[PATCH] TI Davinci EMAC : Fix Console Hang when bringing the interface down

[PATCH] TI Davinci EMAC : Fix Console Hang when bringing the interface down

[Sriramakrishnan]

In the NAPI poll function(emac_poll), check for netif_running()
is unnecassary. In addition to associated runtime overhead, it
also results in a continuous softirq loop when the interface is
brought down under heavy traffic(tested wit Traffic Generator).
Once the interface is disabled, the poll function always returns
zero(with the check for netif_running) and napi_complete() would
never get called resulting in softirq loop.

Signed-off-by: Sriramakrishnan <srk@ti.com>
Acked-by: Chaithrika U S <chaithrika@ti.com>
---
This patch has been validated on the OMAP-L138 platform. The smsc911x
driver has a similar issue. Will post a patch for that separately.

 drivers/net/davinci_emac.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/drivers/net/davinci_emac.c b/drivers/net/davinci_emac.c
index f72c56d..2533413 100644
--- a/drivers/net/davinci_emac.c
+++ b/drivers/net/davinci_emac.c
@@ -2140,9 +2140,6 @@ static int emac_poll(struct napi_struct *napi, int budget)
 	u32 status = 0;
 	u32 num_pkts = 0;
 
-	if (!netif_running(ndev))
-		return 0;
-
 	/* Check interrupt vectors and call packet processing */
 	status = emac_read(EMAC_MACINVECTOR);
 
-- 
1.6.2.4

Re: [PATCH] TI Davinci EMAC : Fix Console Hang when bringing the interface down

[David Miller]

From: Sriramakrishnan <srk@ti.com>
Date: Thu, 12 Nov 2009 17:25:42 +0530

> In the NAPI poll function(emac_poll), check for netif_running()
> is unnecassary. In addition to associated runtime overhead, it
> also results in a continuous softirq loop when the interface is
> brought down under heavy traffic(tested wit Traffic Generator).
> Once the interface is disabled, the poll function always returns
> zero(with the check for netif_running) and napi_complete() would
> never get called resulting in softirq loop.
> 
> Signed-off-by: Sriramakrishnan <srk@ti.com>
> Acked-by: Chaithrika U S <chaithrika@ti.com>

Applied to net-2.6