[linux-2.6-block.git] / net / sunrpc / backchannel_rqst.c

/******************************************************************************

(c) 2007 Network Appliance, Inc.  All Rights Reserved.
(c) 2009 NetApp.  All Rights Reserved.

NetApp provides this source code under the GPL v2 License.
The GPL v2 license is available at
http://opensource.org/licenses/gpl-license.php.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"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 COPYRIGHT OWNER 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.

******************************************************************************/

#include <linux/tcp.h>
#include <linux/slab.h>
#include <linux/sunrpc/xprt.h>
#include <linux/export.h>
#include <linux/sunrpc/bc_xprt.h>

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
#define RPCDBG_FACILITY	RPCDBG_TRANS
#endif

/*
 * Helper routines that track the number of preallocation elements
 * on the transport.
 */
static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
{
	return xprt->bc_alloc_count < atomic_read(&xprt->bc_free_slots);
}

static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
{
	atomic_add(n, &xprt->bc_free_slots);
	xprt->bc_alloc_count += n;
}

static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
{
	atomic_sub(n, &xprt->bc_free_slots);
	return xprt->bc_alloc_count -= n;
}

/*
 * Free the preallocated rpc_rqst structure and the memory
 * buffers hanging off of it.
 */
static void xprt_free_allocation(struct rpc_rqst *req)
{
	struct xdr_buf *xbufp;

	dprintk("RPC:        free allocations for req= %p\n", req);
	WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
	xbufp = &req->rq_rcv_buf;
	free_page((unsigned long)xbufp->head[0].iov_base);
	xbufp = &req->rq_snd_buf;
	free_page((unsigned long)xbufp->head[0].iov_base);
	kfree(req);
}

static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
{
	struct page *page;
	/* Preallocate one XDR receive buffer */
	page = alloc_page(gfp_flags);
	if (page == NULL)
		return -ENOMEM;
	buf->head[0].iov_base = page_address(page);
	buf->head[0].iov_len = PAGE_SIZE;
	buf->tail[0].iov_base = NULL;
	buf->tail[0].iov_len = 0;
	buf->page_len = 0;
	buf->len = 0;
	buf->buflen = PAGE_SIZE;
	return 0;
}

static
struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
{
	struct rpc_rqst *req;

	/* Pre-allocate one backchannel rpc_rqst */
	req = kzalloc(sizeof(*req), gfp_flags);
	if (req == NULL)
		return NULL;

	req->rq_xprt = xprt;
	INIT_LIST_HEAD(&req->rq_list);
	INIT_LIST_HEAD(&req->rq_bc_list);

	/* Preallocate one XDR receive buffer */
	if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
		printk(KERN_ERR "Failed to create bc receive xbuf\n");
		goto out_free;
	}
	req->rq_rcv_buf.len = PAGE_SIZE;

	/* Preallocate one XDR send buffer */
	if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
		printk(KERN_ERR "Failed to create bc snd xbuf\n");
		goto out_free;
	}
	return req;
out_free:
	xprt_free_allocation(req);
	return NULL;
}

/*
 * Preallocate up to min_reqs structures and related buffers for use
 * by the backchannel.  This function can be called multiple times
 * when creating new sessions that use the same rpc_xprt.  The
 * preallocated buffers are added to the pool of resources used by
 * the rpc_xprt.  Anyone of these resources may be used used by an
 * incoming callback request.  It's up to the higher levels in the
 * stack to enforce that the maximum number of session slots is not
 * being exceeded.
 *
 * Some callback arguments can be large.  For example, a pNFS server
 * using multiple deviceids.  The list can be unbound, but the client
 * has the ability to tell the server the maximum size of the callback
 * requests.  Each deviceID is 16 bytes, so allocate one page
 * for the arguments to have enough room to receive a number of these
 * deviceIDs.  The NFS client indicates to the pNFS server that its
 * callback requests can be up to 4096 bytes in size.
 */
int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
{
	struct rpc_rqst *req;
	struct list_head tmp_list;
	int i;

	dprintk("RPC:       setup backchannel transport\n");

