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 <[email protected]> --- CC: George Dunlap <[email protected]> CC: Jan Beulich <[email protected]> CC: Stefano Stabellini <[email protected]> CC: Wei Liu <[email protected]> CC: Julien Grall <[email protected]> --- 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 3d9b2d05a5c8..044f3f3b19c8 100644 --- a/xen/include/xen/mm.h +++ b/xen/include/xen/mm.h @@ -92,8 +92,9 @@ 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 9ecddbff5e00..1b88a83be879 100644 --- a/xen/include/xen/xmalloc.h +++ b/xen/include/xen/xmalloc.h @@ -66,9 +66,10 @@ extern void xfree(void *p); /* 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 */ base-commit: 3f819af8a796c0e2f798dd301ec8c3f8cccbc9fc -- 2.30.2
