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![Nicholas Mc Guire](/assets/img/avatar_default.png)
Return type of wait_for_completion_timeout() is unsigned long not int. An appropriately named unsigned long is added and the assignment fixed. Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
287 lines
7.1 KiB
C
287 lines
7.1 KiB
C
/*
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* Copyright (C) 2006-2009 Red Hat, Inc.
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*
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* This file is released under the LGPL.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <net/sock.h>
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#include <linux/workqueue.h>
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#include <linux/connector.h>
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#include <linux/device-mapper.h>
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#include <linux/dm-log-userspace.h>
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#include "dm-log-userspace-transfer.h"
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static uint32_t dm_ulog_seq;
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/*
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* Netlink/Connector is an unreliable protocol. How long should
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* we wait for a response before assuming it was lost and retrying?
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* (If we do receive a response after this time, it will be discarded
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* and the response to the resent request will be waited for.
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*/
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#define DM_ULOG_RETRY_TIMEOUT (15 * HZ)
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/*
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* Pre-allocated space for speed
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*/
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#define DM_ULOG_PREALLOCED_SIZE 512
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static struct cn_msg *prealloced_cn_msg;
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static struct dm_ulog_request *prealloced_ulog_tfr;
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static struct cb_id ulog_cn_id = {
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.idx = CN_IDX_DM,
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.val = CN_VAL_DM_USERSPACE_LOG
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};
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static DEFINE_MUTEX(dm_ulog_lock);
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struct receiving_pkg {
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struct list_head list;
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struct completion complete;
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uint32_t seq;
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int error;
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size_t *data_size;
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char *data;
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};
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static DEFINE_SPINLOCK(receiving_list_lock);
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static struct list_head receiving_list;
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static int dm_ulog_sendto_server(struct dm_ulog_request *tfr)
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{
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int r;
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struct cn_msg *msg = prealloced_cn_msg;
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memset(msg, 0, sizeof(struct cn_msg));
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msg->id.idx = ulog_cn_id.idx;
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msg->id.val = ulog_cn_id.val;
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msg->ack = 0;
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msg->seq = tfr->seq;
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msg->len = sizeof(struct dm_ulog_request) + tfr->data_size;
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r = cn_netlink_send(msg, 0, 0, gfp_any());
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return r;
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}
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/*
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* Parameters for this function can be either msg or tfr, but not
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* both. This function fills in the reply for a waiting request.
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* If just msg is given, then the reply is simply an ACK from userspace
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* that the request was received.
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*
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* Returns: 0 on success, -ENOENT on failure
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*/
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static int fill_pkg(struct cn_msg *msg, struct dm_ulog_request *tfr)
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{
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uint32_t rtn_seq = (msg) ? msg->seq : (tfr) ? tfr->seq : 0;
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struct receiving_pkg *pkg;
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/*
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* The 'receiving_pkg' entries in this list are statically
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* allocated on the stack in 'dm_consult_userspace'.
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* Each process that is waiting for a reply from the user
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* space server will have an entry in this list.
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*
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* We are safe to do it this way because the stack space
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* is unique to each process, but still addressable by
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* other processes.
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*/
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list_for_each_entry(pkg, &receiving_list, list) {
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if (rtn_seq != pkg->seq)
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continue;
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if (msg) {
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pkg->error = -msg->ack;
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/*
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* If we are trying again, we will need to know our
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* storage capacity. Otherwise, along with the
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* error code, we make explicit that we have no data.
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*/
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if (pkg->error != -EAGAIN)
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*(pkg->data_size) = 0;
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} else if (tfr->data_size > *(pkg->data_size)) {
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DMERR("Insufficient space to receive package [%u] "
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"(%u vs %zu)", tfr->request_type,
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tfr->data_size, *(pkg->data_size));
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*(pkg->data_size) = 0;
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pkg->error = -ENOSPC;
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} else {
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pkg->error = tfr->error;
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memcpy(pkg->data, tfr->data, tfr->data_size);
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*(pkg->data_size) = tfr->data_size;
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}
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complete(&pkg->complete);
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return 0;
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}
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return -ENOENT;
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}
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/*
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* This is the connector callback that delivers data
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* that was sent from userspace.
