Date: Mon, 1 Oct 2001 13:04:55 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: freebsd-net@freebsd.org Subject: review of minor clarifying comments Message-ID: <Pine.BSF.4.21.0110011302130.99893-100000@beppo>
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This bit me in the butt yet again about FreeBSD and some assumptions about how
a NIC's softc is laid out- I don't really it stated elsewhere, so a couple
source file comments seem in order.. Frankly, this kind of assumption is
dangerous and unnecessary with methods, but at the very least it ought to be
commented, no?
-matt
Index: net/if_var.h
===================================================================
RCS file: /home/ncvs/src/sys/net/if_var.h,v
retrieving revision 1.37
diff -u -r1.37 if_var.h
--- net/if_var.h 2001/09/18 17:41:42 1.37
+++ net/if_var.h 2001/10/01 20:00:08
@@ -105,6 +105,11 @@
*
* (Would like to call this struct ``if'', but C isn't PL/1.)
*/
+
+/*
+ * NB: For FreeBSD, it is assumed that each NIC driver's softc starts with
+ * one of these structures, typically held within an arpcom structure.
+ */
struct ifnet {
void *if_softc; /* pointer to driver state */
char *if_name; /* name, e.g. ``en'' or ``lo'' */
Index: dev/mii/mii.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/mii/mii.c,v
retrieving revision 1.9
diff -u -r1.9 mii.c
--- dev/mii/mii.c 2001/09/29 18:40:06 1.9
+++ dev/mii/mii.c 2001/10/01 20:00:09
@@ -167,6 +167,9 @@
struct mii_data *mii;
mii = device_get_softc(dev);
+ /*
+ * Note that each NIC's softc must start with an ifnet structure.
+ */
mii->mii_ifp = device_get_softc(device_get_parent(dev));
v = device_get_ivars(dev);
ifmedia_upd = v[0];
@@ -233,6 +236,9 @@
MIIBUS_LINKCHG(parent);
mii = device_get_softc(dev);
+ /*
+ * Note that each NIC's softc must start with an ifnet structure.
+ */
ifp = device_get_softc(parent);
if (mii->mii_media_status & IFM_AVALID) {
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