[mirror_ubuntu-bionic-kernel.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;
	xdr_buf_init(buf, page_address(page), 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(&xprt->bc_pa_lock);
	list_splice(&tmp_list, &xprt->bc_pa_list);
	xprt_inc_alloc_count(xprt, min_reqs);
	spin_unlock(&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;
b9c5bc03	79	xdr_buf_init(buf, page_address(page), PAGE_SIZE);
1dddda86 TM	80	return 0;
	81	}
	82
	83	static
	84	struct rpc_rqst xprt_alloc_bc_req(struct rpc_xprt xprt, gfp_t gfp_flags)
	85	{
	86	struct rpc_rqst *req;
	87
	88	/* Pre-allocate one backchannel rpc_rqst */
	89	req = kzalloc(sizeof(*req), gfp_flags);
	90	if (req == NULL)
	91	return NULL;
	92
	93	req->rq_xprt = xprt;
	94	INIT_LIST_HEAD(&req->rq_list);
	95	INIT_LIST_HEAD(&req->rq_bc_list);
	96
	97	/* Preallocate one XDR receive buffer */
	98	if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
	99	printk(KERN_ERR "Failed to create bc receive xbuf\n");
	100	goto out_free;
	101	}
	102	req->rq_rcv_buf.len = PAGE_SIZE;
	103
	104	/* Preallocate one XDR send buffer */
	105	if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
	106	printk(KERN_ERR "Failed to create bc snd xbuf\n");
	107	goto out_free;
	108	}
	109	return req;
	110	out_free:
	111	xprt_free_allocation(req);
	112	return NULL;
	113	}
	114
fb7a0b9a RL	115	/*
	116	* Preallocate up to min_reqs structures and related buffers for use
	117	* by the backchannel. This function can be called multiple times
	118	* when creating new sessions that use the same rpc_xprt. The
	119	* preallocated buffers are added to the pool of resources used by
	120	* the rpc_xprt. Anyone of these resources may be used used by an
	121	* incoming callback request. It's up to the higher levels in the
	122	* stack to enforce that the maximum number of session slots is not
	123	* being exceeded.
	124	*
	125	* Some callback arguments can be large. For example, a pNFS server
	126	* using multiple deviceids. The list can be unbound, but the client
	127	* has the ability to tell the server the maximum size of the callback
	128	* requests. Each deviceID is 16 bytes, so allocate one page
	129	* for the arguments to have enough room to receive a number of these
	130	* deviceIDs. The NFS client indicates to the pNFS server that its
	131	* callback requests can be up to 4096 bytes in size.
	132	*/
	133	int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
42e5c3e2 CL	134	{
	135	if (!xprt->ops->bc_setup)
	136	return 0;
	137	return xprt->ops->bc_setup(xprt, min_reqs);
	138	}
	139	EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
	140
	141	int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs)
fb7a0b9a	142	{
1dddda86	143	struct rpc_rqst *req;
fb7a0b9a RL	144	struct list_head tmp_list;
	145	int i;
	146
	147	dprintk("RPC: setup backchannel transport\n");
	148
	149	/*
	150	* We use a temporary list to keep track of the preallocated
	151	* buffers. Once we're done building the list we splice it
	152	* into the backchannel preallocation list off of the rpc_xprt
	153	* struct. This helps minimize the amount of time the list
	154	* lock is held on the rpc_xprt struct. It also makes cleanup
	155	* easier in case of memory allocation errors.
