From 99159b174eb245a7162fe38900971cdff017cf75 Mon Sep 17 00:00:00 2001
From: Michael Lee <michael-cy.lee@mediatek.com>
Date: Thu, 13 Jul 2023 13:14:26 +0800
Subject: [PATCH] hostapd: mtk: Check the bridge after ioctl SIOCBRADDIF failed

If ioctl returns EBUSY on command SIOCBRADDIF, the interface might
already be bridged by others, and linux_br_add_if should not indicate an
error in the case.

This patch checks whether the interface is correctly brigded when ioctl
returns EBUSY.

Signed-off-by: Michael Lee <michael-cy.lee@mediatek.com>
---
 src/drivers/linux_ioctl.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/drivers/linux_ioctl.c b/src/drivers/linux_ioctl.c
index 7edb9df..b8c1af2 100644
--- a/src/drivers/linux_ioctl.c
+++ b/src/drivers/linux_ioctl.c
@@ -150,7 +150,8 @@ int linux_br_del(int sock, const char *brname)
 int linux_br_add_if(int sock, const char *brname, const char *ifname)
 {
 	struct ifreq ifr;
-	int ifindex;
+	int ifindex, ret;
+	char in_br[IFNAMSIZ];
 
 	ifindex = if_nametoindex(ifname);
 	if (ifindex == 0)
@@ -164,8 +165,19 @@ int linux_br_add_if(int sock, const char *brname, const char *ifname)
 
 		wpa_printf(MSG_DEBUG, "Could not add interface %s into bridge "
 			   "%s: %s", ifname, brname, strerror(errno));
+
+		/* If ioctl returns -EBUSY when adding interface into bridge,
+		 * the interface might already be added by netifd, so here we
+		 * check whether the interface is currently on the right
+		 * bridge. */
+		if(errno == EBUSY && linux_br_get(in_br, ifname) == 0 &&
+	           os_strcmp(in_br, brname) == 0)
+			ret = 0;
+		else
+			ret = -1;
+
 		errno = saved_errno;
-		return -1;
+		return ret;
 	}
 
 	return 0;
-- 
2.25.1