Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932993Ab2JWQkP (ORCPT ); Tue, 23 Oct 2012 12:40:15 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:48096 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755138Ab2JWQkM (ORCPT ); Tue, 23 Oct 2012 12:40:12 -0400 Date: Tue, 23 Oct 2012 11:39:48 -0500 From: Serge Hallyn To: Stanislav Kinsbursky Cc: akpm@linux-foundation.org, catalin.marinas@arm.com, will.deacon@arm.com, dhowells@redhat.com, manfred@colorfullife.com, hughd@google.com, jmorris@namei.org, mtk.manpages@gmail.com, kosaki.motohiro@jp.fujitsu.com, paulmck@linux.vnet.ibm.com, sds@tycho.nsa.gov, devel@openvz.org, a.p.zijlstra@chello.nl, cmetcalf@tilera.com, linux-driver@qlogic.com, ron.mercer@qlogic.com, viro@zeniv.linux.org.uk, eparis@parisplace.org, tglx@linutronix.de, jitendra.kalsaria@qlogic.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, ebiederm@xmission.com, casey@schaufler-ca.com Subject: Re: [PATCH v6 09/10] IPC: message queue copy feature introduced Message-ID: <20121023163948.GG9755@sergelap> References: <20121015155800.28348.23561.stgit@localhost.localdomain> <20121015160022.28348.60758.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121015160022.28348.60758.stgit@localhost.localdomain> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6576 Lines: 223 Quoting Stanislav Kinsbursky (skinsbursky@parallels.com): > This patch is required for checkpoint/restore in userspace. > IOW, c/r requires some way to get all pending IPC messages without deleting > them from the queue (checkpoint can fail and in this case tasks will be resumed, > so queue have to be valid). > To achive this, new operation flag MSG_COPY for sys_msgrcv() system call was > introduced. If this flag was specified, then mtype is interpreted as number of > the message to copy. > If MSG_COPY is set, then kernel will allocate dummy message with passed size, > and then use new copy_msg() helper function to copy desired message (instead of > unlinking it from the queue). > > Notes: > 1) Return -ENOSYS if MSG_COPY is specified, but CONFIG_CHECKPOINT_RESTORE is > not set. How much could it clean things up if a new ipc/cr.c contained #ifdef CONFIG_CHECKPOINT_RESTORE struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst) { ... } #else struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst) { return -ENOSYS; } #endif and you went on from there to try to remove all the new #ifdefs from the existing files? > Signed-off-by: Stanislav Kinsbursky > --- > include/uapi/linux/msg.h | 1 + > ipc/msg.c | 50 ++++++++++++++++++++++++++++++++++++++++++++-- > ipc/msgutil.c | 38 +++++++++++++++++++++++++++++++++++ > ipc/util.h | 1 + > 4 files changed, 88 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/msg.h b/include/uapi/linux/msg.h > index 76999c9..c1af84a 100644 > --- a/include/uapi/linux/msg.h > +++ b/include/uapi/linux/msg.h > @@ -11,6 +11,7 @@ > /* msgrcv options */ > #define MSG_NOERROR 010000 /* no error if message is too big */ > #define MSG_EXCEPT 020000 /* recv any msg except of specified type.