From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: + mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem.patch added to -mm tree Date: Mon, 24 Nov 2008 15:22:19 -0800 Message-ID: <200811242322.mAONMKBG021992@imap1.linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:42033 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753432AbYKXXWw (ORCPT ); Mon, 24 Nov 2008 18:22:52 -0500 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: mm-commits@vger.kernel.org Cc: julia@diku.dk The patch titled mm/page_alloc.c: eliminate NULL test and memset after alloc_bootmem has been added to the -mm tree. Its filename is mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mm/page_alloc.c: eliminate NULL test and memset after alloc_bootmem From: Julia Lawall As noted by Akinobu Mita in patch b1fceac2b9e04d278316b2faddf276015fc06e3b, alloc_bootmem and related functions never return NULL and always return a zeroed region of memory. Thus a NULL test or memset after calls to these functions is unnecessary. This was fixed using the following semantic patch. (http://www.emn.fr/x-info/coccinelle/) // @@ expression E; statement S; @@ E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\|alloc_bootmem_node\|alloc_bootmem_low_pages_node\|alloc_bootmem_pages_node\)(...) ... when != E ( - BUG_ON (E == NULL); | - if (E == NULL) S ) @@ expression E,E1; @@ E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\|alloc_bootmem_node\|alloc_bootmem_low_pages_node\|alloc_bootmem_pages_node\)(...) ... when != E - memset(E,0,E1); // Signed-off-by: Julia Lawall Signed-off-by: Andrew Morton --- mm/page_alloc.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff -puN mm/page_alloc.c~mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem mm/page_alloc.c --- a/mm/page_alloc.c~mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem +++ a/mm/page_alloc.c @@ -3396,10 +3396,8 @@ static void __init setup_usemap(struct p { unsigned long usemapsize = usemap_size(zonesize); zone->pageblock_flags = NULL; - if (usemapsize) { + if (usemapsize) zone->pageblock_flags = alloc_bootmem_node(pgdat, usemapsize); - memset(zone->pageblock_flags, 0, usemapsize); - } } #else static void inline setup_usemap(struct pglist_data *pgdat, _ Patches currently in -mm which might be from julia@diku.dk are linux-next.patch drivers-char-agp-add-missing-pci_dev_get.patch drivers-mtd-maps-nettelc-use-array_size.patch net-tipc-bcasth-use-array_size.patch drivers-isdn-misdn-use-array_size.patch drivers-pci-hotplug-add-missing-pci_dev_get.patch drivers-message-fusion-use-array_size.patch fs-namespacec-drop-code-after-return.patch arch-arm-eliminate-null-test-and-memset-after-alloc_bootmem.patch arch-avr32-eliminate-null-test-and-memset-after-alloc_bootmem.patch arch-ia64-eliminate-null-test-and-memset-after-alloc_bootmem.patch arch-powerpc-eliminate-null-test-and-memset-after-alloc_bootmem.patch mm-page_allocc-eliminate-null-test-and-memset-after-alloc_bootmem.patch