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SUNRPC: Make slot allocation more reliable

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In xprt_alloc_slot(), the spin lock is only needed to provide atomicity
between the atomic_add_unless() failure and the call to xprt_add_backlog().
We do not actually need to hold it across the memory allocation itself.

By dropping the lock, we can use a more resilient GFP_NOFS allocation,
just as we now do in the rest of the RPC client code.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Trond Myklebust 2017-06-20 19:35:39 -04:00 committed by Anna Schumaker
parent 818a8dbe83
commit 92ea011f7c
1 changed files with 5 additions and 3 deletions
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8
net/sunrpc/xprt.c
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@ -1047,13 +1047,15 @@ out:
return ret; return ret;
} }
static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags) static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
{ {
struct rpc_rqst *req = ERR_PTR(-EAGAIN); struct rpc_rqst *req = ERR_PTR(-EAGAIN);
if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs)) if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
goto out; goto out;
req = kzalloc(sizeof(struct rpc_rqst), gfp_flags); spin_unlock(&xprt->reserve_lock);
req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
spin_lock(&xprt->reserve_lock);
if (req != NULL) if (req != NULL)
goto out; goto out;
atomic_dec(&xprt->num_reqs); atomic_dec(&xprt->num_reqs);
@ -1081,7 +1083,7 @@ void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
list_del(&req->rq_list); list_del(&req->rq_list);
goto out_init_req; goto out_init_req;
} }
req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN); req = xprt_dynamic_alloc_slot(xprt);
if (!IS_ERR(req)) if (!IS_ERR(req))
goto out_init_req; goto out_init_req;
switch (PTR_ERR(req)) { switch (PTR_ERR(req)) {