[PATCH] net-next: korina: Fix NAPI versus resources freeing

[PATCH] net-next: korina: Fix NAPI versus resources freeing

[John Crispin]

From: Florian Fainelli <f.fainelli@gmail.com>

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@ozo.com>
Tested-by: John Crispin <john@phrozen.org>
Signed-off-by: Florian Fainelli <f.fainelli@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 1799fe1..c051987 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);
-- 
1.7.10.4

Re: [PATCH] net-next: korina: Fix NAPI versus resources freeing

[Florian Fainelli]

On 01/04/2017 01:31 AM, John Crispin wrote:
> From: Florian Fainelli <f.fainelli@gmail.com>
> 
> 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")

I submitted this patch to 'net' already, but thanks for doing it!
-- 
Florian