hello,
this patch is part of my pNFS/GFS2 work and i'd neglected at
first to send it to the correct mailing list. i'm a little unsure of how
to broach it, however, since the subsequent patches that then actually
make use of this aren't germane to the list.
i'd appreciate any and all criticism -- i've already gotten a
couple good suggestions from someone at EMC who's been trying it out.
thanks for your time,
d
.
The rpc_pipefs upcall/downcall mechanism is a particularly useful means by
which to communicate between the kernel and userspace, and its pipe-oriented
nature makes it familiar to Unix programmers.
simple_rpc_pipefs is a small API that simplifies tasks that commonly arise with
rpc_pipefs, like making an upcall and blocking the calling thread until a reply
is received, among other things.
Note: the one portion of the existing rpc_pipe_fs code that has been changed is
that struct rpc_pipe_msg has had a u8 "flags" variable added. The purpose is to
allow callers to indicate when making an upcall that a dynamically allocated
upcall message buffer and/or struct rpc_pipe_msg should be automatically freed
in the ->destroy_msg() callback; pipefs_generic_destroy_msg() implements this
using the new PIPEFS_AUTOFREE_UPCALL_MSG and PIPEFS_AUTOFREE_RPCMSG flags,
respectively.
The arguments for not setting those flags in pipefs_hdr_t's "flags" variable is
that 1) they would be exposed to userland and 2) are orthogonal to a message's
content.
---
include/linux/sunrpc/rpc_pipe_fs.h | 4 +
include/linux/sunrpc/simple_rpc_pipefs.h | 99 +++++++
net/sunrpc/Makefile | 2 +-
net/sunrpc/simple_rpc_pipefs.c | 424 ++++++++++++++++++++++++++++++
4 files changed, 528 insertions(+), 1 deletions(-)
create mode 100644 include/linux/sunrpc/simple_rpc_pipefs.h
create mode 100644 net/sunrpc/simple_rpc_pipefs.c
diff --git a/include/linux/sunrpc/rpc_pipe_fs.h b/include/linux/sunrpc/rpc_pipe_fs.h
index 51b977a..3850d69 100644
--- a/include/linux/sunrpc/rpc_pipe_fs.h
+++ b/include/linux/sunrpc/rpc_pipe_fs.h
@@ -9,6 +9,10 @@ struct rpc_pipe_msg {
size_t len;
size_t copied;
int errno;
+#define PIPEFS_AUTOFREE_RPCMSG 0x01 /* ->destroy_msg frees rpc_pipe_msg */
+#define PIPEFS_AUTOFREE_RPCMSG_DATA 0x02 /* ->destroy_msg frees rpc_pipe_msg->data */
+#define PIPEFS_AUTOFREE_UPCALL_MSG PIPEFS_AUTOFREE_RPCMSG_DATA
+ u8 flags;
};
struct rpc_pipe_ops {
diff --git a/include/linux/sunrpc/simple_rpc_pipefs.h b/include/linux/sunrpc/simple_rpc_pipefs.h
new file mode 100644
index 0000000..bab94bc
--- /dev/null
+++ b/include/linux/sunrpc/simple_rpc_pipefs.h
@@ -0,0 +1,99 @@
+/*
+ * linux/fs/gfs2/simple_rpc_pipefs.h
+ *
+ * Copyright (c) 2008 The Regents of the University of Michigan.
+ * All rights reserved.
+ *
+ * David M. Richter <richterd@xxxxxxxxxxxxxx>
+ *
+ * Drawing on work done by Andy Adamson <andros@xxxxxxxxxxxxxx> and
+ * Marius Eriksen <marius@xxxxxxxxxx>. Thanks for the help over the
+ * years, guys.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * With thanks to CITI's project sponsor and partner, IBM.
+ */
+
+#ifndef _SIMPLE_RPC_PIPEFS_H_
+#define _SIMPLE_RPC_PIPEFS_H_
+
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/mount.h>
+#include <linux/sched.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/rpc_pipe_fs.h>
+
+
+#define payload_of(headerp) ((void *)(headerp + 1))
+
+/*
+ * pipefs_hdr_t -- the generic message format for simple_rpc_pipefs. Messages
+ * may simply be the header itself, although having an optional data payload
+ * follow the header allows much more flexibility.
+ *
+ * Messages are created using pipefs_alloc_init_msg() and
+ * pipefs_alloc_init_msg_padded(), both of which accept a pointer to an
+ * (optional) data payload.
