[source] rb532: Backport fix to resolve oops during korina_restart

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/002264d5b1ac6e6d04b1dd569060de8ce03aa272

commit 002264d5b1ac6e6d04b1dd569060de8ce03aa272
Author: Florian Fainelli <f.fainelli at gmail.com>
AuthorDate: Fri Dec 23 20:35:59 2016 -0800

    rb532: Backport fix to resolve oops during korina_restart
    
    Signed-off-by: Florian Fainelli <f.fainelli at gmail.com>
---
 .../patches-4.4/100-korina_fix_napi_disable.patch  | 56 ++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/target/linux/rb532/patches-4.4/100-korina_fix_napi_disable.patch b/target/linux/rb532/patches-4.4/100-korina_fix_napi_disable.patch
new file mode 100644
index 0000000..3f80e09
--- /dev/null
+++ b/target/linux/rb532/patches-4.4/100-korina_fix_napi_disable.patch
@@ -0,0 +1,56 @@
+From 5833532b49820aa221248f296c207cc50d20ca2d Mon Sep 17 00:00:00 2001
+From: Florian Fainelli <f.fainelli at gmail.com>
+Date: Fri, 23 Dec 2016 19:36:31 -0800
+Subject: [PATCH net] net: korina: Fix NAPI versus resources freeing
+
+Commit beb0babfb77e ("korina: disable napi on close and restart")
+introduced calls to napi_disable() that were missing before,
+unfortunately this leaves a small window during which NAPI has a chance
+to run, yet we just freed resources since korina_free_ring() has been
+called:
+
+Fix this by disabling NAPI first then freeing resource, and make sure
+that we also cancel the restart taks before doing the resource freeing.
+
+Fixes: beb0babfb77e ("korina: disable napi on close and restart")
+Reported-by: Alexandros C. Couloumbis <alex at ozo.com>
+Signed-off-by: Florian Fainelli <f.fainelli at gmail.com>
+---
+ drivers/net/ethernet/korina.c | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/drivers/net/ethernet/korina.c b/drivers/net/ethernet/korina.c
+index cbeea915f026..8037426ec50f 100644
+--- a/drivers/net/ethernet/korina.c
++++ b/drivers/net/ethernet/korina.c
+@@ -900,10 +900,10 @@ static void korina_restart_task(struct work_struct *work)
+ 				DMA_STAT_DONE | DMA_STAT_HALT | DMA_STAT_ERR,
+ 				&lp->rx_dma_regs->dmasm);
+ 
+-	korina_free_ring(dev);
+-
+ 	napi_disable(&lp->napi);
+ 
++	korina_free_ring(dev);
++
+ 	if (korina_init(dev) < 0) {
+ 		printk(KERN_ERR "%s: cannot restart device\n", dev->name);
+ 		return;
+@@ -1064,12 +1064,12 @@ static int korina_close(struct net_device *dev)
+ 	tmp = tmp | DMA_STAT_DONE | DMA_STAT_HALT | DMA_STAT_ERR;
+ 	writel(tmp, &lp->rx_dma_regs->dmasm);
+ 
+-	korina_free_ring(dev);
+-
+ 	napi_disable(&lp->napi);
+ 
+ 	cancel_work_sync(&lp->restart_task);
+ 
++	korina_free_ring(dev);
++
+ 	free_irq(lp->rx_irq, dev);
+ 	free_irq(lp->tx_irq, dev);
+ 	free_irq(lp->ovr_irq, dev);
+-- 
+2.9.3
+