	/*
	 * We use a temporary list to keep track of the preallocated
	 * buffers.  Once we're done building the list we splice it
	 * into the backchannel preallocation list off of the rpc_xprt
	 * struct.  This helps minimize the amount of time the list
	 * lock is held on the rpc_xprt struct.  It also makes cleanup
	 * easier in case of memory allocation errors.
	 */
	INIT_LIST_HEAD(&tmp_list);
	for (i = 0; i < min_reqs; i++) {
		/* Pre-allocate one backchannel rpc_rqst */
		req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
		if (req == NULL) {
			printk(KERN_ERR "Failed to create bc rpc_rqst\n");
			goto out_free;
		}

		/* Add the allocated buffer to the tmp list */
		dprintk("RPC:       adding req= %p\n", req);
		list_add(&req->rq_bc_pa_list, &tmp_list);
	}

	/*
	 * Add the temporary list to the backchannel preallocation list
	 */
	spin_lock_bh(&xprt->bc_pa_lock);
	list_splice(&tmp_list, &xprt->bc_pa_list);
	xprt_inc_alloc_count(xprt, min_reqs);
	spin_unlock_bh(&xprt->bc_pa_lock);

	dprintk("RPC:       setup backchannel transport done\n");
	return 0;

out_free:
	/*
	 * Memory allocation failed, free the temporary list
	 */
	while (!list_empty(&tmp_list)) {
		req = list_first_entry(&tmp_list,
				struct rpc_rqst,
				rq_bc_pa_list);
		list_del(&req->rq_bc_pa_list);
		xprt_free_allocation(req);
	}

	dprintk("RPC:       setup backchannel transport failed\n");
	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(xprt_setup_backchannel);

/**
 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
 * @xprt:	the transport holding the preallocated strucures
 * @max_reqs	the maximum number of preallocated structures to destroy
 *
 * Since these structures may have been allocated by multiple calls
 * to xprt_setup_backchannel, we only destroy up to the maximum number
 * of reqs specified by the caller.
 */
void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
{
	struct rpc_rqst *req = NULL, *tmp = NULL;

	dprintk("RPC:        destroy backchannel transport\n");

	if (max_reqs == 0)
		goto out;

	spin_lock_bh(&xprt->bc_pa_lock);
	xprt_dec_alloc_count(xprt, max_reqs);
	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
		dprintk("RPC:        req=%p\n", req);
		list_del(&req->rq_bc_pa_list);
		xprt_free_allocation(req);
		if (--max_reqs == 0)
			break;
	}
	spin_unlock_bh(&xprt->bc_pa_lock);

out:
	dprintk("RPC:        backchannel list empty= %s\n",
		list_empty(&xprt->bc_pa_list) ? "true" : "false");
}
EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);

static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid)
{
	struct rpc_rqst *req = NULL;

	dprintk("RPC:       allocate a backchannel request\n");
	if (atomic_read(&xprt->bc_free_slots) <= 0)
		goto not_found;
	if (list_empty(&xprt->bc_pa_list)) {
		req = xprt_alloc_bc_req(xprt, GFP_ATOMIC);
		if (!req)
			goto not_found;
		/* Note: this 'free' request adds it to xprt->bc_pa_list */
		xprt_free_bc_request(req);
	}
	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
				rq_bc_pa_list);
	req->rq_reply_bytes_recvd = 0;
	req->rq_bytes_sent = 0;
	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
			sizeof(req->rq_private_buf));
	req->rq_xid = xid;
	req->rq_connect_cookie = xprt->connect_cookie;
not_found:
	dprintk("RPC:       backchannel req=%p\n", req);
	return req;
}

/*
 * Return the preallocated rpc_rqst structure and XDR buffers
 * associated with this rpc_task.
 */
void xprt_free_bc_request(struct rpc_rqst *req)
{
	struct rpc_xprt *xprt = req->rq_xprt;

	dprintk("RPC:       free backchannel req=%p\n", req);

	req->rq_connect_cookie = xprt->connect_cookie - 1;
	smp_mb__before_atomic();
	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	smp_mb__after_atomic();

