatibility, even
"&x == &y", because the two structs are not compatible. One can do it
through a typedef:
typedef ATOMIC(void *) atomic_voidp;
atomic_voidp x, y;
but that is inconvenient, especially because of the need to invent a name
for the type.
This commit aims to ease the problem by getting rid of the wrapper structs
in the cases where the atomic library used them. It gets rid of the
mutexes, in the cases where they are still needed, by using a global
array of mutexes instead.
This commit also defines the ATOMIC macro described above and documents
its use in ovs-atomic.h.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>
Standard C11 doesn't need these functions because it is able to require
implementations not to need them. But we can't construct a portable
implementation that does not need them in every case, so this commit adds
them.
These functions are only needed for atomic_flag objects that are
dynamically allocated (because statically allocated objects can use
ATOMIC_FLAG_INIT). So far there aren't any of those, but an upcoming
commit will introduce one.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
Commit 97be153858 (clang: Add
annotations for thread safety check.) defined 'struct ovs_mutex'
variable in 'atomic_flag' in 'ovs-atomic-pthreads.h'. This
casued "mutex: has incomplete type" error in compilation when
'ovs-atomic-pthreads.h' is included.
This commit goes back to use 'pthread_mutex_t' for that variable
and adds test for the 'atomic_flag' related functions.
Reported-by: Gurucharan Shetty <gshetty@nicira.com>
Signed-off-by: Alex Wang <alexw@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit adds annotations for thread safety check. And the
check can be conducted by using -Wthread-safety flag in clang.
Co-authored-by: Alex Wang <alexw@nicira.com>
Signed-off-by: Alex Wang <alexw@nicira.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
This library should prove useful for the threading changes coming up.
The following commit introduces one (very simple) user.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
