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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_loop.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These were originally made failable back in 2017 when if_initialize allocated a softint in every interface for link state changes, so that it could fail gracefully instead of panicking: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 And that softint in every interface has since been replaced by a single global workqueue, because link state changes require thread context but not low latency or high throughput: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_loop.c')
-rw-r--r--sys/net/if_loop.c11
1 files changed, 3 insertions, 8 deletions
diff --git a/sys/net/if_loop.c b/sys/net/if_loop.c
index 6e4c8dcf484..ff2a401d53a 100644
--- a/sys/net/if_loop.c
+++ b/sys/net/if_loop.c
@@ -1,4 +1,4 @@
-/* $NetBSD: if_loop.c,v 1.112 2020/10/14 16:10:32 roy Exp $ */
+/* $NetBSD: if_loop.c,v 1.113 2021/06/16 00:21:19 riastradh Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -65,7 +65,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_loop.c,v 1.112 2020/10/14 16:10:32 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_loop.c,v 1.113 2021/06/16 00:21:19 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_inet.h"
@@ -175,7 +175,6 @@ static int
loop_clone_create(struct if_clone *ifc, int unit)
{
struct ifnet *ifp;
- int rv;
ifp = if_alloc(IFT_LOOP);
@@ -198,11 +197,7 @@ loop_clone_create(struct if_clone *ifc, int unit)
IFQ_SET_READY(&ifp->if_snd);
if (unit == 0)
lo0ifp = ifp;
- rv = if_initialize(ifp);
- if (rv != 0) {
- if_free(ifp);
- return rv;
- }
+ if_initialize(ifp);
ifp->if_link_state = LINK_STATE_UP;
if_alloc_sadl(ifp);
bpf_attach(ifp, DLT_NULL, sizeof(u_int));