Re: [RFT] brcmfmac: add support to move wiphy instance into network namespace

[Johannes Berg <johannes@sipsolutions.net>]

On Fri, 2017-03-17 at 10:06 +0100, Arend Van Spriel wrote:
> On 16-3-2017 22:51, Mark Asselstine wrote:
> > On Tuesday, March 14, 2017 9:51:52 PM EDT Arend van Spriel wrote:
> > > To support network namespace the driver must assure all created
> > > network interfaces are in the same namespace as the wiphy
> > > instance.
> > > 
> > > Reported-by: Mark Asselstine <mark.asselstine@windriver.com>
> > > Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
> > > ---
> > > Hi Mark,
> > > 
> > > Please check this patch. I can not say I am an expert when it
> > > comes
> > > to using namespaces. So let me know if it works and I can change
> > > Reported-by into Tested-by.
> > 
> > Seems to pass the tests I threw at it. Seems happy with namespaces.
> 
> I tested it myself and noticed something unexpected. Upon changing
> from &init_net to brcm-wifi the wdev id has changed from 0x1 to 0x2
> (see below) and upon going from brcm-wifi to &init_net both interface
> change their wdev id.

Interesting. That's clearly a cfg80211 bug, does this help?

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 2e1740c7a8bf..d71d5e90229f 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1183,7 +1183,15 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		INIT_LIST_HEAD(&wdev->mgmt_registrations);
 		spin_lock_init(&wdev->mgmt_registrations_lock);
 
-		wdev->identifier = ++rdev->wdev_id;
+		/*
+		 * We get here also when the interface changes network namespaces,
+		 * as it's registered into the new one, but we don't want it to
+		 * change ID in that case. Checking if the ID is already assigned
+		 * works, because 0 isn't considered a valid ID and the memory is
+		 * 0-initialized.
+		 */
+		if (!wdev->identifier)
+			wdev->identifier = ++rdev->wdev_id;
 		list_add_rcu(&wdev->list, &rdev->wiphy.wdev_list);
 		rdev->devlist_generation++;
 		/* can only change netns with wiphy */

johannes