+ *
+ * Given a pipefs_hdr_t *msg that has a struct foo payload, the data can be
+ * accessed using: struct foo *foop = payload_of(msg)
+ */
+typedef struct pipefs_hdr {
+ u32 msgid;
+ u8 type;
+ u8 flags;
+ u16 totallen; /* length of entire message, including hdr itself */
+ u32 status;
+} pipefs_hdr_t;
+
+/*
+ * pipefs_list_t -- a type of list used for tracking callers who've made an
+ * upcall and are blocked waiting for a reply.
+ *
+ * See pipefs_queue_upcall_waitreply() and pipefs_assign_upcall_reply().
+ */
+typedef struct pipefs_list {
+ struct list_head list;
+ spinlock_t list_lock;
+} pipefs_list_t;
+
+
+/* See net/sunrpc/simple_rpc_pipefs.c for more info on using these functions. */
+extern struct dentry* pipefs_mkpipe(const char *name, struct rpc_pipe_ops *ops, int wait_for_open);
+extern void pipefs_closepipe(struct dentry *pipe);
+extern void pipefs_init_list(pipefs_list_t *list);
+extern pipefs_hdr_t* pipefs_alloc_init_msg(u32 msgid, u8 type, u8 flags, void *data, u16 datalen);
+extern pipefs_hdr_t* pipefs_alloc_init_msg_padded(u32 msgid, u8 type, u8 flags, void *data, u16 datalen, u16 padlen);
+extern pipefs_hdr_t* pipefs_queue_upcall_waitreply(struct dentry *pipe, pipefs_hdr_t *msg, pipefs_list_t *uplist, u8 upflags, u32 timeout);
+extern int pipefs_queue_upcall_noreply(struct dentry *pipe, pipefs_hdr_t *msg, u8 upflags);
+extern int pipefs_assign_upcall_reply(pipefs_hdr_t *reply, pipefs_list_t *uplist);
+extern pipefs_hdr_t* pipefs_readmsg(struct file *filp, const char __user *src, size_t len);
+extern ssize_t pipefs_generic_upcall(struct file *filp, struct rpc_pipe_msg *rpcmsg, char __user *dst, size_t buflen);
+extern void pipefs_generic_destroy_msg(struct rpc_pipe_msg *rpcmsg);
+
+#endif /* _SIMPLE_RPC_PIPEFS_H_ */
diff --git a/net/sunrpc/Makefile b/net/sunrpc/Makefile
index db73fd2..bf44221 100644
--- a/net/sunrpc/Makefile
+++ b/net/sunrpc/Makefile
@@ -12,7 +12,7 @@ sunrpc-y := clnt.o xprt.o socklib.o xprtsock.o sched.o \
svc.o svcsock.o svcauth.o svcauth_unix.o \
rpcb_clnt.o timer.o xdr.o \
sunrpc_syms.o cache.o rpc_pipe.o \
- svc_xprt.o
+ svc_xprt.o simple_rpc_pipefs.o
sunrpc-$(CONFIG_NFS_V4_1) += backchannel_rqst.o bc_svc.o
sunrpc-$(CONFIG_PROC_FS) += stats.o
sunrpc-$(CONFIG_SYSCTL) += sysctl.o
diff --git a/net/sunrpc/simple_rpc_pipefs.c b/net/sunrpc/simple_rpc_pipefs.c
new file mode 100644
index 0000000..bd95958
--- /dev/null
+++ b/net/sunrpc/simple_rpc_pipefs.c
@@ -0,0 +1,424 @@
+/*
+ * net/sunrpc/simple_rpc_pipefs.c
+ *
+ * Copyright (c) 2008 The Regents of the University of Michigan.
+ * All rights reserved.
+ *
+ * David M. Richter <richterd@xxxxxxxxxxxxxx>
+ *
+ * Drawing on work done by Andy Adamson <andros@xxxxxxxxxxxxxx> and
+ * Marius Eriksen <marius@xxxxxxxxxx>. Thanks for the help over the
+ * years, guys.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * With thanks to CITI's project sponsor and partner, IBM.
+ */
+
+#include <linux/completion.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/sunrpc/simple_rpc_pipefs.h>
+
+
+/*
+ * Make an rpc_pipefs pipe named @name at the root of the mounted rpc_pipefs
+ * filesystem.
+ *
+ * If @wait_for_open is non-zero and an upcall is later queued but the userland
+ * end of the pipe has not yet been opened, the upcall will remain queued until
+ * the pipe is opened; otherwise, the upcall queueing will return with -EPIPE.
