Messages in this thread | | | Date | Mon, 21 Apr 2014 14:30:06 +0800 | From | "Li, ZhenHua" <> | Subject | Re: [PATCH 1/1] net: Add rtnl_lock for netif_device_attach/detach |
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The comment is trying to explain why add a lock here.
On 04/19/2014 03:01 AM, Sergei Shtylyov wrote: > 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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