Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755155AbXJJJrT (ORCPT ); Wed, 10 Oct 2007 05:47:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754053AbXJJJrI (ORCPT ); Wed, 10 Oct 2007 05:47:08 -0400 Received: from ecfrec.frec.bull.fr ([129.183.4.8]:58980 "EHLO ecfrec.frec.bull.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754103AbXJJJrH (ORCPT ); Wed, 10 Oct 2007 05:47:07 -0400 Date: Wed, 10 Oct 2007 11:46:59 +0200 From: Pierre Peiffer To: Andrew Morton , Nadia Derbey Cc: linux-kernel@vger.kernel.org Subject: [PATCH] IPC: fix error case when idr-cache is empty in ipcget() Message-Id: <20071010114659.c4db806f.Pierre.Peiffer@bull.net> X-Mailer: Sylpheed 2.3.1 (GTK+ 2.10.14; i386-redhat-linux-gnu) Mime-Version: 1.0 X-MIMETrack: Itemize by SMTP Server on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 10/10/2007 11:53:25, Serialize by Router on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 10/10/2007 11:53:26, Serialize complete at 10/10/2007 11:53:26 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4537 Lines: 172 With the use of idr to store the ipc, the case where the idr cache is empty, when idr_get_new is called (this may happen even if we call idr_pre_get() before), is not well handled: it lets semget()/shmget()/msgget() return ENOSPC when this cache is empty, what 1. does not reflect the facts and 2. does not conform to the man(s). This patch fixes this by retrying the whole process of allocation in this case. Note: we could directly return ENOMEM if idr_pre_get() fails, but it does not mean that the cache is empty... This patch applies on top of 2.6.23-rc8-mm2 and should probably be merged in 2.6.24 if Nadia's patches are included. Signed-off-by: Pierre Peiffer --- ipc/msg.c | 4 ++-- ipc/sem.c | 4 ++-- ipc/shm.c | 5 +++-- ipc/util.c | 35 +++++++++++++++++++++-------------- 4 files changed, 28 insertions(+), 20 deletions(-) Index: b/ipc/msg.c =================================================================== --- a/ipc/msg.c +++ b/ipc/msg.c @@ -188,10 +188,10 @@ static int newque(struct ipc_namespace * * ipc_addid() locks msq */ id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); - if (id == -1) { + if (id < 0) { security_msg_queue_free(msq); ipc_rcu_putref(msq); - return -ENOSPC; + return id; } msq->q_perm.id = msg_buildid(ns, id, msq->q_perm.seq); Index: b/ipc/sem.c =================================================================== --- a/ipc/sem.c +++ b/ipc/sem.c @@ -269,10 +269,10 @@ static int newary(struct ipc_namespace * } id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); - if(id == -1) { + if (id < 0) { security_sem_free(sma); ipc_rcu_putref(sma); - return -ENOSPC; + return id; } ns->used_sems += nsems; Index: b/ipc/shm.c =================================================================== --- a/ipc/shm.c +++ b/ipc/shm.c @@ -409,10 +409,11 @@ static int newseg(struct ipc_namespace * if (IS_ERR(file)) goto no_file; - error = -ENOSPC; id = shm_addid(ns, shp); - if(id == -1) + if (id < 0) { + error = id; goto no_id; + } shp->shm_cprid = task_tgid_vnr(current); shp->shm_lprid = 0; Index: b/ipc/util.c =================================================================== --- a/ipc/util.c +++ b/ipc/util.c @@ -261,7 +261,7 @@ int ipc_get_maxid(struct ipc_ids *ids) * Add an entry 'new' to the IPC ids idr. The permissions object is * initialised and the first free entry is set up and the id assigned * is returned. The 'new' entry is returned in a locked state on success. - * On failure the entry is not locked and -1 is returned. + * On failure the entry is not locked and a negative err-code is returned. * * Called with ipc_ids.mutex held. */ @@ -274,11 +274,11 @@ int ipc_addid(struct ipc_ids* ids, struc size = IPCMNI; if (ids->in_use >= size) - return -1; + return -ENOSPC; err = idr_get_new(&ids->ipcs_idr, new, &id); if (err) - return -1; + return err; ids->in_use++; @@ -309,17 +309,20 @@ int ipc_addid(struct ipc_ids* ids, struc int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, struct ipc_ops *ops, struct ipc_params *params) { - int err; - - err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); - - if (!err) - return -ENOMEM; + int err, alloc; +retry: + alloc = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); mutex_lock(&ids->mutex); err = ops->getnew(ns, params); mutex_unlock(&ids->mutex); + if (err == -EAGAIN) { + if (alloc) + goto retry; + else + err = -ENOMEM; + } return err; } @@ -372,9 +375,9 @@ int ipcget_public(struct ipc_namespace * { struct kern_ipc_perm *ipcp; int flg = params->flg; - int err; - - err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); + int err, alloc; +retry: + alloc = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); mutex_lock(&ids->mutex); ipcp = ipc_findkey(ids, params->key); @@ -382,8 +385,6 @@ int ipcget_public(struct ipc_namespace * /* key not used */ if (!(flg & IPC_CREAT)) err = -ENOENT; - else if (!err) - err = -ENOMEM; else err = ops->getnew(ns, params); } else { @@ -406,6 +407,12 @@ int ipcget_public(struct ipc_namespace * } mutex_unlock(&ids->mutex); + if (err == -EAGAIN) { + if (alloc) + goto retry; + else + err = -ENOMEM; + } return err; } -- Pierre Peiffer - 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/