5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chuck Lever <chuck.lever@xxxxxxxxxx>
[ Upstream commit c0219c499799c1e92bd570c15a47e6257a27bb15 ]
Neil says:
"These functions were separated in commit 0971374e2818 ("SUNRPC:
Reduce contention in svc_xprt_enqueue()") so that the XPT_BUSY check
happened before taking any spinlocks.
We have since moved or removed the spinlocks so the extra test is
fairly pointless."
I've made this a separate patch in case the XPT_BUSY change has
unexpected consequences and needs to be reverted.
Suggested-by: Neil Brown <neilb@xxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/sunrpc/svc_xprt.c | 26 ++++++++++----------------
1 file changed, 10 insertions(+), 16 deletions(-)
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 833952db23192..b5e80817b02f5 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -31,7 +31,6 @@ 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(struct timer_list *t);
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
@@ -254,12 +253,12 @@ void svc_xprt_received(struct svc_xprt *xprt)
trace_svc_xprt_received(xprt);
/* As soon as we clear busy, the xprt could be closed and
- * 'put', so we need a reference to call svc_xprt_do_enqueue with:
+ * 'put', so we need a reference to call svc_xprt_enqueue with:
*/
svc_xprt_get(xprt);
smp_mb__before_atomic();
clear_bit(XPT_BUSY, &xprt->xpt_flags);
- svc_xprt_do_enqueue(xprt);
+ svc_xprt_enqueue(xprt);
svc_xprt_put(xprt);
}
EXPORT_SYMBOL_GPL(svc_xprt_received);
@@ -399,6 +398,8 @@ static bool svc_xprt_ready(struct svc_xprt *xprt)
smp_rmb();
xpt_flags = READ_ONCE(xprt->xpt_flags);
+ if (xpt_flags & BIT(XPT_BUSY))
+ return false;
if (xpt_flags & (BIT(XPT_CONN) | BIT(XPT_CLOSE)))
return true;
if (xpt_flags & (BIT(XPT_DATA) | BIT(XPT_DEFERRED))) {
@@ -411,7 +412,12 @@ static bool svc_xprt_ready(struct svc_xprt *xprt)
return false;
}
-static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
+/**
+ * svc_xprt_enqueue - Queue a transport on an idle nfsd thread
+ * @xprt: transport with data pending
+ *
+ */
+void svc_xprt_enqueue(struct svc_xprt *xprt)
{
struct svc_pool *pool;
struct svc_rqst *rqstp = NULL;
@@ -455,18 +461,6 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
put_cpu();
trace_svc_xprt_do_enqueue(xprt, rqstp);
}
-
-/*
- * 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);
/*
--
2.43.0