	156	*/
	157	INIT_LIST_HEAD(&tmp_list);
	158	for (i = 0; i < min_reqs; i++) {
	159	/* Pre-allocate one backchannel rpc_rqst */
1dddda86	160	req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
fb7a0b9a RL	161	if (req == NULL) {
	162	printk(KERN_ERR "Failed to create bc rpc_rqst\n");
	163	goto out_free;
	164	}
	165
	166	/* Add the allocated buffer to the tmp list */
	167	dprintk("RPC: adding req= %p\n", req);
	168	list_add(&req->rq_bc_pa_list, &tmp_list);
fb7a0b9a RL	169	}
	170
	171	/*
	172	* Add the temporary list to the backchannel preallocation list
	173	*/
c89091c8	174	spin_lock(&xprt->bc_pa_lock);
fb7a0b9a RL	175	list_splice(&tmp_list, &xprt->bc_pa_list);
fb7a0b9a RL	176	xprt_inc_alloc_count(xprt, min_reqs);
c89091c8	177	spin_unlock(&xprt->bc_pa_lock);
fb7a0b9a RL	178
	179	dprintk("RPC: setup backchannel transport done\n");
	180	return 0;
	181
	182	out_free:
	183	/*
	184	* Memory allocation failed, free the temporary list
	185	*/
1dddda86 TM	186	while (!list_empty(&tmp_list)) {
	187	req = list_first_entry(&tmp_list,
	188	struct rpc_rqst,
	189	rq_bc_pa_list);
62835679	190	list_del(&req->rq_bc_pa_list);
fb7a0b9a	191	xprt_free_allocation(req);
62835679	192	}
fb7a0b9a RL	193
fb7a0b9a RL	194	dprintk("RPC: setup backchannel transport failed\n");
d24bab93	195	return -ENOMEM;
fb7a0b9a	196	}
fb7a0b9a	197
2c53040f BH	198	/**
	199	* xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
	200	* @xprt: the transport holding the preallocated strucures
	201	* @max_reqs the maximum number of preallocated structures to destroy
	202	*
fb7a0b9a RL	203	* Since these structures may have been allocated by multiple calls
	204	* to xprt_setup_backchannel, we only destroy up to the maximum number
	205	* of reqs specified by the caller.
fb7a0b9a RL	206	*/
fb7a0b9a RL	207	void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
42e5c3e2 CL	208	{
	209	if (xprt->ops->bc_destroy)
	210	xprt->ops->bc_destroy(xprt, max_reqs);
	211	}
	212	EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
	213
	214	void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs)
fb7a0b9a RL	215	{
	216	struct rpc_rqst req = NULL, tmp = NULL;
	217
	218	dprintk("RPC: destroy backchannel transport\n");
	219
c4ded8d9 WAA	220	if (max_reqs == 0)
	221	goto out;
	222
fb7a0b9a RL	223	spin_lock_bh(&xprt->bc_pa_lock);
	224	xprt_dec_alloc_count(xprt, max_reqs);
	225	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
	226	dprintk("RPC: req=%p\n", req);
62835679	227	list_del(&req->rq_bc_pa_list);
fb7a0b9a RL	228	xprt_free_allocation(req);
	229	if (--max_reqs == 0)
	230	break;
	231	}
	232	spin_unlock_bh(&xprt->bc_pa_lock);
	233
c4ded8d9	234	out:
fb7a0b9a RL	235	dprintk("RPC: backchannel list empty= %s\n",
	236	list_empty(&xprt->bc_pa_list) ? "true" : "false");
	237	}
fb7a0b9a	238
2ea24497	239	static struct rpc_rqst xprt_alloc_bc_request(struct rpc_xprt xprt, __be32 xid)
fb7a0b9a	240	{
2ea24497	241	struct rpc_rqst *req = NULL;
fb7a0b9a RL	242
fb7a0b9a RL	243	dprintk("RPC: allocate a backchannel request\n");
0d2a970d	244	if (atomic_read(&xprt->bc_free_slots) <= 0)
2ea24497	245	goto not_found;
0d2a970d TM	246	if (list_empty(&xprt->bc_pa_list)) {
	247	req = xprt_alloc_bc_req(xprt, GFP_ATOMIC);
	248	if (!req)
	249	goto not_found;
68514471 TM	250	list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
68514471 TM	251	xprt->bc_alloc_count++;
0d2a970d	252	}
2ea24497 TM	253	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
	254	rq_bc_pa_list);
	255	req->rq_reply_bytes_recvd = 0;
	256	req->rq_bytes_sent = 0;
	257	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
fb7a0b9a	258	sizeof(req->rq_private_buf));
2ea24497 TM	259	req->rq_xid = xid;
	260	req->rq_connect_cookie = xprt->connect_cookie;
	261	not_found:
fb7a0b9a RL	262	dprintk("RPC: backchannel req=%p\n", req);
	263	return req;
	264	}
	265
	266	/*
	267	* Return the preallocated rpc_rqst structure and XDR buffers
	268	* associated with this rpc_task.
