From 782a6b951a2317e1c3ecc81b6d94be09157fc363 Mon Sep 17 00:00:00 2001 From: Paul Durrant Date: Thu, 4 Jul 2019 16:03:47 +0200 Subject: [PATCH] xmalloc: stop using a magic '1' in alignment padding Alignment padding inserts a pseudo block header in front of the allocation, sets its size field to the pad size and then ORs in 1, which is equivalent to marking it as a free block, so that xfree() can distinguish it from a real block header. This patch simply replaces the magic '1' with the defined 'FREE_BLOCK' to make it more obvious what's going on. Also, whilst in the neighbourhood, it removes a stray space after a cast. Signed-off-by: Paul Durrant Reviewed-by: Jan Beulich --- xen/common/xmalloc_tlsf.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/xen/common/xmalloc_tlsf.c b/xen/common/xmalloc_tlsf.c index 2076953ac4..f585388dfa 100644 --- a/xen/common/xmalloc_tlsf.c +++ b/xen/common/xmalloc_tlsf.c @@ -595,7 +595,7 @@ void *_xmalloc(unsigned long size, unsigned long align) char *q = (char *)p + pad; struct bhdr *b = (struct bhdr *)(q - BHDR_OVERHEAD); ASSERT(q > (char *)p); - b->size = pad | 1; + b->size = pad | FREE_BLOCK; p = q; } @@ -638,12 +638,12 @@ void xfree(void *p) } /* Strip alignment padding. */ - b = (struct bhdr *)((char *) p - BHDR_OVERHEAD); - if ( b->size & 1 ) + b = (struct bhdr *)((char *)p - BHDR_OVERHEAD); + if ( b->size & FREE_BLOCK ) { - p = (char *)p - (b->size & ~1u); + p = (char *)p - (b->size & ~FREE_BLOCK); b = (struct bhdr *)((char *)p - BHDR_OVERHEAD); - ASSERT(!(b->size & 1)); + ASSERT(!(b->size & FREE_BLOCK)); } xmem_pool_free(p, xenpool); -- 2.30.2