[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)
{
	if (!xprt->ops->bc_setup)
		return 0;
	return xprt->ops->bc_setup(xprt, min_reqs);
}
EXPORT_SYMBOL_GPL(xprt_setup_backchannel);

int xprt_setup_bc(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;
}

/**
 * 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)
{
	if (xprt->ops->bc_destroy)
		xprt->ops->bc_destroy(xprt, max_reqs);
}
EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);

void xprt_destroy_bc(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");
}

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;
		list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
		xprt->bc_alloc_count++;
	}
	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;

	xprt->ops->bc_free_rqst(req);
}

void xprt_free_bc_rqst(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_dec_alloc_count(xprt, 1);
	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)
42e5c3e2 CL	140	{
	141	if (!xprt->ops->bc_setup)
	142	return 0;
	143	return xprt->ops->bc_setup(xprt, min_reqs);
	144	}
	145	EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
	146
	147	int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs)
fb7a0b9a	148	{
1dddda86	149	struct rpc_rqst *req;
fb7a0b9a RL	150	struct list_head tmp_list;
	151	int i;
	152
	153	dprintk("RPC: setup backchannel transport\n");
	154
	155	/*
	156	* We use a temporary list to keep track of the preallocated
	157	* buffers. Once we're done building the list we splice it
	158	* into the backchannel preallocation list off of the rpc_xprt
	159	* struct. This helps minimize the amount of time the list
	160	* lock is held on the rpc_xprt struct. It also makes cleanup
	161	* easier in case of memory allocation errors.
	162	*/
	163	INIT_LIST_HEAD(&tmp_list);
	164	for (i = 0; i < min_reqs; i++) {
	165	/* Pre-allocate one backchannel rpc_rqst */
1dddda86	166	req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
fb7a0b9a RL	167	if (req == NULL) {
	168	printk(KERN_ERR "Failed to create bc rpc_rqst\n");
	169	goto out_free;
	170	}
	171
	172	/* Add the allocated buffer to the tmp list */
	173	dprintk("RPC: adding req= %p\n", req);
	174	list_add(&req->rq_bc_pa_list, &tmp_list);
fb7a0b9a RL	175	}
	176
	177	/*
	178	* Add the temporary list to the backchannel preallocation list
	179	*/
	180	spin_lock_bh(&xprt->bc_pa_lock);
	181	list_splice(&tmp_list, &xprt->bc_pa_list);
	182	xprt_inc_alloc_count(xprt, min_reqs);
	183	spin_unlock_bh(&xprt->bc_pa_lock);
	184
	185	dprintk("RPC: setup backchannel transport done\n");
	186	return 0;
	187
	188	out_free:
	189	/*
	190	* Memory allocation failed, free the temporary list
	191	*/
1dddda86 TM	192	while (!list_empty(&tmp_list)) {
	193	req = list_first_entry(&tmp_list,
	194	struct rpc_rqst,
	195	rq_bc_pa_list);
62835679	196	list_del(&req->rq_bc_pa_list);
fb7a0b9a	197	xprt_free_allocation(req);
62835679	198	}
fb7a0b9a RL	199
fb7a0b9a RL	200	dprintk("RPC: setup backchannel transport failed\n");
d24bab93	201	return -ENOMEM;
fb7a0b9a	202	}
fb7a0b9a	203
2c53040f BH	204	/**
	205	* xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
	206	* @xprt: the transport holding the preallocated strucures
	207	* @max_reqs the maximum number of preallocated structures to destroy
	208	*
fb7a0b9a RL	209	* Since these structures may have been allocated by multiple calls
	210	* to xprt_setup_backchannel, we only destroy up to the maximum number
	211	* of reqs specified by the caller.
fb7a0b9a RL	212	*/
fb7a0b9a RL	213	void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
42e5c3e2 CL	214	{
	215	if (xprt->ops->bc_destroy)
	216	xprt->ops->bc_destroy(xprt, max_reqs);
	217	}
	218	EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
	219
	220	void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs)
fb7a0b9a RL	221	{
	222	struct rpc_rqst req = NULL, tmp = NULL;
	223
	224	dprintk("RPC: destroy backchannel transport\n");
	225
c4ded8d9 WAA	226	if (max_reqs == 0)
	227	goto out;
	228
fb7a0b9a RL	229	spin_lock_bh(&xprt->bc_pa_lock);
	230	xprt_dec_alloc_count(xprt, max_reqs);
	231	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
	232	dprintk("RPC: req=%p\n", req);
62835679	233	list_del(&req->rq_bc_pa_list);
fb7a0b9a RL	234	xprt_free_allocation(req);
	235	if (--max_reqs == 0)
	236	break;
	237	}
	238	spin_unlock_bh(&xprt->bc_pa_lock);
	239
c4ded8d9	240	out:
fb7a0b9a RL	241	dprintk("RPC: backchannel list empty= %s\n",
	242	list_empty(&xprt->bc_pa_list) ? "true" : "false");
	243	}