+ */
+struct dentry* pipefs_mkpipe(const char *name, struct rpc_pipe_ops *ops,
+ int wait_for_open)
+{
+ struct dentry *dir, *pipe;
+ struct vfsmount *mnt;
+
+ mnt = rpc_get_mount();
+ if (IS_ERR(mnt)) {
+ pipe = ERR_CAST(mnt);
+ goto out;
+ }
+ dir = mnt->mnt_root;
+ if (!dir) {
+ pipe = ERR_PTR(-ENOENT);
+ goto out;
+ }
+ pipe = rpc_mkpipe(dir, name, NULL, ops,
+ wait_for_open ? RPC_PIPE_WAIT_FOR_OPEN : 0);
+out:
+ return pipe;
+}
+EXPORT_SYMBOL(pipefs_mkpipe);
+
+/*
+ * Shutdown a pipe made by pipefs_mkpipe().
+ * XXX: do we need to retain an extra reference on the mount?
+ */
+void pipefs_closepipe(struct dentry *pipe)
+{
+ rpc_unlink(pipe);
+ rpc_put_mount();
+}
+EXPORT_SYMBOL(pipefs_closepipe);
+
+/*
+ * Initialize a pipefs_list_t -- which are a way to keep track of callers
+ * who're blocked having made an upcall and are awaiting a reply.
+ *
+ * See pipefs_queue_upcall_waitreply() and pipefs_find_upcall_msgid() for how
+ * to use them.
+ */
+inline void pipefs_init_list(pipefs_list_t *list)
+{
+ INIT_LIST_HEAD(&list->list);
+ spin_lock_init(&list->list_lock);
+}
+EXPORT_SYMBOL(pipefs_init_list);
+
+/*
+ * Alloc/init a generic pipefs message header and copy into its message body
+ * an arbitrary data payload.
+ *
+ * pipefs_hdr_t's are meant to serve as generic, general-purpose message
+ * headers for easy rpc_pipefs I/O. When an upcall is made, the
+ * pipefs_hdr_t is assigned to a struct rpc_pipe_msg and delivered
+ * therein. --And yes, the naming can seem a little confusing at first:
+ *
+ * When one thinks of an upcall "message", in simple_rpc_pipefs that's a
+ * pipefs_hdr_t (possibly with an attached message body). A
+ * struct rpc_pipe_msg is actually only the -vehicle- by which the "real"
+ * message is delivered and processed.
+ */
+pipefs_hdr_t* pipefs_alloc_init_msg_padded(u32 msgid, u8 type, u8 flags,
+ void *data, u16 datalen, u16 padlen)
+{
+ u16 totallen;
+ pipefs_hdr_t *msg = NULL;
+
+ totallen = sizeof(*msg) + datalen + padlen;
+ if (totallen > PAGE_SIZE) {
+ msg = ERR_PTR(-E2BIG);
+ goto out;
+ }
+
+ msg = kzalloc(totallen, GFP_KERNEL);
+ if (!msg) {
+ msg = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ msg->msgid = msgid;
+ msg->type = type;
+ msg->flags = flags;
+ msg->totallen = totallen;
+ memcpy(payload_of(msg), data, datalen);
+out:
+ return msg;
+}
+EXPORT_SYMBOL(pipefs_alloc_init_msg_padded);
+
+/*
+ * See the description of pipefs_alloc_init_msg_padded().
+ */
+pipefs_hdr_t* pipefs_alloc_init_msg(u32 msgid, u8 type, u8 flags,
+ void *data, u16 datalen)
+{
+ return pipefs_alloc_init_msg_padded(msgid, type, flags, data,
+ datalen, 0);
+}
+EXPORT_SYMBOL(pipefs_alloc_init_msg);
+
+
+static void pipefs_init_rpcmsg(struct rpc_pipe_msg *rpcmsg, pipefs_hdr_t *msg,
+ u8 upflags)
+{
+ memset(rpcmsg, 0, sizeof(*rpcmsg));
+ rpcmsg->data = msg;
+ rpcmsg->len = msg->totallen;
+ rpcmsg->flags = upflags;
+}
+
+static struct rpc_pipe_msg* pipefs_alloc_init_rpcmsg(pipefs_hdr_t *msg,
+ u8 upflags)
+{
+ struct rpc_pipe_msg *rpcmsg;
+
+ rpcmsg = kmalloc(sizeof(*rpcmsg), GFP_KERNEL);
+ if (!rpcmsg)
+ return ERR_PTR(-ENOMEM);
+
+ pipefs_init_rpcmsg(rpcmsg, msg, upflags);
+ return rpcmsg;