	/*
	 * Return it to the list of preallocations so that it
	 * may be reused by a new callback request.
	 */
	spin_lock_bh(&xprt->bc_pa_lock);
	if (xprt_need_to_requeue(xprt)) {
		list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
		xprt->bc_alloc_count++;
		req = NULL;
	}
	spin_unlock_bh(&xprt->bc_pa_lock);
	if (req != NULL) {
		/*
		 * The last remaining session was destroyed while this
		 * entry was in use.  Free the entry and don't attempt
		 * to add back to the list because there is no need to
		 * have anymore preallocated entries.
		 */
		dprintk("RPC:       Last session removed req=%p\n", req);
		xprt_free_allocation(req);
		return;
	}
}

/*
 * One or more rpc_rqst structure have been preallocated during the
 * backchannel setup.  Buffer space for the send and private XDR buffers
 * has been preallocated as well.  Use xprt_alloc_bc_request to allocate
 * to this request.  Use xprt_free_bc_request to return it.
 *
 * We know that we're called in soft interrupt context, grab the spin_lock
 * since there is no need to grab the bottom half spin_lock.
 *
 * Return an available rpc_rqst, otherwise NULL if non are available.
 */
struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
{
	struct rpc_rqst *req;

	spin_lock(&xprt->bc_pa_lock);
	list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
		if (req->rq_connect_cookie != xprt->connect_cookie)
			continue;
		if (req->rq_xid == xid)
			goto found;
	}
	req = xprt_alloc_bc_request(xprt, xid);
found:
	spin_unlock(&xprt->bc_pa_lock);
	return req;
}

/*
 * Add callback request to callback list.  The callback
 * service sleeps on the sv_cb_waitq waiting for new
 * requests.  Wake it up after adding enqueing the
 * request.
 */
void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
{
	struct rpc_xprt *xprt = req->rq_xprt;
	struct svc_serv *bc_serv = xprt->bc_serv;

	spin_lock(&xprt->bc_pa_lock);
	list_del(&req->rq_bc_pa_list);
	xprt->bc_alloc_count--;
	spin_unlock(&xprt->bc_pa_lock);

	req->rq_private_buf.len = copied;
	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);

