SUNRPC: Make num_reqs a non-atomic integer

If recording xprt->stat.max_slots is moved into xprt_alloc_slot,
then xprt->num_reqs is never manipulated outside
xprt->reserve_lock. There's no longer a need for xprt->num_reqs to
be atomic.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index ad322cec049abd202878d3da0f6c71463d453e37..5fea0fb420df2d3a42037e7e420aea1f38e05bd8 100644 (file)
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -197,7 +197,7 @@ struct rpc_xprt {
        struct list_head        free;           /* free slots */
        unsigned int            max_reqs;       /* max number of slots */
        unsigned int            min_reqs;       /* min number of slots */
-       atomic_t                num_reqs;       /* total slots */
+       unsigned int            num_reqs;       /* total slots */
        unsigned long           state;          /* transport state */
        unsigned char           resvport   : 1; /* use a reserved port */
        atomic_t                swapper;        /* we're swapping over this

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 73f05a1fbc197c48c6df85f6dce503d14cac4e34..70f005044f06417ee09c94b85b9d125dc34da206 100644 (file)
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1009,7 +1009,7 @@ void xprt_transmit(struct rpc_task *task)
        struct rpc_rqst *req = task->tk_rqstp;
        struct rpc_xprt *xprt = req->rq_xprt;
        unsigned int connect_cookie;
-       int status, numreqs;
+       int status;
 
        dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 
@@ -1047,9 +1047,6 @@ void xprt_transmit(struct rpc_task *task)
 
        xprt->ops->set_retrans_timeout(task);
 
-       numreqs = atomic_read(&xprt->num_reqs);
-       if (numreqs > xprt->stat.max_slots)
-               xprt->stat.max_slots = numreqs;
        xprt->stat.sends++;
        xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
        xprt->stat.bklog_u += xprt->backlog.qlen;
@@ -1111,14 +1108,15 @@ static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
 {
        struct rpc_rqst *req = ERR_PTR(-EAGAIN);
 
-       if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
+       if (xprt->num_reqs >= xprt->max_reqs)
                goto out;
+       ++xprt->num_reqs;
        spin_unlock(&xprt->reserve_lock);
        req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
        spin_lock(&xprt->reserve_lock);
        if (req != NULL)
                goto out;
-       atomic_dec(&xprt->num_reqs);
+       --xprt->num_reqs;
        req = ERR_PTR(-ENOMEM);
 out:
        return req;
@@ -1126,7 +1124,8 @@ out:
 
 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 {
-       if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
+       if (xprt->num_reqs > xprt->min_reqs) {
+               --xprt->num_reqs;
                kfree(req);
                return true;
        }
@@ -1162,6 +1161,8 @@ void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
        spin_unlock(&xprt->reserve_lock);
        return;
 out_init_req:
+       xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
+                                    xprt->num_reqs);
        task->tk_status = 0;
        task->tk_rqstp = req;
        xprt_request_init(task, xprt);
@@ -1229,7 +1230,7 @@ struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
        else
                xprt->max_reqs = num_prealloc;
        xprt->min_reqs = num_prealloc;
-       atomic_set(&xprt->num_reqs, num_prealloc);
+       xprt->num_reqs = num_prealloc;
 
        return xprt;