vppinfra: Expose function setting __os_thread_index

Type: feature

This is needed when creating pthreads in client applications,
they need a way to set __os_thread_index per thread
that does not conflict with the binary API thread index.

If __os_thread_index is left to 0 in two client pthreads and
they call vl_msg_api_alloc and vec_resize at the same time
it can fail due to them sharing (and push/poping) the same
clib_per_cpu_mheaps slot.

Change-Id: I85d4248a39b641a4d3ad5a1c1bd6e0db5875fab6
Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>

2 files changed, 27 insertions, 0 deletions

diff --git a/src/vppinfra/mem.h b/src/vppinfra/mem.h
index e31ec82e7c5..f2930a11253 100644
--- a/src/vppinfra/mem.h
+++ b/src/vppinfra/mem.h
@@ -60,6 +60,27 @@
 /* Per CPU heaps. */
 extern void *clib_per_cpu_mheaps[CLIB_MAX_MHEAPS];
 
+always_inline void
+clib_mem_set_thread_index (void)
+{
+  /*
+   * Find an unused slot in the per-cpu-mheaps array,
+   * and grab it for this thread. We need to be able to
+   * push/pop the thread heap without affecting other thread(s).
+   */
+  int i;
+  if (__os_thread_index != 0)
+    return;
+  for (i = 0; i < ARRAY_LEN (clib_per_cpu_mheaps); i++)
+    if (clib_atomic_bool_cmp_and_swap (&clib_per_cpu_mheaps[i],
+				       0, clib_per_cpu_mheaps[0]))
+      {
+	os_set_thread_index (i);
+	break;
+      }
+  ASSERT (__os_thread_index > 0);
+}
+
 always_inline void *
 clib_mem_get_per_cpu_heap (void)
 {
diff --git a/src/vppinfra/os.h b/src/vppinfra/os.h
index 3ec214e29b1..50a4ad97c93 100644
--- a/src/vppinfra/os.h
+++ b/src/vppinfra/os.h
@@ -64,6 +64,12 @@ os_get_thread_index (void)
   return __os_thread_index;
 }
 
+static_always_inline void
+os_set_thread_index (uword thread_index)
+{
+  __os_thread_index = thread_index;
+}
+
 static_always_inline uword
 os_get_cpu_number (void) __attribute__ ((deprecated));