From b6b35d80755caed0528dfdf3825ecf055fe9ea76 Mon Sep 17 00:00:00 2001
From: Roman Rashchupkin <rrashchupkin@cloudlinux.com>
Date: Wed, 28 Feb 2018 23:05:50 +0300
Subject: [PATCH 16/89] Waitpid for finished threads after detach.

---
 src/kpatch_process.c | 14 +++++++++++++-
 src/kpatch_ptrace.c  |  2 +-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/kpatch_process.c b/src/kpatch_process.c
index 2f85373..5c0374a 100644
--- a/src/kpatch_process.c
+++ b/src/kpatch_process.c
@@ -12,6 +12,11 @@
 #include <sys/stat.h>
 #include <sys/sysmacros.h>
 
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/ptrace.h>
+
 #include <gelf.h>
 #include <libunwind.h>
 #include <libunwind-ptrace.h>
@@ -537,6 +542,8 @@ static void
 process_detach(kpatch_process_t *proc)
 {
 	struct kpatch_ptrace_ctx *p, *ptmp;
+	int status;
+	pid_t pid;
 
 	if (proc->memfd >= 0 && close(proc->memfd) < 0)
 		kplogerror("can't close memfd");
@@ -546,9 +553,14 @@ process_detach(kpatch_process_t *proc)
 		unw_destroy_addr_space(proc->ptrace.unwd);
 
 	list_for_each_entry_safe(p, ptmp, &proc->ptrace.pctxs, list) {
-		kpatch_ptrace_detach(p);
+		if (kpatch_ptrace_detach(p) == -ESRCH) {
+			do {
+				pid = waitpid(p->pid, &status, __WALL);
+			} while (pid > 0 && !WIFEXITED(status));
+		}
 		kpatch_ptrace_ctx_destroy(p);
 	}
+	kpinfo("Finished ptrace detaching.");
 }
 
 static int
diff --git a/src/kpatch_ptrace.c b/src/kpatch_ptrace.c
index f91b80e..a5f61b3 100644
--- a/src/kpatch_ptrace.c
+++ b/src/kpatch_ptrace.c
@@ -1186,7 +1186,7 @@ int kpatch_ptrace_detach(struct kpatch_ptrace_ctx *pctx)
 	ret = ptrace(PTRACE_DETACH, pctx->pid, NULL, NULL);
 	if (ret < 0) {
 		kplogerror("can't detach from %d\n", pctx->pid);
-		return -1;
+		return -errno;
 	}
 
 	kpdebug("OK\n");
-- 
2.23.0