Put giant locks due to make getaddrinfo(), getnameinfo()

and getipnodeby*() thread-safe.
Our res_*() is not thread-safe.  So, we share lock between
getaddrinfo() and getipnodeby*().  Still, we cannot use
getaddrinfo() and getipnodeby*() in conjunction with other
functions which call res_*().

Requested by:	many people

1 files changed, 22 insertions, 1 deletions

diff --git a/lib/libc/net/getaddrinfo.c b/lib/libc/net/getaddrinfo.c
index 847f162..92c85e8 100644
--- a/lib/libc/net/getaddrinfo.c
+++ b/lib/libc/net/getaddrinfo.c
@@ -274,6 +274,21 @@ static char *ai_errlist[] = {
 	"Unknown error", 				/* EAI_MAX        */
 };
 
+/* Make getaddrinfo() thread-safe in libc for use with kernel threads. */
+#include "libc_private.h"
+#include "spinlock.h"
+/*
+ * XXX: Our res_*() is not thread-safe.  So, we share lock between
+ * getaddrinfo() and getipnodeby*().  Still, we cannot use
+ * getaddrinfo() and getipnodeby*() in conjunction with other
+ * functions which call res_*().
+ */
+spinlock_t __getaddrinfo_thread_lock = _SPINLOCK_INITIALIZER;
+#define THREAD_LOCK() \
+	if (__isthreaded) _SPINLOCK(&__getaddrinfo_thread_lock);
+#define THREAD_UNLOCK() \
+	if (__isthreaded) _SPINUNLOCK(&__getaddrinfo_thread_lock);
+
 /* XXX macros that make external reference is BAD. */
 
 #define	GET_AI(ai, afd, addr) \
@@ -599,11 +614,15 @@ explore_fqdn(pai, hostname, servname, res)
 
 	result = NULL;
 
+	THREAD_LOCK();
+
 	/*
 	 * if the servname does not match socktype/protocol, ignore it.
 	 */
-	if (get_portmatch(pai, servname) != 0)
+	if (get_portmatch(pai, servname) != 0) {
+		THREAD_UNLOCK();
 		return 0;
+	}
 
 	switch (nsdispatch(&result, dtab, NSDB_HOSTS, "getaddrinfo",
 			default_dns_files, hostname, pai)) {
@@ -624,12 +643,14 @@ explore_fqdn(pai, hostname, servname, res)
 		}
 		break;
 	}
+	THREAD_UNLOCK();
 
 	*res = result;
 
 	return 0;
 
 free:
+	THREAD_UNLOCK();
 	if (result)
 		freeaddrinfo(result);
 	return error;