From: Stanislav Kinsbursky <skinsbursky@parallels.com>
To: akpm@linux-foundation.org
Cc: serge.hallyn@canonical.com, ebiederm@xmission.com,
linux-kernel@vger.kernel.org, xemul@parallels.com,
catalin.marinas@arm.com, will.deacon@arm.com, jmorris@namei.org,
cmetcalf@tilera.com, joe.korty@ccur.com, dhowells@redhat.com,
dledford@redhat.com, viro@zeniv.linux.org.uk,
kosaki.motohiro@jp.fujitsu.com, linux-api@vger.kernel.org,
serue@us.ibm.com, tglx@linutronix.de, paulmck@linux.vnet.ibm.com,
devel@openvz.org, mtk.manpages@gmail.com
Subject: [PATCH v8 4/5] ipc: message queue copy feature introduced
Date: Wed, 24 Oct 2012 19:35:20 +0400 [thread overview]
Message-ID: <20121024153520.5642.4297.stgit@localhost.localdomain> (raw)
In-Reply-To: <20121024151555.5642.79086.stgit@localhost.localdomain>
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.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
---
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 78dbd2f..22d95c6 100644
--- a/include/uapi/linux/msg.h
+++ b/include/uapi/linux/msg.h
@@ -10,6 +10,7 @@
/* 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 532ebc3..28320ab 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -777,19 +777,48 @@ 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))
@@ -809,8 +838,16 @@ 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;
}
@@ -823,6 +860,10 @@ 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();
@@ -906,8 +947,13 @@ 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 a61e0ca..eeb79a1 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -140,6 +140,7 @@ 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 *);
next prev parent reply other threads:[~2012-10-24 15:37 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-24 15:34 [RFC PATCH v8 0/5] IPC: checkpoint/restore in userspace enhancements Stanislav Kinsbursky
2012-10-24 15:35 ` [PATCH v8 1/5] ipc: remove forced assignment of selected message Stanislav Kinsbursky
2012-10-24 15:35 ` [PATCH v8 2/5] ipc: add sysctl to specify desired next object id Stanislav Kinsbursky
2012-10-24 21:41 ` Andrew Morton
2012-10-25 7:53 ` Stanislav Kinsbursky
2012-10-24 15:35 ` [PATCH v8 3/5] ipc: message queue receive cleanup Stanislav Kinsbursky
2012-10-24 15:35 ` Stanislav Kinsbursky [this message]
2012-10-24 21:41 ` [PATCH v8 4/5] ipc: message queue copy feature introduced Andrew Morton
2012-10-24 15:35 ` [PATCH v8 5/5] test: IPC message queue copy feture test Stanislav Kinsbursky
2012-10-24 21:42 ` [RFC PATCH v8 0/5] IPC: checkpoint/restore in userspace enhancements Andrew Morton
2012-12-18 20:36 ` Andrew Morton
2012-12-20 4:06 ` Stanislav Kinsbursky
2012-12-20 20:47 ` Andrew Morton
2012-12-21 20:46 ` Stanislav Kinsbursky
2012-12-21 21:57 ` Sasha Levin
2012-12-22 15:43 ` Sasha Levin
2013-01-09 8:24 ` Stanislav Kinsbursky
2013-01-14 6:31 ` Sasha Levin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121024153520.5642.4297.stgit@localhost.localdomain \
--to=skinsbursky@parallels.com \
--cc=akpm@linux-foundation.org \
--cc=catalin.marinas@arm.com \
--cc=cmetcalf@tilera.com \
--cc=devel@openvz.org \
--cc=dhowells@redhat.com \
--cc=dledford@redhat.com \
--cc=ebiederm@xmission.com \
--cc=jmorris@namei.org \
--cc=joe.korty@ccur.com \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mtk.manpages@gmail.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=serge.hallyn@canonical.com \
--cc=serue@us.ibm.com \
--cc=tglx@linutronix.de \
--cc=viro@zeniv.linux.org.uk \
--cc=will.deacon@arm.com \
--cc=xemul@parallels.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).