Inline Macro issue

[Saket Sinha]

Russel:
Thank you a curly bracket was missing. How could I not notice.
Valdis:
I shall take your suggestions.
Mandeep:
Thank you for that enlighting ideas

Regards,
Saket Sinha



On Mon, Jul 15, 2013 at 7:52 PM, <Valdis.Kletnieks at vt.edu> wrote:

> On Mon, 15 Jul 2013 17:39:15 +0530, Mandeep Sandhu said:
>
> > #define push_root() \
> >       recursive_mutex_lock(&context->id_lock);        \
> >       context->uid = current->fsuid;                  \
> >       context->gid = current->fsgid;                  \
> >         do {                                            \
> >             struct cred *new1 = prepare_creds();           \
> >             //make changes to any member of this structure \
> >             commit_creds(new1);                            \
> >         } while(0);
>
> Actually, this has 3 problems:
>
> 1) You have a call to mutex_loc() that doesn't get unlocked. This Is Bad.
>
> 2) If you're using the 'do { foo } while (0)' trick, you want to
> put the *whole thing* inside the { } (Hint - you can put local variable
> definitions inside the curlies as well).
>
> 3) Leave the ; off the 'while (0)' in the macro definition, because:
>
> > int main()
> > {
> >    printf("in main\n");
> >    pushme
> >   return 0;
> > }
>
> Somebody will forget and put a ; after pushme - and in some contexts, the
> additional ; will then cause issues.
>
>
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