On Thu, May 21, 2020 at 02:31:17PM +0200, Petr Mladek wrote:
> On Wed 2020-05-20 21:40:07, Andrew Morton wrote:
> > On Thu, 21 May 2020 13:36:28 +0900 Sergey Senozhatsky
> > <sergey.senozhat...@gmail.com> wrote:
> >
> > > On (20/05/20 18:00), Andrew Morton wrote:
> > > [..]
> > > > I'm wondering if we shold add a kernel puts() (putsk()? yuk) which can
> > > > puts() a string of any length.
> > > >
> > > > I'm counting around 150 instances of printk("%s", ...) and pr_foo("%s",
> > > > ...) which could perhaps be converted, thus saving an argument.
> > >
> > > Can you point me at some examples?
> > >
> >
> > ./arch/powerpc/kernel/udbg.c: printk("%s", s);
> > ./arch/powerpc/xmon/nonstdio.c: printk("%s", xmon_outbuf);
> > ./arch/um/os-Linux/drivers/ethertap_user.c: printk("%s",
> > output);
> > ./arch/um/os-Linux/drivers/ethertap_user.c: printk("%s",
> > output);
> > ./arch/um/os-Linux/drivers/tuntap_user.c:
> > printk("%s", out
> >
> > etc.
> >
> > My point is, if we created a length-unlimited puts() function for printing
> > the
> > kernel command line, it could be reused in such places, resulting in a
> > smaller kernel.
>
> Interesting idea. Well, such a generic function would need to be safe
> and do not modify the original string. We would need to implement
> printk() variant that would support strigs limited by size instead
> of the trailing '\0'. I am not sure if it is worth it.
>
> Best Regards,
> Petr
You don't need a printk variant for strings -- you'd only need one if
you wanted formatted output of unlimited length. Using printk("%.*s",
chunk_size, str) should print at most chunk_size characters from str.
The puts could then just be a loop around that.
Something like:
do {
printed = printk("%.*s", chunk_size, str);
str += printed;
} while (printed >= chunk_size);
