From 0cfea4bc8f6e5a54d2c001089607dd7bf3ceec19 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Fri, 2 Feb 2024 00:39:42 +0000 Subject: [PATCH] xen: Swap order of actions in the FREE*() macros Wherever possible, it is a good idea to NULL out the visible reference to an object prior to freeing it. The FREE*() macros already collect together both parts, making it easy to adjust. This has a marginal code generation improvement, as some of the calls to the free() function can be tailcall optimised. No functional change. Signed-off-by: Andrew Cooper Acked-by: Jan Beulich (cherry picked from commit c4f427ec879e7c0df6d44d02561e8bee838a293e) --- xen/include/xen/mm.h | 3 ++- xen/include/xen/xmalloc.h | 7 ++++--- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h index 3f5c296138..c0b77d563d 100644 --- a/xen/include/xen/mm.h +++ b/xen/include/xen/mm.h @@ -80,8 +80,9 @@ bool scrub_free_pages(void); /* Free an allocation, and zero the pointer to it. */ #define FREE_XENHEAP_PAGES(p, o) do { \ - free_xenheap_pages(p, o); \ + void *_ptr_ = (p); \ (p) = NULL; \ + free_xenheap_pages(_ptr_, o); \ } while ( false ) #define FREE_XENHEAP_PAGE(p) FREE_XENHEAP_PAGES(p, 0) diff --git a/xen/include/xen/xmalloc.h b/xen/include/xen/xmalloc.h index 16979a117c..d857298011 100644 --- a/xen/include/xen/xmalloc.h +++ b/xen/include/xen/xmalloc.h @@ -66,9 +66,10 @@ extern void xfree(void *); /* Free an allocation, and zero the pointer to it. */ -#define XFREE(p) do { \ - xfree(p); \ - (p) = NULL; \ +#define XFREE(p) do { \ + void *_ptr_ = (p); \ + (p) = NULL; \ + xfree(_ptr_); \ } while ( false ) /* Underlying functions */ -- 2.39.5