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

From: Rao Shoaib
Date: Thu Jan 04 2018 - 17:19:17 EST




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.