Re: [PATCH v2 1/2] jump_label: Explicitly disable jump labels in __init code

From: Josh Poimboeuf
Date: Sat Feb 17 2018 - 08:40:41 EST


On Sat, Feb 17, 2018 at 11:38:48AM +0100, Ingo Molnar wrote:
>
> * Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
>
> > +/* Disable any jump label entries in __init code */
> > +void __init jump_label_invalidate_init(void)
> > +{
> > + struct jump_entry *iter_start = __start___jump_table;
> > + struct jump_entry *iter_stop = __stop___jump_table;
> > + struct jump_entry *iter;
> > +
> > + for (iter = iter_start; iter < iter_stop; iter++)
> > + if (iter->code >= (unsigned long)_sinittext &&
> > + iter->code < (unsigned long)_einittext)
> > + iter->code = 0;
> > +}
> > +
> > +/* Disable any jump label entries in module init code */
> > static void jump_label_invalidate_module_init(struct module *mod)
> > {
> > struct jump_entry *iter_start = mod->jump_entries;
> > struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
> > struct jump_entry *iter;
> >
> > - for (iter = iter_start; iter < iter_stop; iter++) {
> > + for (iter = iter_start; iter < iter_stop; iter++)
> > if (within_module_init(iter->code, mod))
> > iter->code = 0;
> > - }
>
> Why did you remove the curly braces? They are canonical kernel style for
> multi-line statements.
>
> The new jump_label_invalidate_init() function has that problem too.

I'd say the jury is still out:

Without braces:

$ find . -name "*.[ch]" | xargs awk '/for \(.*[^{]$/ { line1=$0; f=1; next } f == 1 && /if \(.*[^{]$/ { f=0; line2=$0; i=1; next } i == 1 { i=0; line3=$0; j=1; next } j == 1 && /^$/ {j=0; print line1; print line2; print line3; print; next} { f=0; i=0; j=0; }' |grep 'for (' |wc -l
1389

With braces:

$ find . -name "*.[ch]" | xargs awk '/for \(.*{$/ { line1=$0; f=1; next } f == 1 && /if \(.*[^{]$/ { f=0; line2=$0; i=1; next } i == 1 { i=0; line3=$0; j=1; next } j == 1 && /}/ {j=0; print line1; print line2; print line3; print } { f=0; i=0; j=0; }' |grep 'for (' |wc -l
2292

And I see no mention of it in coding-style.rst.

Personally I prefer the more compact version, but I have no problem
changing it.

--
Josh