*/ > +#define MSG_COPY 040000 /* copy (not remove) all queue messages */ > > /* Obsolete, used only for backwards compatibility and libc5 compiles */ > struct msqid_ds { > diff --git a/ipc/msg.c b/ipc/msg.c > index 9808da8..6f52c6b 100644 > --- a/ipc/msg.c > +++ b/ipc/msg.c > @@ -788,19 +788,48 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, > struct msg_msg *msg; > int mode; > struct ipc_namespace *ns; > +#ifdef CONFIG_CHECKPOINT_RESTORE > + struct msg_msg *copy = NULL; > + unsigned long copy_number = 0; > +#endif > > if (msqid < 0 || (long) bufsz < 0) > return -EINVAL; > + if (msgflg & MSG_COPY) { > +#ifdef CONFIG_CHECKPOINT_RESTORE > + > + if (msgflg & MSG_COPY) { > + copy_number = msgtyp; > + msgtyp = 0; > + } > + > + /* > + * Create dummy message to copy real message to. > + */ > + copy = load_msg(buf, bufsz); > + if (IS_ERR(copy)) > + return PTR_ERR(copy); > + copy->m_ts = bufsz; > +#else > + return -ENOSYS; > +#endif > + } > mode = convert_mode(&msgtyp, msgflg); > ns = current->nsproxy->ipc_ns; > > msq = msg_lock_check(ns, msqid); > - if (IS_ERR(msq)) > + if (IS_ERR(msq)) { > +#ifdef CONFIG_CHECKPOINT_RESTORE > + if (msgflg & MSG_COPY) > + free_msg(copy); > +#endif > return PTR_ERR(msq); > + } > > for (;;) { > struct msg_receiver msr_d; > struct list_head *tmp; > + long msg_counter = 0; > > msg = ERR_PTR(-EACCES); > if (ipcperms(ns, &msq->q_perm, S_IRUGO)) > @@ -820,8 +849,16 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, > if (mode == SEARCH_LESSEQUAL && > walk_msg->m_type != 1) { > msgtyp = walk_msg->m_type - 1; > +#ifdef CONFIG_CHECKPOINT_RESTORE > + } else if (msgflg & MSG_COPY) { > + if (copy_number == msg_counter) { > + msg = copy_msg(walk_msg, copy); > + break; > + } > +#endif > } else > break; > + msg_counter++; > } > tmp = tmp->next; > } > @@ -834,6 +871,10 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, > msg = ERR_PTR(-E2BIG); > goto out_unlock; > } > +#ifdef CONFIG_CHECKPOINT_RESTORE > + if (msgflg & MSG_COPY) > + goto out_unlock; > +#endif > list_del(&msg->m_list); > msq->q_qnum--; > msq->q_rtime = get_seconds(); > @@ -917,8 +958,13 @@ out_unlock: > break; > } > } > - if (IS_ERR(msg)) > + if (IS_ERR(msg)) { > +#ifdef CONFIG_CHECKPOINT_RESTORE > + if (msgflg & MSG_COPY) > + free_msg(copy); > +#endif > return PTR_ERR(msg); > + } > > bufsz = msg_handler(buf, msg, bufsz); > free_msg(msg); > diff --git a/ipc/msgutil.c b/ipc/msgutil.c > index 26143d3..b281f5c 100644 > --- a/ipc/msgutil.c > +++ b/ipc/msgutil.c > @@ -100,7 +100,45 @@ out_err: > free_msg(msg); > return ERR_PTR(err); > } > +#ifdef CONFIG_CHECKPOINT_RESTORE > +struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst) > +{ > + struct msg_msgseg *dst_pseg, *src_pseg; > + int len = src->m_ts; > + int alen; > + > + BUG_ON(dst == NULL); > + if (src->m_ts > dst->m_ts) > + return ERR_PTR(-EINVAL); > + > + alen = len; > + if (alen > DATALEN_MSG) > + alen = DATALEN_MSG; > + > + dst->next = NULL; > + dst->security = NULL; > > + memcpy(dst + 1, src + 1, alen); > + > + len -= alen; > + dst_pseg = dst->next; > + src_pseg = src->next; > + while (len > 0) { > + alen = len; > + if (alen > DATALEN_SEG) > + alen = DATALEN_SEG; > + memcpy(dst_pseg + 1, src_pseg + 1, alen); > + dst_pseg = dst_pseg->next; > + len -= alen; > + src_pseg = src_pseg->next; > + } > + > + dst->m_type = src->m_type; > + dst->m_ts = src->m_ts; > + > + return dst; > +} > +#endif > int store_msg(void __user *dest, struct msg_msg *msg, int len) > { > int alen; > diff --git a/ipc/util.h b/ipc/util.h > index 271bded..027f507 100644 > --- a/ipc/util.h > +++ b/ipc/util.h > @@ -142,6 +142,7 @@ int ipc_parse_version (int *cmd); > > extern void free_msg(struct msg_msg *msg); > extern struct msg_msg *load_msg(const void __user *src, int len); > +extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst); > extern int store_msg(void __user *dest, struct msg_msg *msg, int len); > > extern void recompute_msgmni(struct ipc_namespace *); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/