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*/
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static void cn_ulog_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
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{
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struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
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if (!capable(CAP_SYS_ADMIN))
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return;
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spin_lock(&receiving_list_lock);
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if (msg->len == 0)
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fill_pkg(msg, NULL);
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else if (msg->len < sizeof(*tfr))
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DMERR("Incomplete message received (expected %u, got %u): [%u]",
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(unsigned)sizeof(*tfr), msg->len, msg->seq);
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else
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fill_pkg(NULL, tfr);
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spin_unlock(&receiving_list_lock);
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}
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/**
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* dm_consult_userspace
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* @uuid: log's universal unique identifier (must be DM_UUID_LEN in size)
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* @luid: log's local unique identifier
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* @request_type: found in include/linux/dm-log-userspace.h
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* @data: data to tx to the server
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* @data_size: size of data in bytes
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* @rdata: place to put return data from server
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* @rdata_size: value-result (amount of space given/amount of space used)
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*
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* rdata_size is undefined on failure.
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*
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* Memory used to communicate with userspace is zero'ed
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* before populating to ensure that no unwanted bits leak
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* from kernel space to user-space. All userspace log communications
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* between kernel and user space go through this function.
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*
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* Returns: 0 on success, -EXXX on failure
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**/
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int dm_consult_userspace(const char *uuid, uint64_t luid, int request_type,
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char *data, size_t data_size,
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char *rdata, size_t *rdata_size)
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{
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int r = 0;
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unsigned long tmo;
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size_t dummy = 0;
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int overhead_size = sizeof(struct dm_ulog_request) + sizeof(struct cn_msg);
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struct dm_ulog_request *tfr = prealloced_ulog_tfr;
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struct receiving_pkg pkg;
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/*
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* Given the space needed to hold the 'struct cn_msg' and
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* 'struct dm_ulog_request' - do we have enough payload
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* space remaining?
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*/
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if (data_size > (DM_ULOG_PREALLOCED_SIZE - overhead_size)) {
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DMINFO("Size of tfr exceeds preallocated size");
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return -EINVAL;
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}
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if (!rdata_size)
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rdata_size = &dummy;
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resend:
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/*
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* We serialize the sending of requests so we can
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* use the preallocated space.
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*/
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mutex_lock(&dm_ulog_lock);
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memset(tfr, 0, DM_ULOG_PREALLOCED_SIZE - sizeof(struct cn_msg));
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memcpy(tfr->uuid, uuid, DM_UUID_LEN);
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tfr->version = DM_ULOG_REQUEST_VERSION;
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tfr->luid = luid;
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tfr->seq = dm_ulog_seq++;
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/*
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* Must be valid request type (all other bits set to
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* zero). This reserves other bits for possible future
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* use.
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*/
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tfr->request_type = request_type & DM_ULOG_REQUEST_MASK;
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tfr->data_size = data_size;
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if (data && data_size)
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memcpy(tfr->data, data, data_size);
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memset(&pkg, 0, sizeof(pkg));
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init_completion(&pkg.complete);
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pkg.seq = tfr->seq;
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pkg.data_size = rdata_size;
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pkg.data = rdata;
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spin_lock(&receiving_list_lock);
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list_add(&(pkg.list), &receiving_list);
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spin_unlock(&receiving_list_lock);
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r = dm_ulog_sendto_server(tfr);
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mutex_unlock(&dm_ulog_lock);
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if (r) {
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DMERR("Unable to send log request [%u] to userspace: %d",
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request_type, r);
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spin_lock(&receiving_list_lock);
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list_del_init(&(pkg.list));
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spin_unlock(&receiving_list_lock);
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goto out;
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}
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tmo = wait_for_completion_timeout(&(pkg.complete), DM_ULOG_RETRY_TIMEOUT);
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spin_lock(&receiving_list_lock);
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list_del_init(&(pkg.list));
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spin_unlock(&receiving_list_lock);
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if (!tmo) {
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DMWARN("[%s] Request timed out: [%u/%u] - retrying",
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(strlen(uuid) > 8) ?
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(uuid + (strlen(uuid) - 8)) : (uuid),
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request_type, pkg.seq);
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goto resend;
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}
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r = pkg.error;
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if (r == -EAGAIN)
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goto resend;
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out:
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return r;
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}
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int dm_ulog_tfr_init(void)
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{
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int r;
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void *prealloced;
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INIT_LIST_HEAD(&receiving_list);
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prealloced = kmalloc(DM_ULOG_PREALLOCED_SIZE, GFP_KERNEL);
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if (!prealloced)
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return -ENOMEM;
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prealloced_cn_msg = prealloced;
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prealloced_ulog_tfr = prealloced + sizeof(struct cn_msg);
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r = cn_add_callback(&ulog_cn_id, "dmlogusr", cn_ulog_callback);
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if (r) {
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kfree(prealloced_cn_msg);
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return r;
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}
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return 0;
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}
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void dm_ulog_tfr_exit(void)
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{
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cn_del_callback(&ulog_cn_id);
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kfree(prealloced_cn_msg);
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}
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