	dprintk("RPC:       add callback request to list\n");
	spin_lock(&bc_serv->sv_cb_lock);
	list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
	wake_up(&bc_serv->sv_cb_waitq);
	spin_unlock(&bc_serv->sv_cb_lock);
}
Commit	Line	Data
fb7a0b9a RL	1	/******************************************************************************
	2
	3	(c) 2007 Network Appliance, Inc. All Rights Reserved.
	4	(c) 2009 NetApp. All Rights Reserved.
	5
	6	NetApp provides this source code under the GPL v2 License.
	7	The GPL v2 license is available at
	8	http://opensource.org/licenses/gpl-license.php.
	9
	10	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	11	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	12	LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	13	A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	14	CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	15	EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	16	PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	17	PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
	18	LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
	19	NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	20	SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	21
	22	******************************************************************************/
	23
	24	#include <linux/tcp.h>
5a0e3ad6	25	#include <linux/slab.h>
fb7a0b9a	26	#include <linux/sunrpc/xprt.h>
bc3b2d7f	27	#include <linux/export.h>
09acfea5	28	#include <linux/sunrpc/bc_xprt.h>
fb7a0b9a	29
f895b252	30	#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
fb7a0b9a RL	31	#define RPCDBG_FACILITY RPCDBG_TRANS
	32	#endif
	33
fb7a0b9a RL	34	/*
	35	* Helper routines that track the number of preallocation elements
	36	* on the transport.
	37	*/
	38	static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
	39	{
0d2a970d	40	return xprt->bc_alloc_count < atomic_read(&xprt->bc_free_slots);
fb7a0b9a RL	41	}
	42
	43	static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
	44	{
0d2a970d	45	atomic_add(n, &xprt->bc_free_slots);
fb7a0b9a RL	46	xprt->bc_alloc_count += n;
	47	}
	48
	49	static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
	50	{
0d2a970d	51	atomic_sub(n, &xprt->bc_free_slots);
fb7a0b9a RL	52	return xprt->bc_alloc_count -= n;
	53	}
	54
	55	/*
	56	* Free the preallocated rpc_rqst structure and the memory
	57	* buffers hanging off of it.
	58	*/
	59	static void xprt_free_allocation(struct rpc_rqst *req)
	60	{
	61	struct xdr_buf *xbufp;
	62
	63	dprintk("RPC: free allocations for req= %p\n", req);
f30dfbba	64	WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
88de6af2	65	xbufp = &req->rq_rcv_buf;
fb7a0b9a RL	66	free_page((unsigned long)xbufp->head[0].iov_base);
	67	xbufp = &req->rq_snd_buf;
	68	free_page((unsigned long)xbufp->head[0].iov_base);
fb7a0b9a RL	69	kfree(req);
	70	}
	71
1dddda86 TM	72	static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
	73	{
	74	struct page *page;
	75	/* Preallocate one XDR receive buffer */
	76	page = alloc_page(gfp_flags);
	77	if (page == NULL)
	78	return -ENOMEM;
	79	buf->head[0].iov_base = page_address(page);
	80	buf->head[0].iov_len = PAGE_SIZE;
	81	buf->tail[0].iov_base = NULL;
	82	buf->tail[0].iov_len = 0;
	83	buf->page_len = 0;
	84	buf->len = 0;
	85	buf->buflen = PAGE_SIZE;
	86	return 0;
	87	}
	88
	89	static
	90	struct rpc_rqst xprt_alloc_bc_req(struct rpc_xprt xprt, gfp_t gfp_flags)
	91	{
	92	struct rpc_rqst *req;
	93
	94	/* Pre-allocate one backchannel rpc_rqst */
	95	req = kzalloc(sizeof(*req), gfp_flags);
	96	if (req == NULL)
	97	return NULL;
	98
	99	req->rq_xprt = xprt;
	100	INIT_LIST_HEAD(&req->rq_list);
	101	INIT_LIST_HEAD(&req->rq_bc_list);
	102
	103	/* Preallocate one XDR receive buffer */
	104	if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
	105	printk(KERN_ERR "Failed to create bc receive xbuf\n");
	106	goto out_free;
	107	}
	108	req->rq_rcv_buf.len = PAGE_SIZE;
	109
	110	/* Preallocate one XDR send buffer */
	111	if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
	112	printk(KERN_ERR "Failed to create bc snd xbuf\n");
	113	goto out_free;
	114	}
	115	return req;
	116	out_free:
	117	xprt_free_allocation(req);
	118	return NULL;
	119	}
	120
fb7a0b9a RL	121	/*
