Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932600AbbFFNia (ORCPT ); Sat, 6 Jun 2015 09:38:30 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:60813 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752814AbbFFNiT (ORCPT ); Sat, 6 Jun 2015 09:38:19 -0400 From: Davidlohr Bueso To: Andrew Morton Cc: Manfred Spraul , dave@stgolabs.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Davidlohr Bueso Subject: [PATCH 1/5] ipc,shm: move BUG_ON check into shm_lock Date: Sat, 6 Jun 2015 06:37:56 -0700 Message-Id: <1433597880-8571-2-git-send-email-dave@stgolabs.net> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1433597880-8571-1-git-send-email-dave@stgolabs.net> References: <1433597880-8571-1-git-send-email-dave@stgolabs.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1838 Lines: 61 Upon every shm_lock call, we BUG_ON if an error was returned, indicating racing either in idr or in shm_destroy. Move this logic into the locking. Signed-off-by: Davidlohr Bueso --- ipc/shm.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/ipc/shm.c b/ipc/shm.c index 6d76707..6dbac3b 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -155,8 +155,14 @@ static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id) { struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); - if (IS_ERR(ipcp)) + if (IS_ERR(ipcp)) { + /* + * We raced in the idr lookup or with shm_destroy(), + * either way, the ID is busted. + */ + BUG(); return (struct shmid_kernel *)ipcp; + } return container_of(ipcp, struct shmid_kernel, shm_perm); } @@ -191,7 +197,6 @@ static void shm_open(struct vm_area_struct *vma) struct shmid_kernel *shp; shp = shm_lock(sfd->ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_atim = get_seconds(); shp->shm_lprid = task_tgid_vnr(current); shp->shm_nattch++; @@ -258,7 +263,6 @@ static void shm_close(struct vm_area_struct *vma) down_write(&shm_ids(ns).rwsem); /* remove from the list of attaches of the shm segment */ shp = shm_lock(ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_lprid = task_tgid_vnr(current); shp->shm_dtim = get_seconds(); shp->shm_nattch--; @@ -1191,7 +1195,6 @@ out_fput: out_nattch: down_write(&shm_ids(ns).rwsem); shp = shm_lock(ns, shmid); - BUG_ON(IS_ERR(shp)); shp->shm_nattch--; if (shm_may_destroy(ns, shp)) shm_destroy(ns, shp); -- 2.1.4 -- 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/