git: ad8f078f66e5 - main - ifconfig(8): Don't set network interface capabilities when there is no change.

The branch main has been updated by hselasky:

URL: https://cgit.FreeBSD.org/src/commit/?id=ad8f078f66e51212cdccd91fe8b22fb81235018e

commit ad8f078f66e51212cdccd91fe8b22fb81235018e
Author:     Hans Petter Selasky <hselasky@FreeBSD.org>
AuthorDate: 2021-11-09 21:07:43 +0000
Commit:     Hans Petter Selasky <hselasky@FreeBSD.org>
CommitDate: 2021-11-10 14:50:52 +0000

    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);