	122	* Preallocate up to min_reqs structures and related buffers for use
	123	* by the backchannel. This function can be called multiple times
	124	* when creating new sessions that use the same rpc_xprt. The
	125	* preallocated buffers are added to the pool of resources used by
	126	* the rpc_xprt. Anyone of these resources may be used used by an
	127	* incoming callback request. It's up to the higher levels in the
	128	* stack to enforce that the maximum number of session slots is not
	129	* being exceeded.
	130	*
	131	* Some callback arguments can be large. For example, a pNFS server
	132	* using multiple deviceids. The list can be unbound, but the client
	133	* has the ability to tell the server the maximum size of the callback
	134	* requests. Each deviceID is 16 bytes, so allocate one page
	135	* for the arguments to have enough room to receive a number of these
	136	* deviceIDs. The NFS client indicates to the pNFS server that its
	137	* callback requests can be up to 4096 bytes in size.
	138	*/
	139	int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
	140	{
1dddda86	141	struct rpc_rqst *req;
fb7a0b9a RL	142	struct list_head tmp_list;
	143	int i;
	144
	145	dprintk("RPC: setup backchannel transport\n");
	146
	147	/*
	148	* We use a temporary list to keep track of the preallocated
	149	* buffers. Once we're done building the list we splice it
	150	* into the backchannel preallocation list off of the rpc_xprt
	151	* struct. This helps minimize the amount of time the list
	152	* lock is held on the rpc_xprt struct. It also makes cleanup
	153	* easier in case of memory allocation errors.
	154	*/
	155	INIT_LIST_HEAD(&tmp_list);
	156	for (i = 0; i < min_reqs; i++) {
	157	/* Pre-allocate one backchannel rpc_rqst */
1dddda86	158	req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
fb7a0b9a RL	159	if (req == NULL) {
	160	printk(KERN_ERR "Failed to create bc rpc_rqst\n");
	161	goto out_free;
	162	}
	163
	164	/* Add the allocated buffer to the tmp list */
	165	dprintk("RPC: adding req= %p\n", req);
	166	list_add(&req->rq_bc_pa_list, &tmp_list);
fb7a0b9a RL	167	}
	168
	169	/*
	170	* Add the temporary list to the backchannel preallocation list
	171	*/
	172	spin_lock_bh(&xprt->bc_pa_lock);
	173	list_splice(&tmp_list, &xprt->bc_pa_list);
	174	xprt_inc_alloc_count(xprt, min_reqs);
	175	spin_unlock_bh(&xprt->bc_pa_lock);
	176
	177	dprintk("RPC: setup backchannel transport done\n");
	178	return 0;
	179
	180	out_free:
	181	/*
	182	* Memory allocation failed, free the temporary list
	183	*/
1dddda86 TM	184	while (!list_empty(&tmp_list)) {
	185	req = list_first_entry(&tmp_list,
	186	struct rpc_rqst,
	187	rq_bc_pa_list);
62835679	188	list_del(&req->rq_bc_pa_list);
fb7a0b9a	189	xprt_free_allocation(req);
62835679	190	}
fb7a0b9a RL	191
fb7a0b9a RL	192	dprintk("RPC: setup backchannel transport failed\n");
d24bab93	193	return -ENOMEM;
fb7a0b9a	194	}
0d961aa9	195	EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
fb7a0b9a	196
2c53040f BH	197	/**
	198	* xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
	199	* @xprt: the transport holding the preallocated strucures
	200	* @max_reqs the maximum number of preallocated structures to destroy
	201	*
fb7a0b9a RL	202	* Since these structures may have been allocated by multiple calls
	203	* to xprt_setup_backchannel, we only destroy up to the maximum number
	204	* of reqs specified by the caller.
fb7a0b9a RL	205	*/
	206	void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
	207	{
	208	struct rpc_rqst req = NULL, tmp = NULL;
	209
	210	dprintk("RPC: destroy backchannel transport\n");
	211
c4ded8d9 WAA	212	if (max_reqs == 0)
	213	goto out;
	214
fb7a0b9a RL	215	spin_lock_bh(&xprt->bc_pa_lock);
	216	xprt_dec_alloc_count(xprt, max_reqs);
	217	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
	218	dprintk("RPC: req=%p\n", req);
62835679	219	list_del(&req->rq_bc_pa_list);
fb7a0b9a RL	220	xprt_free_allocation(req);
	221	if (--max_reqs == 0)
	222	break;
	223	}
	224	spin_unlock_bh(&xprt->bc_pa_lock);
	225
c4ded8d9	226	out:
fb7a0b9a RL	227	dprintk("RPC: backchannel list empty= %s\n",
	228	list_empty(&xprt->bc_pa_list) ? "true" : "false");
	229	}
0d961aa9	230	EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
fb7a0b9a	231
