Re: [PATCH net-next 2/2] bonding: combine netlink and console error messages

[Jonathan Toppins]

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?

$ git show
commit 6bb346263b4e9d008744b45af5105df309c35c1a (HEAD -> 
upstream-bonding-cleanup)
Author: Jonathan Toppins <jtoppins@xxxxxxxxxx>
Date:   Sat Aug 7 17:34:58 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 -3
6bb346263b4e (HEAD -> upstream-bonding-cleanup) object code optimization
a36c7639a139 bonding: combine netlink and console error messages
88916c847e85 bonding: remove extraneous definitions from bonding.h
jtoppins@jtoppins:~/projects/linux-rhel7$ git rebase -i --exec "make 
drivers/net/bonding/bond_main.o; ls -l drivers/net/bonding/bond_main.o" 
HEAD^^
hint: Waiting for your editor to close the file... Error detected while 
processing 
/home/jtoppins/.vim/bundle/cscope_macros.vim/plugin/cscope_macros.vim:
line   42:
E568: duplicate cscope database not added
Press ENTER or type command to continue
Executing: make menuconfig


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

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
  DESCEND bpf/resolve_btfids
  CC [M]  drivers/net/bonding/bond_main.o
-rw-r--r--. 1 jtoppins jtoppins 1777896 Aug  7 17:37 
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
  DESCEND bpf/resolve_btfids
  CC [M]  drivers/net/bonding/bond_main.o
-rw-r--r--. 1 jtoppins jtoppins 1778320 Aug  7 17:37 
drivers/net/bonding/bond_main.o
Successfully rebased and updated refs/heads/upstream-bonding-cleanup.

It appears the change increases bond_main.o by 424 (1778320-1777896) bytes.