From: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>,
David Lin <dtwlin@google.com>,
"Anton V. Boyarshinov" <boyarsh@altlinux.org>,
"Dmitry V. Levin" <ldv@altlinux.org>,
Michal Marek <mmarek@suse.com>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] jump label: fix passing kbuild_cflags when checking for asm goto support
Date: Fri, 10 Mar 2017 20:39:52 +0300 [thread overview]
Message-ID: <20170310173952.GW27556@glebfm.cloud.tilaa.com> (raw)
In-Reply-To: <20170310120422.14e19269@gandalf.local.home>
On Fri, Mar 10, 2017 at 12:04:22PM -0500, Steven Rostedt wrote:
> On Fri, 10 Mar 2017 19:24:18 +0300
> Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org> wrote:
>
> > The latest change of asm goto support check added passing of
> > KBUILD_CFLAGS to compiler. When these flags reference gcc plugins,
> > there is a race condition between the build of these plugins and their
> > use in this asm goto support check.
> >
> > This change moves the check before all these references are added
> > to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS
> > modifications are not relevant to this check.
>
> What exactly breaks when the race happens?
Actually, this is not quite a race. When you run "make bzImage" followed
by "make modules", the kernel is always built with HAVE_JUMP_LABEL
disabled, while the modules are built depending on CONFIG_JUMP_LABEL.
If HAVE_JUMP_LABEL macro happens to be different, modules are built
with undefined references:
ERROR: "static_key_slow_inc" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/nft_meta.ko] undefined!
ERROR: "static_key_slow_inc" [net/netfilter/nft_meta.ko] undefined!
ERROR: "nf_hooks_needed" [net/netfilter/ipvs/ip_vs.ko] undefined!
ERROR: "nf_hooks_needed" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_count" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_slow_inc" [net/ipv6/ipv6.ko] undefined!
ERROR: "nf_hooks_needed" [net/decnet/decnet.ko] undefined!
--
glebfm
next prev parent reply other threads:[~2017-03-10 17:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-10 16:24 [PATCH] jump label: fix passing kbuild_cflags when checking for asm goto support Gleb Fotengauer-Malinovskiy
2017-03-10 17:04 ` Steven Rostedt
2017-03-10 17:39 ` Gleb Fotengauer-Malinovskiy [this message]
2017-03-10 17:42 ` Steven Rostedt
2017-03-10 17:55 ` [PATCH v2] " Gleb Fotengauer-Malinovskiy
2017-03-10 18:04 ` Steven Rostedt
2017-03-10 18:30 ` David Lin
2017-03-20 17:15 ` [PING PATCH " Gleb Fotengauer-Malinovskiy
2017-03-21 17:48 ` Masahiro Yamada
2017-03-21 18:04 ` Steven Rostedt
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