[OpenWrt-Devel,2/2] kernel: atm: pppoatm fix vc-mux connection failures

diff --git a/target/linux/generic/backport-4.14/080-net-convert-sock.sk_wmem_alloc-from-atomic_t-to-refc.patch b/target/linux/generic/backport-4.14/080-net-convert-sock.sk_wmem_alloc-from-atomic_t-to-refc.patch
new file mode 100644
index 0000000000..8108d99348
--- /dev/null
+++ b/target/linux/generic/backport-4.14/080-net-convert-sock.sk_wmem_alloc-from-atomic_t-to-refc.patch
@@ -0,0 +1,186 @@ 
+From 99967eb67d14b2ed17b194a8dac357d641a06e43 Mon Sep 17 00:00:00 2001
+From: David Woodhouse <dwmw2@infradead.org>
+Date: Fri, 15 Jun 2018 21:00:27 +0100
+Subject: [PATCH] net: convert sock.sk_wmem_alloc from atomic_t to refcount_t
+
+On Fri, 2018-06-15 at 14:44 +0100, David Woodhouse wrote:
+>
+> > Or simply use a new field in ATM_SKB(skb) to remember a stable
+> > truesize used in both sides (add/sub)
+>
+> Right, that was my second suggestion ("copy the accounted value...").
+>
+> It's a bit of a hack, and I think that actually *using* sock_wfree()
+> instead of what's currently in atm_pop_raw() would be the better
+> solution. Does anyone remember why we didn't do that in the first
+> place?
+
+That does end up being quite hairy. I don't think it's worth doing.
+
+This should probably suffice to fix it...
+
+Kevin this is going to conflict with the ifx_atm_alloc_skb() hack in
+the tree you're working on, but that needs to be killed with fire
+anyway. It's utterly pointless as discussed.
+
+From 3368eaeb0a2f09138894dde0f26f879e5228005a Mon Sep 17 00:00:00 2001
+From: David Woodhouse <dwmw2@infradead.org>
+Date: Fri, 15 Jun 2018 20:49:20 +0100
+Subject: [PATCH] atm: Preserve value of skb->truesize when accounting to vcc
+
+There's a hack in pskb_expand_head() to avoid adjusting skb->truesize
+for certain skbs. Ideally it would cover ATM too. It doesn't. Just
+stashing the accounted value and using it in atm_raw_pop() is probably
+the easiest way to cope.
+
+Signed-off-by: David Woodhouse <dwmw2@infradead.org>
+Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
+---
+ include/linux/atmdev.h | 15 +++++++++++++++
+ net/atm/br2684.c       |  3 +--
+ net/atm/clip.c         |  3 +--
+ net/atm/common.c       |  3 +--
+ net/atm/lec.c          |  3 +--
+ net/atm/mpc.c          |  3 +--
+ net/atm/pppoatm.c      |  3 +--
+ net/atm/raw.c          |  4 ++--
+ 8 files changed, 23 insertions(+), 14 deletions(-)
+
+diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h
+index 0c27515d..8124815e 100644
+--- a/include/linux/atmdev.h
++++ b/include/linux/atmdev.h
+@@ -214,6 +214,7 @@ struct atmphy_ops {
+ struct atm_skb_data {
+ 	struct atm_vcc	*vcc;		/* ATM VCC */
+ 	unsigned long	atm_options;	/* ATM layer options */
++	unsigned int	acct_truesize;  /* truesize accounted to vcc */
+ };
+ 
+ #define VCC_HTABLE_SIZE 32
+@@ -241,6 +242,20 @@ void vcc_insert_socket(struct sock *sk);
+ 
+ void atm_dev_release_vccs(struct atm_dev *dev);
+ 
++static inline void atm_account_tx(struct atm_vcc *vcc, struct sk_buff *skb)
++{
++	/*
++	 * Because ATM skbs may not belong to a sock (and we don't
++	 * necessarily want to), skb->truesize may be adjusted,
++	 * escaping the hack in pskb_expand_head() which avoids
++	 * doing so for some cases. So stash the value of truesize
++	 * at the time we accounted it, and atm_pop_raw() can use
++	 * that value later, in case it changes.