+}
+
+
+/* represents an upcall that'll block and wait for a reply */
+typedef struct pipefs_upcall {
+ u32 msgid;
+ struct rpc_pipe_msg rpcmsg;
+ struct list_head list;
+ wait_queue_head_t waitq;
+ struct pipefs_hdr *reply;
+} pipefs_upcall_t;
+
+
+static void pipefs_init_upcall_waitreply(pipefs_upcall_t *upcall,
+ pipefs_hdr_t *msg, u8 upflags)
+{
+ upcall->reply = NULL;
+ upcall->msgid = msg->msgid;
+ INIT_LIST_HEAD(&upcall->list);
+ init_waitqueue_head(&upcall->waitq);
+ pipefs_init_rpcmsg(&upcall->rpcmsg, msg, upflags);
+}
+
+static int __pipefs_queue_upcall_waitreply(struct dentry *pipe,
+ pipefs_upcall_t *upcall,
+ pipefs_list_t *uplist, u32 timeout)
+{
+ int err = 0;
+ DECLARE_WAITQUEUE(wq, current);
+
+ add_wait_queue(&upcall->waitq, &wq);
+ spin_lock(&uplist->list_lock);
+ list_add(&upcall->list, &uplist->list);
+ spin_unlock(&uplist->list_lock);
+
+ err = rpc_queue_upcall(pipe->d_inode, &upcall->rpcmsg);
+ if (err < 0)
+ goto out;
+
+ if (timeout) {
+ /* retval of 0 means timer expired */
+ err = schedule_timeout_uninterruptible(timeout);
+ if (err == 0 && upcall->reply == NULL)
+ err = -ETIMEDOUT;
+ } else {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule();
+ __set_current_state(TASK_RUNNING);
+ }
+
+ spin_lock(&uplist->list_lock);
+ list_del_init(&upcall->list);
+ spin_unlock(&uplist->list_lock);
+ remove_wait_queue(&upcall->waitq, &wq);
+out:
+ return err;
+}
+
+/*
+ * Queue a pipefs msg for an upcall to userspace, place the calling thread
+ * on @uplist, and block the thread to wait for a reply. If @timeout is
+ * nonzero, the thread will be blocked for at most @timeout jiffies.
+ *
+ * (To convert time units into jiffies, consider the functions
+ * msecs_to_jiffies(), usecs_to_jiffies(), timeval_to_jiffies(), and
+ * timespec_to_jiffies().)
+ *
+ * Once a reply is received by your downcall handler, call
+ * pipefs_assign_upcall_reply() with @uplist to find the corresponding upcall,
+ * assign the reply, and wake the waiting thread.
+ *
+ * This function's return value pointer may be an error and should be checked
+ * with IS_ERR() before attempting to access the reply message.
+ *
+ * Callers are responsible for freeing @msg, unless pipefs_generic_destroy_msg()
+ * is used as the ->destroy_msg() callback and the PIPEFS_AUTOFREE_UPCALL_MSG
+ * flag is set in @upflags. See also rpc_pipe_fs.h.
+ */
+pipefs_hdr_t* pipefs_queue_upcall_waitreply(struct dentry *pipe,
+ pipefs_hdr_t *msg,
+ pipefs_list_t *uplist,
+ u8 upflags, u32 timeout)
+{
+ int err = 0;
+ pipefs_upcall_t upcall;
+
+ pipefs_init_upcall_waitreply(&upcall, msg, upflags);
+ err = __pipefs_queue_upcall_waitreply(pipe, &upcall, uplist, timeout);
+ if (err) {
+ kfree(upcall.reply);
+ upcall.reply = ERR_PTR(err);
+ }
+
+ return upcall.reply;
+}
+EXPORT_SYMBOL(pipefs_queue_upcall_waitreply);
+
+/*
+ * Queue a pipefs msg for an upcall to userspace and immediately return (i.e.,
+ * no reply is expected).
+ *
+ * Callers are responsible for freeing @msg, unless pipefs_generic_destroy_msg()
+ * is used as the ->destroy_msg() callback and the PIPEFS_AUTOFREE_UPCALL_MSG
+ * flag is set in @upflags. See also rpc_pipe_fs.h.
