Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755938Ab0HXUnN (ORCPT ); Tue, 24 Aug 2010 16:43:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15306 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753091Ab0HXUnK (ORCPT ); Tue, 24 Aug 2010 16:43:10 -0400 From: Eric Paris To: linux-kernel@vger.kernel.org Cc: Eric Paris , Andreas Schwab , Tvrtko Ursulin , Andreas Gruenbacher Subject: [PATCH -v2] fanotify: drops the packed attribute from userspace event metadata Date: Tue, 24 Aug 2010 16:43:02 -0400 Message-Id: <1282682582-15980-1-git-send-email-eparis@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1813 Lines: 57 The userspace event metadata structure was packed so when sent from a kernel with a certain set of alignment rules to a userspace listener with a different set of alignment rules the userspace process would be able to use the structure. On some arches just using packed, even if it doesn't do anything to the alignment can cause a severe performance hit. From now on we are not going to set the packed attribute and will just need to be very careful to make sure the structure is naturally aligned. Cc: Andreas Schwab Cc: Tvrtko Ursulin Cc: Andreas Gruenbacher Signed-off-by: Eric Paris --- include/linux/fanotify.h | 13 ++++++++----- 1 files changed, 8 insertions(+), 5 deletions(-) diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index 0535461..b892e46 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -65,20 +65,23 @@ FAN_ALL_PERM_EVENTS |\ FAN_Q_OVERFLOW) -#define FANOTIFY_METADATA_VERSION 1 - +#define FANOTIFY_METADATA_VERSION 2 +/* + * These structures must be naturally aligned so that a 32 bit userspace process + * will find the offsets the same as a 64bit process. + */ struct fanotify_event_metadata { __u32 event_len; __u32 vers; - __u64 mask; + aligned_u64 mask; __s32 fd; __s32 pid; -} __attribute__ ((packed)); +}; struct fanotify_response { __s32 fd; __u32 response; -} __attribute__ ((packed)); +}; /* Legit userspace responses to a _PERM event */ #define FAN_ALLOW 0x01 -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/