diff options
| author | J. Bruce Fields <bfields@redhat.com> | 2012-08-17 17:31:53 -0400 |
|---|---|---|
| committer | Paul Gortmaker <paul.gortmaker@windriver.com> | 2014-02-10 16:11:34 -0500 |
| commit | 2b718efa69f2431de9df4b35e725316fa25d5310 (patch) | |
| tree | 650e79af8b074e00fc73d5eb0681ccffb90c8b38 | |
| parent | c8af16321375a4d6b4bc2cf874292d5943586d91 (diff) | |
svcrpc: fix svc_xprt_enqueue/svc_recv busy-looping
commit d10f27a750312ed5638c876e4bd6aa83664cccd8 upstream.
The rpc server tries to ensure that there will be room to send a reply
before it receives a request.
It does this by tracking, in xpt_reserved, an upper bound on the total
size of the replies that is has already committed to for the socket.
Currently it is adding in the estimate for a new reply *before* it
checks whether there is space available. If it finds that there is not
space, it then subtracts the estimate back out.
This may lead the subsequent svc_xprt_enqueue to decide that there is
space after all.
The results is a svc_recv() that will repeatedly return -EAGAIN, causing
server threads to loop without doing any actual work.
Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
| -rw-r--r-- | net/sunrpc/svc_xprt.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 957a7e88e827..afa0bceb67ad 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -310,7 +310,6 @@ static void svc_thread_dequeue(struct svc_pool *pool, struct svc_rqst *rqstp) */ void svc_xprt_enqueue(struct svc_xprt *xprt) { - struct svc_serv *serv = xprt->xpt_server; struct svc_pool *pool; struct svc_rqst *rqstp; int cpu; @@ -384,8 +383,6 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) rqstp, rqstp->rq_xprt); rqstp->rq_xprt = xprt; svc_xprt_get(xprt); - rqstp->rq_reserved = serv->sv_max_mesg; - atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved); pool->sp_stats.threads_woken++; BUG_ON(xprt->xpt_pool != pool); wake_up(&rqstp->rq_wait); @@ -663,8 +660,6 @@ int svc_recv(struct svc_rqst *rqstp, long timeout) if (xprt) { rqstp->rq_xprt = xprt; svc_xprt_get(xprt); - rqstp->rq_reserved = serv->sv_max_mesg; - atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved); } else { /* No data pending. Go to sleep */ svc_thread_enqueue(pool, rqstp); @@ -754,6 +749,8 @@ int svc_recv(struct svc_rqst *rqstp, long timeout) } else len = xprt->xpt_ops->xpo_recvfrom(rqstp); dprintk("svc: got len=%d\n", len); + rqstp->rq_reserved = serv->sv_max_mesg; + atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved); } /* No data, incomplete (TCP) read, or accept() */ |