lock.c: Add AMI event for deadlocks.

Adds an AMI event to indicate that a deadlock
has likely started, when Asterisk is compiled
with DETECT_DEADLOCKS enabled. This can make
it easier to perform automated deadlock detection
and take appropriate action (such as doing a core
dump). Unlike the deadlock warnings, the AMI event
is emitted only once per deadlock.

ASTERISK-30161 #close

Change-Id: Ifc6ed3e390f8b4cff7f8077a50e4d7a5b54e42fb

diff --git a/doc/CHANGES-staging/lock_deadlock.txt b/doc/CHANGES-staging/lock_deadlock.txt
new file mode 100644 (file)
index 0000000..5fad3ee
--- /dev/null
+++ b/doc/CHANGES-staging/lock_deadlock.txt
@@ -0,0 +1,5 @@
+Subject: locks
+
+A new AMI event, DeadlockStart, is now available
+when Asterisk is compiled with DETECT_DEADLOCKS,
+and can indicate that a deadlock has occured.

diff --git a/main/lock.c b/main/lock.c
index fcf0839f405a3ef76ff492586cc53856679b38eb..8d09f00520cd53c2ed79cca6a5f343691a03df76 100644 (file)
--- a/main/lock.c
+++ b/main/lock.c
@@ -38,6 +38,7 @@ static void __attribute__((constructor)) __mtx_init(void)
 
 #include "asterisk/utils.h"
 #include "asterisk/lock.h"
+#include "asterisk/manager.h"
 
 /* Allow direct use of pthread_mutex_* / pthread_cond_* */
 #undef pthread_mutex_init
@@ -311,6 +312,26 @@ int __ast_pthread_mutex_lock(const char *filename, int lineno, const char *func,
                                                ast_reentrancy_unlock(lt);
                                        }
                                        reported_wait = wait_time;
+                                       if ((int) wait_time < 10) { /* Only emit an event when a deadlock starts, not every 5 seconds */
+                                               /*** DOCUMENTATION
+                                                       <managerEvent language="en_US" name="DeadlockStart">
+                                                               <managerEventInstance class="EVENT_FLAG_SYSTEM">
+                                                                       <synopsis>Raised when a probable deadlock has started.
+                                                                       Delivery of this event is attempted but not guaranteed,
+                                                                        and could fail for example if the manager itself is deadlocked.
+                                                                        </synopsis>
+                                                                               <syntax>
+                                                                                       <parameter name="Mutex">
+                                                                                               <para>The mutex involved in the deadlock.</para>
+                                                                                       </parameter>
+                                                                               </syntax>
+                                                               </managerEventInstance>
+                                                       </managerEvent>
+                                               ***/
+                                               manager_event(EVENT_FLAG_SYSTEM, "DeadlockStart",
+                                                       "Mutex: %s\r\n",
+                                                       mutex_name);
+                                       }
                                }
                                usleep(200);
                        }