From 40df03fc6ff8410b3d9aa2e7bb5163b698c39b3e Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 15 Dec 2017 11:15:54 +0100 Subject: [PATCH] x86: use switch() in _put_page_type() Use this to cheaply add another assertion. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/mm.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 53a211e3bb..b8eb4feb6b 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -2458,8 +2458,9 @@ static int _put_page_type(struct page_info *page, bool preemptible, ASSERT((x & PGT_count_mask) != 0); - if ( unlikely((nx & PGT_count_mask) == 0) ) + switch ( nx & (PGT_locked | PGT_count_mask) ) { + case 0: if ( unlikely((nx & PGT_type_mask) <= PGT_l4_page_table) && likely(nx & (PGT_validated|PGT_partial)) ) { @@ -2495,10 +2496,14 @@ static int _put_page_type(struct page_info *page, bool preemptible, } else BUG_ON(!IS_ENABLED(CONFIG_PV_LINEAR_PT)); - } - else if ( unlikely((nx & (PGT_locked | PGT_count_mask)) == - (PGT_locked | 1)) ) - { + + break; + + case PGT_locked: + ASSERT_UNREACHABLE(); + return -EILSEQ; + + case PGT_locked | 1: /* * We must not drop the second to last reference when the page is * locked, as page_unlock() doesn't do any cleanup of the type. -- 2.39.5