1 files changed, 9 insertions, 0 deletions
diff --git a/run-command.c b/run-command.c
index 615b6e9c9c..df1edd963f 100644
--- a/run-command.c
+++ b/run-command.c
@@ -537,6 +537,15 @@ fail_pipe:
 	prepare_cmd(&argv, cmd);
 	childenv = prep_childenv(cmd->env);
 
+	/*
+	 * NOTE: In order to prevent deadlocking when using threads special
+	 * care should be taken with the function calls made in between the
+	 * fork() and exec() calls.  No calls should be made to functions which
+	 * require acquiring a lock (e.g. malloc) as the lock could have been
+	 * held by another thread at the time of forking, causing the lock to
+	 * never be released in the child process.  This means only
+	 * Async-Signal-Safe functions are permitted in the child.
+	 */
 	cmd->pid = fork();
 	failed_errno = errno;
 	if (!cmd->pid) {