[master] 5604bdaa6 Add a hint in the accept_filter documentation

[Dridi Boukelmoune]

commit 5604bdaa6730d4372a7308746ef4b5cf9ca4d073
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Tue Dec 31 09:14:26 2019 +0100

    Add a hint in the accept_filter documentation
    
    Trying to understand why I was seeing setsockopt fail on FreeBSD VTEST
    boxes and why it failed with an undocumented ENOENT I finally realized
    that I needed to kldload accf_http beforehand.
    
    The ENOENT errno was probably a result of accept_filter code not finding
    a kernel module for "httpready".

diff --git a/include/tbl/params.h b/include/tbl/params.h
index 272829a10..61fa9a03a 100644
--- a/include/tbl/params.h
+++ b/include/tbl/params.h
@@ -48,7 +48,8 @@ PARAM(
 	/* units */	"bool",
 	/* flags */	XYZZY,
 	/* s-text */
-	"Enable kernel accept-filters.",
+	"Enable kernel accept-filters. This may require a kernel module to "
+	"be loaded to have an effect when enabled.",
 	/* l-text */	NULL,
 	/* func */	NULL
 )
diff --git a/lib/libvarnish/vtcp.c b/lib/libvarnish/vtcp.c
index a7ed8f4f9..763db1ee6 100644
--- a/lib/libvarnish/vtcp.c
+++ b/lib/libvarnish/vtcp.c
@@ -153,7 +153,6 @@ VTCP_filter_http(int sock)
 
 	memset(&afa, 0, sizeof afa);
 	bprintf(afa.af_name, "%s", "httpready");
-	errno = 0;
 	retval = setsockopt(sock, SOL_SOCKET, SO_ACCEPTFILTER,
 	    &afa, sizeof afa);
 	return (retval);