linux-kernel - [PATCH] solos-pci: Wait for pending TX to complete when releasing vcc

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Date:	Tue, 27 Nov 2012 22:36:23 +0000
From:	David Woodhouse <dwmw2@...radead.org>
To:	chas williams - CONTRACTOR <chas@....nrl.navy.mil>
Cc:	Krzysztof Mazur <krzysiek@...lesie.net>, davem@...emloft.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	nathan@...verse.com.au
Subject: [PATCH] solos-pci: Wait for pending TX to complete when releasing
 vcc

We should no longer be calling the old pop routine for the vcc, after
vcc_release() has completed. Make sure we wait for any pending TX skbs
to complete, by waiting for our own PKT_PCLOSE control skb to be sent.

Signed-off-by: David Woodhouse <David.Woodhouse@...el.com>
---
On Tue, 2012-11-27 at 13:54 -0500, chas williams - CONTRACTOR wrote:
> the driver's close routine should wait for any of the pending tx and
> rx to complete.

Nathan, does this help? I can test here to a certain extent, but when I
use it in PPPoE mode and then crash the router, the DSLAM tends to
refuse to talk to me for an arbitrary period of time after that. Which
is something of a PITA.

diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c
index 9851093..b5bb332 100644
--- a/drivers/atm/solos-pci.c
+++ b/drivers/atm/solos-pci.c
@@ -94,6 +94,7 @@ struct pkt_hdr {
 struct solos_skb_cb {
 	struct atm_vcc *vcc;
 	uint32_t dma_addr;
+	struct completion *c;
 };
 
 
@@ -868,6 +869,7 @@ static void pclose(struct atm_vcc *vcc)
 	struct solos_card *card = vcc->dev->dev_data;
 	struct sk_buff *skb;
 	struct pkt_hdr *header;
+	DECLARE_COMPLETION_ONSTACK(c);
 
 	skb = alloc_skb(sizeof(*header), GFP_ATOMIC);
 	if (!skb) {
@@ -881,11 +883,15 @@ static void pclose(struct atm_vcc *vcc)
 	header->vci = cpu_to_le16(vcc->vci);
 	header->type = cpu_to_le16(PKT_PCLOSE);
 
+	SKB_CB(skb)->c = &c;
+
 	fpga_queue(card, SOLOS_CHAN(vcc->dev), skb, NULL);
 
 	clear_bit(ATM_VF_ADDR, &vcc->flags);
 	clear_bit(ATM_VF_READY, &vcc->flags);
 
+	wait_for_completion(&c);
+
 	/* Hold up vcc_destroy_socket() (our caller) until solos_bh() in the
 	   tasklet has finished processing any incoming packets (and, more to
 	   the point, using the vcc pointer). */
@@ -1011,9 +1017,12 @@ static uint32_t fpga_tx(struct solos_card *card)
 			if (vcc) {
 				atomic_inc(&vcc->stats->tx);
 				solos_pop(vcc, oldskb);
-			} else
+			} else {
+				struct pkt_hdr *header = (void *)oldskb->data;
+				if (le16_to_cpu(header->type) == PKT_PCLOSE)
+					complete(SKB_CB(oldskb)->c);
 				dev_kfree_skb_irq(oldskb);
-
+			}
 		}
 	}
 	/* For non-DMA TX, write the 'TX start' bit for all four ports simultaneously */


-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@...el.com                              Intel Corporation




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