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Subject[ 064/153] svcrpc: make svc_age_temp_xprts enqueue under sv_lock
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "J. Bruce Fields" <bfields@redhat.com>

commit e75bafbff2270993926abcc31358361db74a9bc2 upstream.

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
inside.)

Tested-by: Jason Tibbitts <tibbs@math.uh.edu>
Tested-by: Paweł Sikora <pawel.sikora@agmk.net>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/sunrpc/svc_xprt.c | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)

--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -816,7 +816,6 @@ static void svc_age_temp_xprts(unsigned
struct svc_serv *serv = (struct svc_serv *)closure;
struct svc_xprt *xprt;
struct list_head *le, *next;
- LIST_HEAD(to_be_aged);

dprintk("svc_age_temp_xprts\n");

@@ -837,25 +836,15 @@ static void svc_age_temp_xprts(unsigned
if (atomic_read(&xprt->xpt_ref.refcount) > 1 ||
test_bit(XPT_BUSY, &xprt->xpt_flags))
continue;
- 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_enqueue(xprt);
- 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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