From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Haggerty Subject: [PATCH v3 18/25] struct lock_file: declare some fields volatile Date: Mon, 14 Apr 2014 15:54:48 +0200 Message-ID: <1397483695-10888-19-git-send-email-mhagger@alum.mit.edu> References: <1397483695-10888-1-git-send-email-mhagger@alum.mit.edu> Cc: git@vger.kernel.org, Johannes Sixt , Jeff King , =?UTF-8?q?Torsten=20B=C3=B6gershausen?= , Eric Sunshine , Michael Haggerty To: Junio C Hamano X-From: git-owner@vger.kernel.org Mon Apr 14 15:55:54 2014 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WZhMU-0000ez-2h for gcvg-git-2@plane.gmane.org; Mon, 14 Apr 2014 15:55:50 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755244AbaDNNzn (ORCPT ); Mon, 14 Apr 2014 09:55:43 -0400 Received: from alum-mailsec-scanner-4.mit.edu ([18.7.68.15]:55519 "EHLO alum-mailsec-scanner-4.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755213AbaDNNzi (ORCPT ); Mon, 14 Apr 2014 09:55:38 -0400 X-AuditID: 1207440f-f79326d000003c9f-61-534be8d9656b Received: from outgoing-alum.mit.edu (OUTGOING-ALUM.MIT.EDU [18.7.68.33]) by alum-mailsec-scanner-4.mit.edu (Symantec Messaging Gateway) with SMTP id 0F.65.15519.9D8EB435; Mon, 14 Apr 2014 09:55:37 -0400 (EDT) Received: from michael.fritz.box (p4FC96FF6.dip0.t-ipconnect.de [79.201.111.246]) (authenticated bits=0) (User authenticated as mhagger@ALUM.MIT.EDU) by outgoing-alum.mit.edu (8.13.8/8.12.4) with ESMTP id s3EDt09I010903 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Mon, 14 Apr 2014 09:55:35 -0400 X-Mailer: git-send-email 1.9.1 In-Reply-To: <1397483695-10888-1-git-send-email-mhagger@alum.mit.edu> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrOIsWRmVeSWpSXmKPExsUixO6iqHvzhXewwbdtChZdV7qZLBp6rzBb rPxZY3F7xXxmi1+Hn7Bb/GjpYbY486aR0aKz4yujA4fH3/cfmDx2zrrL7vGsdw+jx8VLyh6L H3h5fN4k53H3/04mj9vPtrEEcERx2yQllpQFZ6bn6dslcGe82nCZtWCrUEX/vmfsDYyt/F2M nBwSAiYS//ccYIKwxSQu3FvP1sXIxSEkcJlRYnfDUkaQhJDASSaJx1crQWw2AV2JRT3NYA0i AmoSE9sOsYA0MAu0M0kc2tELlhAW8JCY03qJGcRmEVCVaH61HWgqBwevgKvEmR3SEMvkJE4e m8wKEuYECi/8kAWxykXi7pcprBMYeRcwMqxilEvMKc3VzU3MzClOTdYtTk7My0st0jXRy80s 0UtNKd3ECAlE/h2MXetlDjEKcDAq8fB2zPEOFmJNLCuuzD3EKMnBpCTKm3EDKMSXlJ9SmZFY nBFfVJqTWnyIUYKDWUmE13UrUI43JbGyKrUoHyYlzcGiJM6rvkTdT0ggPbEkNTs1tSC1CCYr w8GhJMFrDIw4IcGi1PTUirTMnBKENBMHJ8hwLimR4tS8lNSixNKSjHhQXMQXAyMDJMUDtDfp Ocje4oLEXKAoROspRkUpcd4SkIQASCKjNA9uLCy9vGIUB/pSmFcCZDsPMDXBdb8CGswENJil HWxwSSJCSqqBka9b0PGCrOnuwBPxnsrMb9om/2NpyNQ50xs0Lyj5/e/HKcK6TycseBq3u4B1 g5NW9bETPif4p1XxXbiqvXTiUZmuU+Ibf/DvbPikwSTO2yNvrniXseiPfEbMIYUp Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: The function remove_lock_file_on_signal() is used as a signal handler. It is not realistic to make the signal handler conform strictly to the C standard, which is very restrictive about what a signal handler is allowed to do. But let's increase the likelihood that it will work: The lock_file_list global variable and several fields from struct lock_file are used by the signal handler. Declare those values "volatile" to increase the chance that the signal handler will see a valid object state. Suggested-by: Johannes Sixt Signed-off-by: Michael Haggerty --- cache.h | 6 +++--- lockfile.c | 2 +- refs.c | 5 +++-- 3 files changed, 7 insertions(+), 6 deletions(-) diff --git a/cache.h b/cache.h index b7af173..9019c7d 100644 --- a/cache.h +++ b/cache.h @@ -538,10 +538,10 @@ extern int refresh_index(struct index_state *, unsigned int flags, const struct #define LOCK_SUFFIX_LEN 5 struct lock_file { - struct lock_file *next; + struct lock_file *volatile next; volatile sig_atomic_t active; - int fd; - pid_t owner; + volatile int fd; + volatile pid_t owner; char on_list; char filename[PATH_MAX]; }; diff --git a/lockfile.c b/lockfile.c index 50a0541..fce53f1 100644 --- a/lockfile.c +++ b/lockfile.c @@ -69,7 +69,7 @@ * See Documentation/api-lockfile.txt for more information. */ -static struct lock_file *lock_file_list; +static struct lock_file *volatile lock_file_list; static const char *alternate_index_output; static void remove_lock_file(void) diff --git a/refs.c b/refs.c index cb2f825..db8057c 100644 --- a/refs.c +++ b/refs.c @@ -2213,15 +2213,16 @@ int commit_packed_refs(void) struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(&ref_cache); int error = 0; + int fd; if (!packed_ref_cache->lock) die("internal error: packed-refs not locked"); write_or_die(packed_ref_cache->lock->fd, PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER)); + fd = packed_ref_cache->lock->fd; do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache), - 0, write_packed_entry_fn, - &packed_ref_cache->lock->fd); + 0, write_packed_entry_fn, &fd); if (commit_lock_file(packed_ref_cache->lock)) error = -1; packed_ref_cache->lock = NULL; -- 1.9.1