From ad8f078f66e51212cdccd91fe8b22fb81235018e Mon Sep 17 00:00:00 2001 From: Hans Petter Selasky Date: Tue, 9 Nov 2021 22:07:43 +0100 Subject: [PATCH] ifconfig(8): Don't set network interface capabilities when there is no change. A quick grep through the kernel code shows network drivers compute the changed bits of network capabilities after a SIOCSIFCAP IOCTL(2) by using the bitwise exclusive or operation. When the set capabilities are equal to the already read capabilities, no action will be taken. Let ifconfig(8) predict this case and skip the SIOCSIFCAP IOCTL(2) system call. Discussed with: kib@ (revert change in case of issues) MFC after: 1 week Sponsored by: NVIDIA Networking --- sbin/ifconfig/ifconfig.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c index 0423b3593504..9e7d38d4c2a4 100644 --- a/sbin/ifconfig/ifconfig.c +++ b/sbin/ifconfig/ifconfig.c @@ -1243,6 +1243,9 @@ setifcap(const char *vname, int value, int s, const struct afswtch *afp) } else flags |= value; flags &= ifr.ifr_reqcap; + /* Check for no change in capabilities. */ + if (ifr.ifr_curcap == flags) + return; ifr.ifr_reqcap = flags; if (ioctl(s, SIOCSIFCAP, (caddr_t)&ifr) < 0) Perror(vname);