@@ -23,6 +23,7 @@ static int svc_deferred_recv(struct svc_rqst *rqstp);
static struct cache_deferred_req *svc_defer(struct cache_req *req);
static void svc_age_temp_xprts(unsigned long closure);
static void svc_delete_xprt(struct svc_xprt *xprt);
+static void svc_xprt_do_enqueue(struct svc_xprt *xprt);
/* apparently the "standard" is that clients close
* idle connections after 5 minutes, servers after
@@ -222,11 +223,12 @@ static void svc_xprt_received(struct svc_xprt *xprt)
if (!test_bit(XPT_BUSY, &xprt->xpt_flags))
return;
/* As soon as we clear busy, the xprt could be closed and
- * 'put', so we need a reference to call svc_xprt_enqueue with:
+ * 'put', so we need a reference to call svc_xprt_do_enqueue with:
*/
svc_xprt_get(xprt);
+ smp_mb__before_clear_bit();
clear_bit(XPT_BUSY, &xprt->xpt_flags);
- svc_xprt_enqueue(xprt);
+ svc_xprt_do_enqueue(xprt);
svc_xprt_put(xprt);
}
@@ -335,12 +337,7 @@ static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
return false;
}
-/*
- * Queue up a transport with data pending. If there are idle nfsd
- * processes, wake 'em up.
- *
- */
-void svc_xprt_enqueue(struct svc_xprt *xprt)
+static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
{
struct svc_pool *pool;
struct svc_rqst *rqstp;
@@ -398,6 +395,18 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
out_unlock:
spin_unlock_bh(&pool->sp_lock);
}
+
+/*
+ * Queue up a transport with data pending. If there are idle nfsd
+ * processes, wake 'em up.
+ *
+ */
+void svc_xprt_enqueue(struct svc_xprt *xprt)
+{
+ if (test_bit(XPT_BUSY, &xprt->xpt_flags))
+ return;
+ svc_xprt_do_enqueue(xprt);
+}
EXPORT_SYMBOL_GPL(svc_xprt_enqueue);
/*
Ensure that all calls to svc_xprt_enqueue() except svc_xprt_received() check the value of XPT_BUSY, before attempting to grab spinlocks etc. This is to avoid situations such as the following "perf" trace, which shows heavy contention on the pool spinlock: 54.15% nfsd [kernel.kallsyms] [k] _raw_spin_lock_bh | --- _raw_spin_lock_bh | |--71.43%-- svc_xprt_enqueue | | | |--50.31%-- svc_reserve | | | |--31.35%-- svc_xprt_received | | | |--18.34%-- svc_tcp_data_ready ... Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> --- net/sunrpc/svc_xprt.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)