On Wed, Oct 18, 2006 at 08:04:24AM -0700, Linus Torvalds wrote:
> On Wed, 18 Oct 2006, Al Viro wrote:
> >
> > +#define lock_super(x) do { \
> > + struct super_block *sb = x; \
> > + get_fs_excl(); \
> > + mutex_lock(&sb->s_lock); \
> > +} while(0)
>
> Don't do this. The "x" passed in may be "sb", and then you end up with
> bogus code.
For this one, I see a third way:
#define lock_super(sb) do { \
get_fs_excl(); \
mutex_lock(&(sb)->s_lock); \
} while (0)
It does have the disadvantage that you can pass *anything* that has
an s_lock field in ... but I don't think that's a very likely thing
to happen.
Or you could use _sb as the local variable, since it's a reserved
identifier.
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