Add smp_mc() to force_mb_single_thread so we don't assume anything from the OS.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

diff --git a/urcu.c b/urcu.c
index 8381f7b6f61bc892cdf25d671d21ef5b05aae9a5..8cbdef9e66b386c0b6ac175b2029e194bfe3b43f 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -92,7 +92,14 @@ static void force_mb_single_thread(pthread_t tid)
 {
        assert(reader_data);
        sig_done = 0;
-       smp_mb();       /* write sig_done before sending the signals */
+       /*
+        * pthread_kill has a smp_mb(). But beware, we assume it performs
+        * a cache flush on architectures with non-coherent cache. Let's play
+        * safe and don't assume anything : we use smp_mc() to make sure the
+        * cache flush is enforced.
+        * smp_mb();    write sig_done before sending the signals
+        */
+       smp_mc();       /* write sig_done before sending the signals */
        pthread_kill(tid, SIGURCU);
        /*
         * Wait for sighandler (and thus mb()) to execute on every thread.
@@ -115,9 +122,12 @@ static void force_mb_all_threads(void)
        sig_done = 0;
        /*
         * pthread_kill has a smp_mb(). But beware, we assume it performs
-        * a cache flush on architectures with non-coherent cache.
+        * a cache flush on architectures with non-coherent cache. Let's play
+        * safe and don't assume anything : we use smp_mc() to make sure the
+        * cache flush is enforced.
         * smp_mb();    write sig_done before sending the signals
         */
+       smp_mc();       /* write sig_done before sending the signals */
        for (index = reader_data; index < reader_data + num_readers; index++)
                pthread_kill(index->tid, SIGURCU);
        /*