Re: [PATCH 1/4] Net device error logging, revised

[Jeff Garzik <jgarzik@xxxxxxxxx>]

Jim Keniston wrote:
> #define netdev_printk(sevlevel, netdev, msglevel, format, arg...)       \
> do {                                                                    \
> if (NETIF_MSG_##msglevel == NETIF_MSG_ALL || ((netdev)->msg_enable & 
> NETIF_MSG_##msglevel)) {    \
>         char pfx[40];                                                   \
>         printk(sevlevel "%s: " format , make_netdev_msg_prefix(pfx, netdev) , 
> ## arg);        \
> }} while (0)
>
> This would make your code bigger, but not that much bigger for the common case 
> where
> the msglevel is omitted (and the 'if(...)' is optimized out).


"NETIF_MSG_" is silly and should be eliminated.
A separate "NETIF_MSG_ALL" test is not needed, because msg_enable is a 
bitmask.  A msg_enable of 0xffffffff will naturally create a NETIF_MSG_ALL.

Also, whatever mechanism is created, it needs to preserve the feature of 
the existing system:

        if (a quick bitmask test)
                do something

And preferably "do something" is not inlined, because printk'ing -- 
although it may appear in a fast path during debugging -- cannot be 
considered a fast path itself.

        Jeff