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authorriastradh <riastradh@NetBSD.org>2021-06-16 00:21:17 +0000
committerriastradh <riastradh@NetBSD.org>2021-06-16 00:21:17 +0000
commitbbdda93be2f0bfefe91466b398fe42700a6ea284 (patch)
treee75e77046575209dbb21f73d0bc44c61ec0ec6c0 /sys/net/if_l2tp.c
parent5a96957fa793651c8e7093a5a4c2fcae87232af2 (diff)
if_attach and if_initialize cannot fail, don't test return value
These were originally made failable back in 2017 when if_initialize allocated a softint in every interface for link state changes, so that it could fail gracefully instead of panicking: https://mail-index.NetBSD.org/source-changes/2017/10/23/msg089053.html However, this spawned many seldom- or never-tested error branches, which are risky to have around. And that softint in every interface has since been replaced by a single global workqueue, because link state changes require thread context but not low latency or high throughput: https://mail-index.NetBSD.org/source-changes/2020/02/06/msg113759.html So there is no longer any reason for if_initialize to fail. (The subroutine if_stats_init can't fail because percpu_alloc can't fail either.) There is a snag: the softint_establish in if_percpuq_create could fail, potentially leading to bad consequences later on trying to use the softint. This change doesn't introduce any new bugs because of the snag -- if_percpuq_attach was already broken. However, the snag can be better addressed without spawning error branches, either by using a single softint or making softints less scarce. (Separate commit will change the signatures of if_attach and if_initialize to return void, scheduled to ride whatever is the next convenient kernel bump.) Patch and testing on amd64 and evbmips64-eb by maya@; commit message soliloquy, and compile-testing on evbppc/i386/earmv7hf, by me.
Diffstat (limited to 'sys/net/if_l2tp.c')
-rw-r--r--sys/net/if_l2tp.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/sys/net/if_l2tp.c b/sys/net/if_l2tp.c
index aa3c10be429..af2ce9baec4 100644
--- a/sys/net/if_l2tp.c
+++ b/sys/net/if_l2tp.c
@@ -1,4 +1,4 @@
-/* $NetBSD: if_l2tp.c,v 1.46 2020/10/25 08:18:39 roy Exp $ */
+/* $NetBSD: if_l2tp.c,v 1.47 2021/06/16 00:21:19 riastradh Exp $ */
/*
* Copyright (c) 2017 Internet Initiative Japan Inc.
@@ -31,7 +31,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_l2tp.c,v 1.46 2020/10/25 08:18:39 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_l2tp.c,v 1.47 2021/06/16 00:21:19 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_inet.h"
@@ -281,7 +281,6 @@ l2tp_clone_create(struct if_clone *ifc, int unit)
int
l2tpattach0(struct l2tp_softc *sc)
{
- int rv;
sc->l2tp_ec.ec_if.if_addrlen = 0;
sc->l2tp_ec.ec_if.if_mtu = L2TP_MTU;
@@ -321,9 +320,7 @@ l2tpattach0(struct l2tp_softc *sc)
* if_percpuq_enqueue(). However, that causes recursive softnet_lock
* when NET_MPSAFE is not set.
*/
- rv = if_attach(&sc->l2tp_ec.ec_if);
- if (rv != 0)
- return rv;
+ if_attach(&sc->l2tp_ec.ec_if);
if_link_state_change(&sc->l2tp_ec.ec_if, LINK_STATE_DOWN);
if_alloc_sadl(&sc->l2tp_ec.ec_if);
bpf_attach(&sc->l2tp_ec.ec_if, DLT_EN10MB, sizeof(struct ether_header));