From: David Woodhouse <dwmw2@infradead.org>
To: Krzysztof Mazur <krzysiek@podlesie.net>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>,
davem@davemloft.net
Subject: [PATCH v3 8/7] pppoatm: fix missing wakeup in pppoatm_send()
Date: Wed, 07 Nov 2012 12:52:14 +0000 [thread overview]
Message-ID: <1352292734.7340.35.camel@shinybook.infradead.org> (raw)
In-Reply-To: <1352240222-363-1-git-send-email-krzysiek@podlesie.net>
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Now that we can return zero from pppoatm_send() for reasons *other* than
the queue being full, that means we can't depend on a subsequent call to
pppoatm_pop() waking the queue, and we might leave it stalled
indefinitely.
Fix this by immediately scheduling the wakeup tasklet. As documented
already elsewhere, the PPP channel's ->downl lock protects against the
wakeup happening too soon and effectively being missed.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
----
Untested.
With this sorted, Acked-By: David Woodhouse <David.Woodhouse@intel.com<
to the other seven. Thanks.
diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
index 7507c20..56ad541 100644
--- a/net/atm/pppoatm.c
+++ b/net/atm/pppoatm.c
@@ -283,11 +283,11 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
vcc = ATM_SKB(skb)->vcc;
bh_lock_sock(sk_atm(vcc));
if (sock_owned_by_user(sk_atm(vcc)))
- goto nospace;
+ goto nospace_sched_wakeup;
if (test_bit(ATM_VF_RELEASED, &vcc->flags)
- || test_bit(ATM_VF_CLOSE, &vcc->flags)
- || !test_bit(ATM_VF_READY, &vcc->flags))
- goto nospace;
+ || test_bit(ATM_VF_CLOSE, &vcc->flags)
+ || !test_bit(ATM_VF_READY, &vcc->flags))
+ goto nospace_sched_wakeup;
switch (pvcc->encaps) { /* LLC encapsulation needed */
case e_llc:
@@ -328,7 +328,17 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
? DROP_PACKET : 1;
bh_unlock_sock(sk_atm(vcc));
return ret;
-nospace:
+ nospace_sched_wakeup:
+ /* If we're returning zero for reasons *other* than the queue
+ * being full, then we need to ensure that a wakeup will
+ * happen and not just leave the channel stalled for ever.
+ * Just schedule the wakeup tasklet directly. As observed in
+ * pppoatm_pop(), it'll take the channel's ->downl lock which
+ * is also held by our caller, so it can't happen "too soon"
+ * and cause us to effectively miss a wakeup.
+ */
+ tasklet_schedule(&pvcc->wakeup_tasklet);
+ nospace:
bh_unlock_sock(sk_atm(vcc));
/*
* We don't have space to send this SKB now, but we might have
--
David Woodhouse Open Source Technology Centre
David.Woodhouse@intel.com Intel Corporation
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next prev parent reply other threads:[~2012-11-07 12:52 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-06 22:16 [PATCH v3 0/7] pppoatm: fix multiple issues with pppoatm driver Krzysztof Mazur
2012-11-06 22:16 ` [PATCH v3 1/7] atm: detach protocol before closing vcc Krzysztof Mazur
2012-11-06 22:16 ` [PATCH v3 2/7] atm: add owner of push() callback to atmvcc Krzysztof Mazur
2012-11-07 19:05 ` chas williams - CONTRACTOR
2012-11-06 22:16 ` [PATCH v3 3/7] pppoatm: allow assign only on a connected socket Krzysztof Mazur
2012-11-06 22:16 ` [PATCH v3 4/7] pppoatm: fix module_put() race Krzysztof Mazur
2012-11-06 22:17 ` [PATCH v3 5/7] pppoatm: take ATM socket lock in pppoatm_send() Krzysztof Mazur
2012-11-06 22:57 ` Woodhouse, David
2012-11-06 22:17 ` [PATCH v3 6/7] pppoatm: don't send frames on not-ready vcc Krzysztof Mazur
2012-11-06 22:17 ` [PATCH v3 7/7] pppoatm: do not inline pppoatm_may_send() Krzysztof Mazur
2012-11-07 12:52 ` David Woodhouse [this message]
2012-11-09 21:30 ` [PATCH v3 8/7] pppoatm: fix missing wakeup in pppoatm_send() David Miller
2012-11-10 7:36 ` David Woodhouse
2012-11-10 18:38 ` David Miller
2012-11-10 20:23 ` Krzysztof Mazur
2012-11-10 21:02 ` David Woodhouse
2012-11-10 22:33 ` Krzysztof Mazur
2012-11-11 7:28 ` David Woodhouse
2012-11-11 11:04 ` Krzysztof Mazur
2012-11-11 11:39 ` David Woodhouse
2012-11-11 13:50 ` Krzysztof Mazur
2012-11-11 15:26 ` David Woodhouse
2012-11-11 16:12 ` Krzysztof Mazur
2012-11-11 17:03 ` David Woodhouse
2012-11-11 18:49 ` Krzysztof Mazur
2012-11-11 20:51 ` David Woodhouse
2012-11-11 22:57 ` Chas Williams (CONTRACTOR)
2012-11-27 13:27 ` David Woodhouse
2012-11-27 15:23 ` chas williams - CONTRACTOR
2012-11-28 0:48 ` David Woodhouse
2012-11-28 8:12 ` Krzysztof Mazur
2012-11-28 9:24 ` David Woodhouse
2012-11-28 9:58 ` Krzysztof Mazur
2012-11-28 10:19 ` David Woodhouse
2012-11-11 22:47 ` Chas Williams (CONTRACTOR)
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