Date: Tue, 04 Jan 2011 15:09:15 +0600 From: Eugene Grosbein <egrosbein@rdtc.ru> To: bschmidt@freebsd.org Cc: freebsd-net@freebsd.org, bug-followup@freebsd.org Subject: Re: kern/153594: [iwn] Network keeps disconnecting when /etc/rc.d/netif restart is run Message-ID: <4D22E3BB.4050703@rdtc.ru> In-Reply-To: <201101041006.06065.bschmidt@freebsd.org> References: <4D22D578.8080903@rdtc.ru> <201101041006.06065.bschmidt@freebsd.org>
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On 04.01.2011 15:06, Bernhard Schmidt wrote: >> Perhaps, wrapping wpa_supplicant invocation into "lockf -t0" would help >> to eliminate race? > > Possibly, but I don't think this is the way to go. > > Currently wpa_supplicant has this code: > /* > * Mark the interface as down to ensure wpa_supplicant has exclusive > * access to the net80211 state machine, do this before opening the > * route socket to avoid a false event that the interface disappeared. > */ > if (getifflags(drv, &flags) == 0) > (void) setifflags(drv, flags &~ IFF_UP); > > This code works such that it will send an event to already running > wpa_supplicant instances which will then terminate. This does indeed work if > there's enough delay between invocations, though, if there is just a small > delay (~100ms or something), that event doesn't get passed probably. I think > we should start looking into possible solution at that point, trying to figure > out why the the event doesn't get passed (probably because the interface is > not yet up at that point) will get us closer to proper solution. Proper fine-grained locking was always good solution for race problem :-) How about using flock(2) in wpa_supplicant source code? Eugene Grosbein
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