tcp: Print error reported from sys_setsockopt

We use pr_perror, but after direct syscall calling the
errno is not initialized (and in PIE it doesn't even exists).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/sk-inet.h

@@ -51,10 +51,11 @@ struct rst_tcp_sock {
 
 static inline void tcp_repair_off(int fd)
 {
-	int aux = 0;
+	int aux = 0, ret;
 
-	if (sys_setsockopt(fd, SOL_TCP, TCP_REPAIR, &aux, sizeof(aux)) < 0)
-		pr_perror("Failed to turn off repair mode on socket");
+	ret = sys_setsockopt(fd, SOL_TCP, TCP_REPAIR, &aux, sizeof(aux));
+	if (ret < 0)
+		pr_perror("Failed to turn off repair mode on socket (%d)", ret);
 }
 
 void tcp_locked_conn_add(struct inet_sk_info *);

pie/restorer.c

@@ -333,13 +333,15 @@ static u64 restore_mapping(const VmaEntry *vma_entry)
 
 static void rst_tcp_repair_off(struct rst_tcp_sock *rts)
 {
-	int aux;
+	int aux, ret;
 
+	aux = rts->reuseaddr;
+	pr_debug("pie: Turning repair off for %d (reuse %d)\n", rts->sk, aux);
 	tcp_repair_off(rts->sk);
 
-	aux = rts->reuseaddr;
-	if (sys_setsockopt(rts->sk, SOL_SOCKET, SO_REUSEADDR, &aux, sizeof(aux)) < 0)
-		pr_perror("Failed to restore of SO_REUSEADDR on socket");
+	ret = sys_setsockopt(rts->sk, SOL_SOCKET, SO_REUSEADDR, &aux, sizeof(aux));
+	if (ret < 0)
+		pr_perror("Failed to restore of SO_REUSEADDR on socket (%d)", ret);
 }
 
 static void rst_tcp_socks_all(struct rst_tcp_sock *arr, int size)