+ */
+int pipefs_queue_upcall_noreply(struct dentry *pipe, pipefs_hdr_t *msg,
+ u8 upflags)
+{
+ int err = 0;
+ struct rpc_pipe_msg *rpcmsg;
+
+ upflags |= PIPEFS_AUTOFREE_RPCMSG;
+ rpcmsg = pipefs_alloc_init_rpcmsg(msg, upflags);
+ if (IS_ERR(rpcmsg)) {
+ err = PTR_ERR(rpcmsg);
+ goto out;
+ }
+ err = rpc_queue_upcall(pipe->d_inode, rpcmsg);
+out:
+ return err;
+}
+EXPORT_SYMBOL(pipefs_queue_upcall_noreply);
+
+
+static pipefs_upcall_t* pipefs_find_upcall_msgid(u32 msgid,
+ pipefs_list_t *uplist)
+{
+ pipefs_upcall_t *upcall;
+
+ spin_lock(&uplist->list_lock);
+ list_for_each_entry(upcall, &uplist->list, list)
+ if (upcall->msgid == msgid)
+ goto out;
+ upcall = NULL;
+out:
+ spin_unlock(&uplist->list_lock);
+ return upcall;
+}
+
+/*
+ * In your rpc_pipe_ops->downcall() handler, once you've read in a downcall
+ * message and have determined that it is a reply to a waiting upcall,
+ * you can use this function to find the appropriate upcall, assign the result,
+ * and wake the upcall thread.
+ *
+ * The reply message must have the same msgid as the original upcall message's.
+ *
+ * See also pipefs_queue_upcall_waitreply() and pipefs_readmsg().
+ */
+int pipefs_assign_upcall_reply(pipefs_hdr_t *reply, pipefs_list_t *uplist)
+{
+ int err = 0;
+ pipefs_upcall_t *upcall;
+
+ upcall = pipefs_find_upcall_msgid(reply->msgid, uplist);
+ if (!upcall) {
+ printk(KERN_ERR "%s: ERROR: have reply but no matching upcall "
+ "for msgid %d\n", __func__, reply->msgid);
+ err = -ENOENT;
+ goto out;
+ }
+ upcall->reply = reply;
+ wake_up(&upcall->waitq);
+out:
+ return err;
+}
+EXPORT_SYMBOL(pipefs_assign_upcall_reply);
+
+/*
+ * Generic method to read-in and return a newly-allocated message which begins
+ * with a pipefs_hdr_t.
+ */
+pipefs_hdr_t* pipefs_readmsg(struct file *filp, const char __user *src,
+ size_t len)
+{
+ int err = 0, hdrsize;
+ pipefs_hdr_t *msg = NULL;
+
+ hdrsize = sizeof(*msg);
+ if (len < hdrsize) {
+ printk(KERN_ERR "%s: ERROR: header is too short (%d vs %d)\n",
+ __func__, len, hdrsize);
+ err = -EINVAL;
+ goto out;
+ }
+
+ msg = kzalloc(len, GFP_KERNEL);
+ if (!msg) {
+ err = -ENOMEM;
+ goto out;
+ }
+ if (copy_from_user(msg, src, len))
+ err = -EFAULT;
+out:
+ if (err) {
+ if (msg)
+ kfree(msg);
+ msg = ERR_PTR(err);
+ }
+ return msg;
+}
+EXPORT_SYMBOL(pipefs_readmsg);
+
+/*
+ * Generic rpc_pipe_ops->upcall() handler implementation.
+ *
+ * Don't call this directly: to make an upcall, use
+ * pipefs_queue_upcall_waitreply() or pipefs_queue_upcall_noreply().
+ */
+ssize_t pipefs_generic_upcall(struct file *filp, struct rpc_pipe_msg *rpcmsg,
+ char __user *dst, size_t buflen)
+{
+ char *data;
+ ssize_t len, left;
+
+ data = (char *)rpcmsg->data + rpcmsg->copied;
+ len = rpcmsg->len - rpcmsg->copied;
+ if (len > buflen)
+ len = buflen;
+
+ left = copy_to_user(dst, data, len);
+ if (left < 0) {
+ rpcmsg->errno = left;
+ return left;
+ }
+
+ len -= left;
+ rpcmsg->copied += len;
+ rpcmsg->errno = 0;
+ return len;
+}
+EXPORT_SYMBOL(pipefs_generic_upcall);
+
+/*
+ * Generic rpc_pipe_ops->destroy_msg() handler implementation.
+ *
+ * Items are only freed if @rpcmsg->flags has been set appropriately.
+ * See pipefs_queue_upcall_noreply() and rpc_pipe_fs.h.
+ */
+void pipefs_generic_destroy_msg(struct rpc_pipe_msg *rpcmsg)
+{
+ if (rpcmsg->flags & PIPEFS_AUTOFREE_UPCALL_MSG)
+ kfree(rpcmsg->data);
+ if (rpcmsg->flags & PIPEFS_AUTOFREE_RPCMSG)
+ kfree(rpcmsg);
+}
+EXPORT_SYMBOL(pipefs_generic_destroy_msg);
+
--
1.5.4
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