From 8dab5241d06bfc9ee141ea78c56cde5070d7460d Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Sat, 16 Jun 2007 10:16:12 -0700 Subject: Rework ptep_set_access_flags and fix sun4c Some changes done a while ago to avoid pounding on ptep_set_access_flags and update_mmu_cache in some race situations break sun4c which requires update_mmu_cache() to always be called on minor faults. This patch reworks ptep_set_access_flags() semantics, implementations and callers so that it's now responsible for returning whether an update is necessary or not (basically whether the PTE actually changed). This allow fixing the sparc implementation to always return 1 on sun4c. [akpm@linux-foundation.org: fixes, cleanups] Signed-off-by: Benjamin Herrenschmidt Cc: Hugh Dickins Cc: David Miller Cc: Mark Fortescue Acked-by: William Lee Irwin III Cc: "Luck, Tony" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-generic/pgtable.h | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index dc8f99ee305..7d7bcf990e9 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -27,13 +27,20 @@ do { \ * Largely same as above, but only sets the access flags (dirty, * accessed, and writable). Furthermore, we know it always gets set * to a "more permissive" setting, which allows most architectures - * to optimize this. + * to optimize this. We return whether the PTE actually changed, which + * in turn instructs the caller to do things like update__mmu_cache. + * This used to be done in the caller, but sparc needs minor faults to + * force that call on sun4c so we changed this macro slightly */ #define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \ -do { \ - set_pte_at((__vma)->vm_mm, (__address), __ptep, __entry); \ - flush_tlb_page(__vma, __address); \ -} while (0) +({ \ + int __changed = !pte_same(*(__ptep), __entry); \ + if (__changed) { \ + set_pte_at((__vma)->vm_mm, (__address), __ptep, __entry); \ + flush_tlb_page(__vma, __address); \ + } \ + __changed; \ +}) #endif #ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG -- cgit v1.2.3