3 files changed, 12 insertions, 2 deletions
diff --git a/os/common/oslib/include/chmempools.h b/os/common/oslib/include/chmempools.h
index 5c7666f4e..e2bd4277e 100644
--- a/os/common/oslib/include/chmempools.h
+++ b/os/common/oslib/include/chmempools.h
@@ -304,8 +304,15 @@ static inline void chGuardedPoolAddI(guarded_memory_pool_t *gmp, void *objp) {
  * @iclass
  */
 static inline void *chGuardedPoolAllocI(guarded_memory_pool_t *gmp) {
-
-  return chPoolAllocI(&gmp->pool);
+  void *p;
+
+  p = chPoolAllocI(&gmp->pool);
+  if (p != NULL) {
+    chSemFastWaitI(&gmp->sem);
+    chDbgAssert(chSemGetCounterI(&gmp->sem) >= (cnt_t)0,
+                "semaphore out of sync");
+  }
+  return p;
 }
 #endif /* CH_CFG_USE_SEMAPHORES == TRUE */
 
diff --git a/readme.txt b/readme.txt
index fa5e5b1fb..fa1a6cf1a 100644
--- a/readme.txt
+++ b/readme.txt
@@ -166,6 +166,8 @@
        dependencies and configuration directories. This makes possible
        to have multiple non-conflicting makefiles in the same project.
        Updated the various platform.mk implementing "smart build" mode.
+- LIB: Fixed inner semaphore not updated in chGuardedPoolAllocI() function
+       (bug #911).
 - HAL: Fixed chprintf float support for 0 precision (bug #910)(backported to
        17.6.4 and 16.1.10).
 - RT:  Fixed compile error with assertions enabled and dynamic extensions
diff --git a/release_note_next.txt b/release_note_next.txt
index 6b402943f..2dc4cb2d9 100644
--- a/release_note_next.txt
+++ b/release_note_next.txt
@@ -45,6 +45,7 @@ received a series of important improvements, new features have been added.
   exchange complex objects between threads/ISRs. It is based on a
   mailbox and a guarded memory pool.
 - Added alignment handling to memory pools.
+- Added a new chGuardedPoolAllocI() API to the guarded memory pools.
 
 *** What's new in RT 5.0.0 ***