2ea24497	232	static struct rpc_rqst xprt_alloc_bc_request(struct rpc_xprt xprt, __be32 xid)
fb7a0b9a	233	{
2ea24497	234	struct rpc_rqst *req = NULL;
fb7a0b9a RL	235
fb7a0b9a RL	236	dprintk("RPC: allocate a backchannel request\n");
0d2a970d	237	if (atomic_read(&xprt->bc_free_slots) <= 0)
2ea24497	238	goto not_found;
0d2a970d TM	239	if (list_empty(&xprt->bc_pa_list)) {
	240	req = xprt_alloc_bc_req(xprt, GFP_ATOMIC);
	241	if (!req)
	242	goto not_found;
	243	/* Note: this 'free' request adds it to xprt->bc_pa_list */
	244	xprt_free_bc_request(req);
	245	}
2ea24497 TM	246	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
	247	rq_bc_pa_list);
	248	req->rq_reply_bytes_recvd = 0;
	249	req->rq_bytes_sent = 0;
	250	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
fb7a0b9a	251	sizeof(req->rq_private_buf));
2ea24497 TM	252	req->rq_xid = xid;
	253	req->rq_connect_cookie = xprt->connect_cookie;
	254	not_found:
fb7a0b9a RL	255	dprintk("RPC: backchannel req=%p\n", req);
	256	return req;
	257	}
	258
	259	/*
	260	* Return the preallocated rpc_rqst structure and XDR buffers
	261	* associated with this rpc_task.
	262	*/
	263	void xprt_free_bc_request(struct rpc_rqst *req)
	264	{
	265	struct rpc_xprt *xprt = req->rq_xprt;
	266
	267	dprintk("RPC: free backchannel req=%p\n", req);
	268
2ea24497	269	req->rq_connect_cookie = xprt->connect_cookie - 1;
4e857c58	270	smp_mb__before_atomic();
fb7a0b9a	271	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
4e857c58	272	smp_mb__after_atomic();
fb7a0b9a	273
0d2a970d TM	274	/*
	275	* Return it to the list of preallocations so that it
	276	* may be reused by a new callback request.
	277	*/
	278	spin_lock_bh(&xprt->bc_pa_lock);
	279	if (xprt_need_to_requeue(xprt)) {
	280	list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
	281	xprt->bc_alloc_count++;
	282	req = NULL;
	283	}
	284	spin_unlock_bh(&xprt->bc_pa_lock);
	285	if (req != NULL) {
fb7a0b9a RL	286	/*
	287	* The last remaining session was destroyed while this
	288	* entry was in use. Free the entry and don't attempt
	289	* to add back to the list because there is no need to
	290	* have anymore preallocated entries.
	291	*/
	292	dprintk("RPC: Last session removed req=%p\n", req);
	293	xprt_free_allocation(req);
	294	return;
	295	}
fb7a0b9a RL	296	}
fb7a0b9a RL	297
2ea24497 TM	298	/*
	299	* One or more rpc_rqst structure have been preallocated during the
	300	* backchannel setup. Buffer space for the send and private XDR buffers
	301	* has been preallocated as well. Use xprt_alloc_bc_request to allocate
	302	* to this request. Use xprt_free_bc_request to return it.
	303	*
	304	* We know that we're called in soft interrupt context, grab the spin_lock
	305	* since there is no need to grab the bottom half spin_lock.
	306	*
	307	* Return an available rpc_rqst, otherwise NULL if non are available.
	308	*/
	309	struct rpc_rqst xprt_lookup_bc_request(struct rpc_xprt xprt, __be32 xid)
	310	{
	311	struct rpc_rqst *req;
	312
	313	spin_lock(&xprt->bc_pa_lock);
	314	list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
	315	if (req->rq_connect_cookie != xprt->connect_cookie)
	316	continue;
	317	if (req->rq_xid == xid)
	318	goto found;
	319	}
	320	req = xprt_alloc_bc_request(xprt, xid);
	321	found:
	322	spin_unlock(&xprt->bc_pa_lock);
	323	return req;
	324	}
	325
	326	/*
	327	* Add callback request to callback list. The callback
	328	* service sleeps on the sv_cb_waitq waiting for new
	329	* requests. Wake it up after adding enqueing the
	330	* request.
	331	*/
	332	void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
	333	{
	334	struct rpc_xprt *xprt = req->rq_xprt;
	335	struct svc_serv *bc_serv = xprt->bc_serv;
	336
813b00d6 CL	337	spin_lock(&xprt->bc_pa_lock);
813b00d6 CL	338	list_del(&req->rq_bc_pa_list);
0d2a970d	339	xprt->bc_alloc_count--;
813b00d6 CL	340	spin_unlock(&xprt->bc_pa_lock);
813b00d6 CL	341
2ea24497 TM	342	req->rq_private_buf.len = copied;
	343	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	344
	345	dprintk("RPC: add callback request to list\n");
	346	spin_lock(&bc_serv->sv_cb_lock);
2ea24497 TM	347	list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
	348	wake_up(&bc_serv->sv_cb_waitq);
	349	spin_unlock(&bc_serv->sv_cb_lock);
	350	}
	351