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Subject: Re: [PATCH net-next 2/2] bonding: combine netlink and console error
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To:     Joe Perches <joe@perches.com>, netdev@vger.kernel.org
Cc:     Jay Vosburgh <j.vosburgh@gmail.com>,
        Veaceslav Falico <vfalico@gmail.com>,
        Andy Gospodarek <andy@greyhouse.net>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, linux-kernel@vger.kernel.org
References: <cover.1628306392.git.jtoppins@redhat.com>
 <a36c7639a13963883f49c272ed7993c9625a712a.1628306392.git.jtoppins@redhat.com>
 <37c7bbbb01ede99974fc9ce3c3f5dad4845df9ee.camel@perches.com>
 <f519f9eb-aefd-4d0a-01ce-4ed37b7930ef@redhat.com>
 <745ab8a85430ad4268a86b0957aa690c1a7a6d0f.camel@perches.com>
From:   Jonathan Toppins <jtoppins@redhat.com>
Message-ID: <b384c564-8467-1504-026c-5a437cad1a14@redhat.com>
Date:   Sun, 8 Aug 2021 22:07:11 -0400
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On 8/8/21 6:02 AM, Joe Perches wrote:
> On Sat, 2021-08-07 at 17:54 -0400, Jonathan Toppins wrote:
>> On 8/6/21 11:52 PM, Joe Perches wrote:
>>> On Fri, 2021-08-06 at 23:30 -0400, Jonathan Toppins wrote:
>>>> There seems to be no reason to have different error messages between
>>>> netlink and printk. It also cleans up the function slightly.
>>> []
>>>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>>> []
>>>> +#define BOND_NL_ERR(bond_dev, extack, errmsg) do {		\
>>>> +	NL_SET_ERR_MSG(extack, errmsg);				\
>>>> +	netdev_err(bond_dev, "Error: " errmsg "\n");		\
>>>> +} while (0)
>>>> +
>>>> +#define SLAVE_NL_ERR(bond_dev, slave_dev, extack, errmsg) do {	\
>>>> +	NL_SET_ERR_MSG(extack, errmsg);				\
>>>> +	slave_err(bond_dev, slave_dev, "Error: " errmsg "\n");	\
>>>> +} while (0)
>>>
>>> If you are doing this, it's probably smaller object code to use
>>> 	"%s", errmsg
>>> as the errmsg string can be reused
>>>
>>> #define BOND_NL_ERR(bond_dev, extack, errmsg)			\
>>> do {								\
>>> 	NL_SET_ERR_MSG(extack, errmsg);				\
>>> 	netdev_err(bond_dev, "Error: %s\n", errmsg);		\
>>> } while (0)
>>>
>>> #define SLAVE_NL_ERR(bond_dev, slave_dev, extack, errmsg)	\
>>> do {								\
>>> 	NL_SET_ERR_MSG(extack, errmsg);				\
>>> 	slave_err(bond_dev, slave_dev, "Error: %s\n", errmsg);	\
>>> } while (0)
>>>
>>>
>>
>> I like the thought and would agree if not for how NL_SET_ERR_MSG is
>> coded. Unfortunately it does not appear as though doing the above change
>> actually generates smaller object code. Maybe I have incorrectly
>> interpreted something?
> 
> No, it's because you are compiling allyesconfig or equivalent.
> Try defconfig with bonding.
> 
> 

$ git clean -dxf
$ git log -1 -p
commit 8985f8d3fa38bca5f5384f9210ed735d58fd94f2 (HEAD -> 
upstream-bonding-cleanup)
Author: Jonathan Toppins <jtoppins@redhat.com>
Date:   Sun Aug 8 21:45:14 2021 -0400

     object code optimization

diff --git a/drivers/net/bonding/bond_main.c 
b/drivers/net/bonding/bond_main.c
index 46b95175690b..e2903ae7cdab 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1714,12 +1714,12 @@ void bond_lower_state_changed(struct slave *slave)

  #define BOND_NL_ERR(bond_dev, extack, errmsg) do {             \
         NL_SET_ERR_MSG(extack, errmsg);                         \
-       netdev_err(bond_dev, "Error: " errmsg "\n");            \
+       netdev_err(bond_dev, "Error: %s\n", errmsg);            \
  } while (0)

  #define SLAVE_NL_ERR(bond_dev, slave_dev, extack, errmsg) do { \
         NL_SET_ERR_MSG(extack, errmsg);                         \
-       slave_err(bond_dev, slave_dev, "Error: " errmsg "\n");  \
+       slave_err(bond_dev, slave_dev, "Error: %s\n", errmsg);  \
  } while (0)

  /* enslave device <slave> to bond device <master> */
$ git log --oneline -2
8985f8d3fa38 (HEAD -> upstream-bonding-cleanup) object code optimization
e326bf8fd30f bonding: combine netlink and console error messages
$ make defconfig
   HOSTCC  scripts/basic/fixdep
[...]
*** Default configuration is based on 'x86_64_defconfig'
#
# configuration written to .config
#
$ grep "BONDING" .config
# CONFIG_BONDING is not set
$ make menuconfig
   UPD     scripts/kconfig/mconf-cfg
[...]
configuration written to .config

*** End of the configuration.
*** Execute 'make' to start the build or try 'make help'.

$ grep "BONDING" .config
CONFIG_BONDING=m
$ git rebase -i --exec "make drivers/net/bonding/bond_main.o; ls -l 
drivers/net/bonding/bond_main.o" HEAD^^
Executing: make drivers/net/bonding/bond_main.o; ls -l 
drivers/net/bonding/bond_main.o
   SYNC    include/config/auto.conf.cmd
[...]
   CC      /home/jtoppins/projects/linux-rhel7/tools/objtool/librbtree.o
   LD      /home/jtoppins/projects/linux-rhel7/tools/objtool/objtool-in.o
   LINK    /home/jtoppins/projects/linux-rhel7/tools/objtool/objtool
   CC [M]  drivers/net/bonding/bond_main.o
-rw-r--r--. 1 jtoppins jtoppins 131800 Aug  8 21:47 
drivers/net/bonding/bond_main.o
Executing: make drivers/net/bonding/bond_main.o; ls -l 
drivers/net/bonding/bond_main.o
   CALL    scripts/checksyscalls.sh
   CALL    scripts/atomic/check-atomics.sh
   DESCEND objtool
   CC [M]  drivers/net/bonding/bond_main.o
-rw-r--r--. 1 jtoppins jtoppins 131928 Aug  8 21:47 
drivers/net/bonding/bond_main.o
Successfully rebased and updated refs/heads/upstream-bonding-cleanup.
$ gcc --version
gcc (GCC) 8.4.1 20200928 (Red Hat 8.4.1-1)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

-Jon