[PATCH 1/2] svcrpc: make svc_age_temp_xprts enqueue under sv_lock

From: J. Bruce Fields
Date: Fri Feb 15 2013 - 14:23:14 EST

svc_age_temp_xprts expires xprts in a two-step process: first it takes
the sv_lock and moves the xprts to expire off their server-wide list
(sv_tempsocks or sv_permsocks) to a local list. Then it drops the
sv_lock and enqueues and puts each one.

I see no reason for this: svc_xprt_enqueue() will take sp_lock, but the
sv_lock and sp_lock are not otherwise nested anywhere (and documentation
at the top of this file claims it's correct to nest these with sp_lock

Cc: stable@xxxxxxxxxx
Tested-by: Jason Tibbitts <tibbs@xxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
net/sunrpc/svc_xprt.c | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 5a9d40c..11a33c8 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -863,7 +863,6 @@ static void svc_age_temp_xprts(unsigned long closure)
struct svc_serv *serv = (struct svc_serv *)closure;
struct svc_xprt *xprt;
struct list_head *le, *next;
- LIST_HEAD(to_be_aged);


@@ -884,25 +883,15 @@ static void svc_age_temp_xprts(unsigned long closure)
if (atomic_read(&xprt->xpt_ref.refcount) > 1 ||
test_bit(XPT_BUSY, &xprt->xpt_flags))
- svc_xprt_get(xprt);
- list_move(le, &to_be_aged);
+ list_del_init(le);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
set_bit(XPT_DETACHED, &xprt->xpt_flags);
- }
- spin_unlock_bh(&serv->sv_lock);
- while (!list_empty(&to_be_aged)) {
- le = to_be_aged.next;
- /* fiddling the xpt_list node is safe 'cos we're XPT_DETACHED */
- list_del_init(le);
- xprt = list_entry(le, struct svc_xprt, xpt_list);
dprintk("queuing xprt %p for closing\n", xprt);

/* a thread will dequeue and close it soon */
- svc_xprt_put(xprt);
+ spin_unlock_bh(&serv->sv_lock);

mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);

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