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SubjectRe: [PATCH 1/1] net: Add rtnl_lock for netif_device_attach/detach
Hello.

On 04/16/2014 11:08 AM, Li, Zhen-Hua wrote:

> From: "Li, Zhen-Hua" <zhen-hual@hp.com>

> As netif_running is called in netif_device_attach/detach. There should be
> rtnl_lock/unlock called, to avoid dev stat change during netif_device_attach
> and detach being called.
> I checked NIC some drivers, some of them have netif_device_attach/detach
> called between rtnl_lock/unlock, while some drivers do not.

> This patch is tring to find a generic way to fix this for all NIC drivers.

> Signed-off-by: Li, Zhen-Hua <zhen-hual@hp.com>
> ---
> net/core/dev.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)

> diff --git a/net/core/dev.c b/net/core/dev.c
> index 5b3042e..795bbc5 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2190,10 +2190,19 @@ EXPORT_SYMBOL(__dev_kfree_skb_any);
> */
> void netif_device_detach(struct net_device *dev)
> {
> + /**

Hm, why kernel-doc style comment here?

> + * As netif_running is called , rtnl_lock and unlock are needed to
> + * avoid __LINK_STATE_START bit changes during this function call.
> + */
> + int need_unlock;
> +
> + need_unlock = rtnl_trylock();
> if (test_and_clear_bit(__LINK_STATE_PRESENT, &dev->state) &&
> netif_running(dev)) {
> netif_tx_stop_all_queues(dev);
> }
> + if (need_unlock)
> + rtnl_unlock();
> }
> EXPORT_SYMBOL(netif_device_detach);
>
> @@ -2205,11 +2214,20 @@ EXPORT_SYMBOL(netif_device_detach);
> */
> void netif_device_attach(struct net_device *dev)
> {
> + /**

... and here?

> + * As netif_running is called , rtnl_lock and unlock are needed to
> + * avoid __LINK_STATE_START bit changes during this function call.
> + */

WBR, Sergei



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