Re: [PATCH 1/2] Move kfree_call_rcu() to slab_common.c

[Rao Shoaib]

On 01/04/2018 01:46 PM, Matthew Wilcox wrote:
> On Thu, Jan 04, 2018 at 01:27:49PM -0800, Rao Shoaib wrote:
> > On 01/04/2018 12:35 PM, Rao Shoaib wrote:
> > > As far as your previous comments are concerned, only the following one
> > > has not been addressed. Can you please elaborate as I do not understand
> > > the comment. The code was expanded because the new macro expansion check
> > > fails. Based on Matthew Wilcox's comment I have reverted rcu_head_name
> > > back to rcu_head.
> > It turns out I did not remember the real reason for the change. With the
> > macro rewritten, using rcu_head as a macro argument does not work because it
> > conflicts with the name of the type 'struct rcu_head' used in the macro. I
> > have renamed the macro argument to rcu_name.
> >
> > Shoaib
> > > > +#define kfree_rcu(ptr, rcu_head_name) \
> > > > +ÂÂÂ do { \
> > > > +ÂÂÂÂÂÂÂ typeof(ptr) __ptr = ptr;ÂÂÂ \
> > > > +ÂÂÂÂÂÂÂ unsigned long __off = offsetof(typeof(*(__ptr)), \
> > > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ rcu_head_name); \
> > > > +ÂÂÂÂÂÂÂ struct rcu_head *__rptr = (void *)__ptr + __off; \
> > > > +ÂÂÂÂÂÂÂ __kfree_rcu(__rptr, __off); \
> > > > +ÂÂÂ } while (0)
> > > why do you want to open code this?
> But why are you changing this macro at all?  If it was to avoid the
> double-mention of "ptr", then you haven't done that.
I have -- I do not get the error because ptr is being assigned only one. 
If you have a better way than let me know and I will be happy to make 
the change.

Shoaib.