fb7a0b9a	244
2ea24497	245	static struct rpc_rqst xprt_alloc_bc_request(struct rpc_xprt xprt, __be32 xid)
fb7a0b9a	246	{
2ea24497	247	struct rpc_rqst *req = NULL;
fb7a0b9a RL	248
fb7a0b9a RL	249	dprintk("RPC: allocate a backchannel request\n");
0d2a970d	250	if (atomic_read(&xprt->bc_free_slots) <= 0)
2ea24497	251	goto not_found;
0d2a970d TM	252	if (list_empty(&xprt->bc_pa_list)) {
	253	req = xprt_alloc_bc_req(xprt, GFP_ATOMIC);
	254	if (!req)
	255	goto not_found;
68514471 TM	256	list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
68514471 TM	257	xprt->bc_alloc_count++;
0d2a970d	258	}
2ea24497 TM	259	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
	260	rq_bc_pa_list);
	261	req->rq_reply_bytes_recvd = 0;
	262	req->rq_bytes_sent = 0;
	263	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
fb7a0b9a	264	sizeof(req->rq_private_buf));
2ea24497 TM	265	req->rq_xid = xid;
	266	req->rq_connect_cookie = xprt->connect_cookie;
	267	not_found:
fb7a0b9a RL	268	dprintk("RPC: backchannel req=%p\n", req);
	269	return req;
	270	}
	271
	272	/*
	273	* Return the preallocated rpc_rqst structure and XDR buffers
	274	* associated with this rpc_task.
	275	*/
	276	void xprt_free_bc_request(struct rpc_rqst *req)
	277	{
	278	struct rpc_xprt *xprt = req->rq_xprt;
	279
42e5c3e2 CL	280	xprt->ops->bc_free_rqst(req);
	281	}
	282
	283	void xprt_free_bc_rqst(struct rpc_rqst *req)
	284	{
	285	struct rpc_xprt *xprt = req->rq_xprt;
	286
fb7a0b9a RL	287	dprintk("RPC: free backchannel req=%p\n", req);
fb7a0b9a RL	288
2ea24497	289	req->rq_connect_cookie = xprt->connect_cookie - 1;
4e857c58	290	smp_mb__before_atomic();
fb7a0b9a	291	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
4e857c58	292	smp_mb__after_atomic();
fb7a0b9a	293
0d2a970d TM	294	/*
	295	* Return it to the list of preallocations so that it
	296	* may be reused by a new callback request.
	297	*/
	298	spin_lock_bh(&xprt->bc_pa_lock);
	299	if (xprt_need_to_requeue(xprt)) {
	300	list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
	301	xprt->bc_alloc_count++;
	302	req = NULL;
	303	}
	304	spin_unlock_bh(&xprt->bc_pa_lock);
	305	if (req != NULL) {
fb7a0b9a RL	306	/*
	307	* The last remaining session was destroyed while this
	308	* entry was in use. Free the entry and don't attempt
	309	* to add back to the list because there is no need to
	310	* have anymore preallocated entries.
	311	*/
	312	dprintk("RPC: Last session removed req=%p\n", req);
	313	xprt_free_allocation(req);
	314	return;
	315	}
fb7a0b9a RL	316	}
fb7a0b9a RL	317
2ea24497 TM	318	/*
	319	* One or more rpc_rqst structure have been preallocated during the
	320	* backchannel setup. Buffer space for the send and private XDR buffers
	321	* has been preallocated as well. Use xprt_alloc_bc_request to allocate
	322	* to this request. Use xprt_free_bc_request to return it.
	323	*
	324	* We know that we're called in soft interrupt context, grab the spin_lock
	325	* since there is no need to grab the bottom half spin_lock.
	326	*
	327	* Return an available rpc_rqst, otherwise NULL if non are available.
	328	*/
	329	struct rpc_rqst xprt_lookup_bc_request(struct rpc_xprt xprt, __be32 xid)
	330	{
	331	struct rpc_rqst *req;
	332
	333	spin_lock(&xprt->bc_pa_lock);
	334	list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
	335	if (req->rq_connect_cookie != xprt->connect_cookie)
	336	continue;
	337	if (req->rq_xid == xid)
	338	goto found;
	339	}
	340	req = xprt_alloc_bc_request(xprt, xid);
	341	found:
	342	spin_unlock(&xprt->bc_pa_lock);
	343	return req;
	344	}
	345
	346	/*
	347	* Add callback request to callback list. The callback
	348	* service sleeps on the sv_cb_waitq waiting for new
	349	* requests. Wake it up after adding enqueing the
	350	* request.
	351	*/
	352	void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
	353	{
	354	struct rpc_xprt *xprt = req->rq_xprt;
	355	struct svc_serv *bc_serv = xprt->bc_serv;
	356
813b00d6 CL	357	spin_lock(&xprt->bc_pa_lock);
813b00d6 CL	358	list_del(&req->rq_bc_pa_list);
1980bd4d	359	xprt_dec_alloc_count(xprt, 1);
813b00d6 CL	360	spin_unlock(&xprt->bc_pa_lock);
813b00d6 CL	361
2ea24497 TM	362	req->rq_private_buf.len = copied;
	363	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	364
	365	dprintk("RPC: add callback request to list\n");
	366	spin_lock(&bc_serv->sv_cb_lock);
2ea24497 TM	367	list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
	368	wake_up(&bc_serv->sv_cb_waitq);
	369	spin_unlock(&bc_serv->sv_cb_lock);
	370	}
	371