From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] netdevsim: remove incorrect __net_initdata annotations Date: Wed, 04 Apr 2018 12:54:08 -0400 (EDT) Message-ID: <20180404.125408.177932788493384392.davem@davemloft.net> References: <20180404121347.3089169-1-arnd@arndb.de> <20180404.115215.419039708931754897.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: jakub.kicinski@netronome.com, dsa@cumulusnetworks.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: arnd@arndb.de Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Arnd Bergmann Date: Wed, 4 Apr 2018 18:03:41 +0200 > On Wed, Apr 4, 2018 at 5:52 PM, David Miller wrote: >> From: Arnd Bergmann >> Date: Wed, 4 Apr 2018 14:12:39 +0200 >> >>> The __net_initdata section cannot currently be used for structures that >>> get cleaned up in an exitcall using unregister_pernet_operations: >>> >>> WARNING: vmlinux.o(.text+0x868c34): Section mismatch in reference from the function nsim_devlink_exit() to the (unknown reference) .init.data:(unknown) >>> The function nsim_devlink_exit() references >>> the (unknown reference) __initdata (unknown). >>> This is often because nsim_devlink_exit lacks a __initdata >>> annotation or the annotation of (unknown) is wrong. >>> WARNING: vmlinux.o(.text+0x868c64): Section mismatch in reference from the function nsim_devlink_init() to the (unknown reference) .init.data:(unknown) >>> WARNING: vmlinux.o(.text+0x8692bc): Section mismatch in reference from the function nsim_fib_exit() to the (unknown reference) .init.data:(unknown) >>> WARNING: vmlinux.o(.text+0x869300): Section mismatch in reference from the function nsim_fib_init() to the (unknown reference) .init.data:(unknown) >>> >>> As that warning tells us, discarding the structure after a module is >>> loaded would lead to a undefined behavior when that module is removed. >>> >>> It might be possible to change that annotation so it has no effect for >>> loadable modules, but I have not figured out exactly how to do that, and >>> we want this to be fixed in -rc1. >>> >>> This just removes the annotations, just like we do for all other such >>> modules. >>> >>> Fixes: 37923ed6b8ce ("netdevsim: Add simple FIB resource controller via devlink") >>> Signed-off-by: Arnd Bergmann >> >> Hmmm... >> >> __net_initdata defines to nothing if network namespaces are enabled. >> >> That's the whole point. >> >> Therefore, if NETNS is disabled, "unregister_pernet_operations" cannot >> happen and this is the only time when __net_initdata actually does >> something. > > The problem happens with CONFIG_NETNS=n: __net_initdata turns into > __initdata, and nsim_fib_net_ops is referenced from a function that is > not marked __init (i.e. nsim_fib_exit). > > The logic to turn __net_initdata into __init only makes sense for > subsystems that have no way to be unregistered, i.e. code which is > always built-in, or non-unloadable modules. Ok, I see it. I'll apply this for now, thanks.