linux-kernel - Re: [PATCH v3 8/7] pppoatm: fix missing wakeup in pppoatm

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Date:	Sun, 11 Nov 2012 11:39:53 +0000
From:	David Woodhouse <dwmw2@...radead.org>
To:	Krzysztof Mazur <krzysiek@...lesie.net>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Chas Williams - CONTRACTOR <chas@....nrl.navy.mil>,
	davem@...emloft.net
Subject: Re: [PATCH v3 8/7] pppoatm: fix missing wakeup in pppoatm_send()

On Sun, 2012-11-11 at 12:04 +0100, Krzysztof Mazur wrote:
> Yes, but socket can be also locked for a long time, vcc_sendmsg() sleeps
> owning socket lock waiting for memory or atm_may_send().

Right. Something like this then, instead of my previous patch 8/7?

Only addresses the sock_owned_by_user() case and not ATM_VF_RELEASED,
ATM_VF_CLOSE or !ATM_VF_READY, but your amended patch 6 fixes that I
think.

diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h
index 31c16c6..59532ed 100644
--- a/include/linux/atmdev.h
+++ b/include/linux/atmdev.h
@@ -308,6 +308,7 @@ struct atm_vcc {
 	struct atm_dev	*dev;		/* device back pointer */
 	struct atm_qos	qos;		/* QOS */
 	struct atm_sap	sap;		/* SAP */
+	void (*unlock_cb)(struct atm_vcc *vcc); /* release_sock callback */
 	void (*push)(struct atm_vcc *vcc,struct sk_buff *skb);
 	void (*pop)(struct atm_vcc *vcc,struct sk_buff *skb); /* optional */
 	int (*push_oam)(struct atm_vcc *vcc,void *cell);
diff --git a/net/atm/common.c b/net/atm/common.c
index ea952b2..c212016 100644
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -126,10 +126,19 @@ static void vcc_write_space(struct sock *sk)
 	rcu_read_unlock();
 }
 
+static void vcc_unlock_cb(struct sock *sk)
+{
+	struct atm_vcc *vcc = atm_sk(sk);
+
+	if (vcc->unlock_cb)
+		vcc->unlock_cb(vcc);
+}
+
 static struct proto vcc_proto = {
 	.name	  = "VCC",
 	.owner	  = THIS_MODULE,
 	.obj_size = sizeof(struct atm_vcc),
+	.release_cb = vcc_unlock_cb,
 };
 
 int vcc_create(struct net *net, struct socket *sock, int protocol, int family)
@@ -158,6 +167,7 @@ int vcc_create(struct net *net, struct socket *sock, int protocol, int family)
 	vcc->pop = NULL;
 	vcc->owner = NULL;
 	vcc->push_oam = NULL;
+	vcc->unlock_cb = NULL;
 	vcc->vpi = vcc->vci = 0; /* no VCI/VPI yet */
 	vcc->atm_options = vcc->aal_options = 0;
 	sk->sk_destruct = vcc_sock_destruct;
diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
index 7507c20..751569a 100644
--- a/net/atm/pppoatm.c
+++ b/net/atm/pppoatm.c
@@ -60,6 +60,7 @@ struct pppoatm_vcc {
 	struct atm_vcc	*atmvcc;	/* VCC descriptor */
 	void (*old_push)(struct atm_vcc *, struct sk_buff *);
 	void (*old_pop)(struct atm_vcc *, struct sk_buff *);
+	void (*old_unlock_cb)(struct atm_vcc *);
 	struct module *old_owner;
 					/* keep old push/pop for detaching */
 	enum pppoatm_encaps encaps;
@@ -108,6 +109,14 @@ static void pppoatm_wakeup_sender(unsigned long arg)
 	ppp_output_wakeup((struct ppp_channel *) arg);
 }
 
+static void pppoatm_unlock_cb(struct atm_vcc *atmvcc)
+{
+	struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
+
+	tasklet_schedule(&pvcc->wakeup_tasklet);
+	if (pvcc->old_unlock_cb)
+		pvcc->old_unlock_cb(atmvcc);
+}
 /*
  * This gets called every time the ATM card has finished sending our
  * skb.  The ->old_pop will take care up normal atm flow control,
@@ -152,6 +161,7 @@ static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
 	pvcc = atmvcc_to_pvcc(atmvcc);
 	atmvcc->push = pvcc->old_push;
 	atmvcc->pop = pvcc->old_pop;
+	atmvcc->unlock_cb = pvcc->old_unlock_cb;
 	tasklet_kill(&pvcc->wakeup_tasklet);
 	ppp_unregister_channel(&pvcc->chan);
 	atmvcc->user_back = NULL;
@@ -385,6 +395,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
 	pvcc->old_push = atmvcc->push;
 	pvcc->old_pop = atmvcc->pop;
 	pvcc->old_owner = atmvcc->owner;
+	pvcc->old_unlock_cb = atmvcc->unlock_cb;
 	pvcc->encaps = (enum pppoatm_encaps) be.encaps;
 	pvcc->chan.private = pvcc;
 	pvcc->chan.ops = &pppoatm_ops;


-- 
dwmw2


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