++	 */
++	refcount_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
++	ATM_SKB(skb)->acct_truesize = skb->truesize;
++	ATM_SKB(skb)->atm_options = vcc->atm_options;
++}
+ 
+ static inline void atm_force_charge(struct atm_vcc *vcc,int truesize)
+ {
+diff --git a/net/atm/br2684.c b/net/atm/br2684.c
+index 4e111196..bc21f8e8 100644
+--- a/net/atm/br2684.c
++++ b/net/atm/br2684.c
+@@ -252,8 +252,7 @@ static int br2684_xmit_vcc(struct sk_buff *skb, struct net_device *dev,
+ 
+ 	ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc;
+ 	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, atmvcc, atmvcc->dev);
+-	refcount_add(skb->truesize, &sk_atm(atmvcc)->sk_wmem_alloc);
+-	ATM_SKB(skb)->atm_options = atmvcc->atm_options;
++	atm_account_tx(atmvcc, skb);
+ 	dev->stats.tx_packets++;
+ 	dev->stats.tx_bytes += skb->len;
+ 
+diff --git a/net/atm/clip.c b/net/atm/clip.c
+index 65f706e4..60920a42 100644
+--- a/net/atm/clip.c
++++ b/net/atm/clip.c
+@@ -381,8 +381,7 @@ static netdev_tx_t clip_start_xmit(struct sk_buff *skb,
+ 		memcpy(here, llc_oui, sizeof(llc_oui));
+ 		((__be16 *) here)[3] = skb->protocol;
+ 	}
+-	refcount_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
+-	ATM_SKB(skb)->atm_options = vcc->atm_options;
++	atm_account_tx(vcc, skb);
+ 	entry->vccs->last_use = jiffies;
+ 	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, vcc, vcc->dev);
+ 	old = xchg(&entry->vccs->xoff, 1);	/* assume XOFF ... */
+diff --git a/net/atm/common.c b/net/atm/common.c
+index 83d6f40e..9935cc1f 100644
+--- a/net/atm/common.c
++++ b/net/atm/common.c
+@@ -633,10 +633,9 @@ int vcc_sendmsg(struct socket *sock, struct msghdr *m, size_t size)
+ 		goto out;
+ 	}
+ 	pr_debug("%d += %d\n", sk_wmem_alloc_get(sk), skb->truesize);
+-	refcount_add(skb->truesize, &sk->sk_wmem_alloc);
++	atm_account_tx(vcc, skb);
+ 
+ 	skb->dev = NULL; /* for paths shared with net_device interfaces */
+-	ATM_SKB(skb)->atm_options = vcc->atm_options;
+ 	if (!copy_from_iter_full(skb_put(skb, size), size, &m->msg_iter)) {
+ 		kfree_skb(skb);
+ 		error = -EFAULT;
+diff --git a/net/atm/lec.c b/net/atm/lec.c
+index 5741b647..9f236569 100644
+--- a/net/atm/lec.c
++++ b/net/atm/lec.c
+@@ -182,9 +182,8 @@ lec_send(struct atm_vcc *vcc, struct sk_buff *skb)
+ 	struct net_device *dev = skb->dev;
+ 
+ 	ATM_SKB(skb)->vcc = vcc;
+-	ATM_SKB(skb)->atm_options = vcc->atm_options;
++	atm_account_tx(vcc, skb);
+ 
+-	refcount_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
+ 	if (vcc->send(vcc, skb) < 0) {
+ 		dev->stats.tx_dropped++;
+ 		return;
+diff --git a/net/atm/mpc.c b/net/atm/mpc.c
+index 56771472..db9a1838 100644
+--- a/net/atm/mpc.c
++++ b/net/atm/mpc.c
+@@ -555,8 +555,7 @@ static int send_via_shortcut(struct sk_buff *skb, struct mpoa_client *mpc)
+ 					sizeof(struct llc_snap_hdr));
+ 	}
+ 
+-	refcount_add(skb->truesize, &sk_atm(entry->shortcut)->sk_wmem_alloc);
+-	ATM_SKB(skb)->atm_options = entry->shortcut->atm_options;
++	atm_account_tx(entry->shortcut, skb);
+ 	entry->shortcut->send(entry->shortcut, skb);
+ 	entry->packets_fwded++;
+ 	mpc->in_ops->put(entry);
+diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
+index 21d9d341..af8c4b38 100644
+--- a/net/atm/pppoatm.c
++++ b/net/atm/pppoatm.c
+@@ -350,8 +350,7 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
+ 		return 1;
+ 	}
+ 
+-	refcount_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc);
+-	ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
++	atm_account_tx(vcc, skb);
+ 	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n",
+ 		 skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev);
+ 	ret = ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
+diff --git a/net/atm/raw.c b/net/atm/raw.c
+index ee10e8d4..b3ba44aa 100644
+--- a/net/atm/raw.c
++++ b/net/atm/raw.c
+@@ -35,8 +35,8 @@ static void atm_pop_raw(struct atm_vcc *vcc, struct sk_buff *skb)
+ 	struct sock *sk = sk_atm(vcc);
+ 
+ 	pr_debug("(%d) %d -= %d\n",
+-		 vcc->vci, sk_wmem_alloc_get(sk), skb->truesize);
+-	WARN_ON(refcount_sub_and_test(skb->truesize, &sk->sk_wmem_alloc));
++		 vcc->vci, sk_wmem_alloc_get(sk), ATM_SKB(skb)->acct_truesize);
++	WARN_ON(refcount_sub_and_test(ATM_SKB(skb)->acct_truesize, &sk->sk_wmem_alloc));
+ 	dev_kfree_skb_any(skb);
+ 	sk->sk_write_space(sk);
+ }
+-- 
+2.15.1 (Apple Git-101)
+