	269	*/
	270	void xprt_free_bc_request(struct rpc_rqst *req)
	271	{
	272	struct rpc_xprt *xprt = req->rq_xprt;
	273
42e5c3e2 CL	274	xprt->ops->bc_free_rqst(req);
	275	}
	276
	277	void xprt_free_bc_rqst(struct rpc_rqst *req)
	278	{
	279	struct rpc_xprt *xprt = req->rq_xprt;
	280
fb7a0b9a RL	281	dprintk("RPC: free backchannel req=%p\n", req);
fb7a0b9a RL	282
2ea24497	283	req->rq_connect_cookie = xprt->connect_cookie - 1;
4e857c58	284	smp_mb__before_atomic();
fb7a0b9a	285	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
4e857c58	286	smp_mb__after_atomic();
fb7a0b9a	287
0d2a970d TM	288	/*
	289	* Return it to the list of preallocations so that it
	290	* may be reused by a new callback request.
	291	*/
	292	spin_lock_bh(&xprt->bc_pa_lock);
	293	if (xprt_need_to_requeue(xprt)) {
	294	list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
	295	xprt->bc_alloc_count++;
	296	req = NULL;
	297	}
	298	spin_unlock_bh(&xprt->bc_pa_lock);
	299	if (req != NULL) {
fb7a0b9a RL	300	/*
	301	* The last remaining session was destroyed while this
	302	* entry was in use. Free the entry and don't attempt
	303	* to add back to the list because there is no need to
	304	* have anymore preallocated entries.
	305	*/
	306	dprintk("RPC: Last session removed req=%p\n", req);
	307	xprt_free_allocation(req);
	308	return;
	309	}
fb7a0b9a RL	310	}
fb7a0b9a RL	311
2ea24497 TM	312	/*
	313	* One or more rpc_rqst structure have been preallocated during the
	314	* backchannel setup. Buffer space for the send and private XDR buffers
	315	* has been preallocated as well. Use xprt_alloc_bc_request to allocate
	316	* to this request. Use xprt_free_bc_request to return it.
	317	*
	318	* We know that we're called in soft interrupt context, grab the spin_lock
	319	* since there is no need to grab the bottom half spin_lock.
	320	*
	321	* Return an available rpc_rqst, otherwise NULL if non are available.
	322	*/
	323	struct rpc_rqst xprt_lookup_bc_request(struct rpc_xprt xprt, __be32 xid)
	324	{
	325	struct rpc_rqst *req;
	326
	327	spin_lock(&xprt->bc_pa_lock);
	328	list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
	329	if (req->rq_connect_cookie != xprt->connect_cookie)
	330	continue;
	331	if (req->rq_xid == xid)
	332	goto found;
	333	}
	334	req = xprt_alloc_bc_request(xprt, xid);
	335	found:
	336	spin_unlock(&xprt->bc_pa_lock);
	337	return req;
	338	}
	339
	340	/*
	341	* Add callback request to callback list. The callback
	342	* service sleeps on the sv_cb_waitq waiting for new
	343	* requests. Wake it up after adding enqueing the
	344	* request.
	345	*/
	346	void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
	347	{
	348	struct rpc_xprt *xprt = req->rq_xprt;
	349	struct svc_serv *bc_serv = xprt->bc_serv;
	350
813b00d6 CL	351	spin_lock(&xprt->bc_pa_lock);
813b00d6 CL	352	list_del(&req->rq_bc_pa_list);
1980bd4d	353	xprt_dec_alloc_count(xprt, 1);
813b00d6 CL	354	spin_unlock(&xprt->bc_pa_lock);
813b00d6 CL	355
2ea24497 TM	356	req->rq_private_buf.len = copied;
	357	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	358
	359	dprintk("RPC: add callback request to list\n");
	360	spin_lock(&bc_serv->sv_cb_lock);
2ea24497 TM	361	list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
	362	wake_up(&bc_serv->sv_cb_waitq);
	363	spin_unlock(&bc_serv->sv_cb_lock);
	364	}
	365