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From: Jouni Malinen <j@w1.fi>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Arik Nemtsov <arik@wizery.com>,
	linux-wireless@vger.kernel.org, Luciano Coelho <coelho@ti.com>
Subject: Re: [PATCH 02/10] wl12xx: AP-mode - fix race condition on sta connection
Date: Thu, 27 Jan 2011 02:20:34 +0200	[thread overview]
Message-ID: <20110127002034.GA18234@jm.kir.nu> (raw)
In-Reply-To: <1296079719.3635.47.camel@jlt3.sipsolutions.net>

On Wed, Jan 26, 2011 at 11:08:39PM +0100, Johannes Berg wrote:
> If we add the station before the response frame's ACK is received, we
> still have the race, and we need to delete if we don't get the ACK. If
> we add the station before we send the assoc response we get rid of this
> race, but also have to delete if we don't get the ACK. I guess that case
> is actually nicer in some way since we would have allowed the station to
> connect, so if spurious data frames go up because we don't get an ACK
> from the station that's no big deal?

>From the correctness view point, the STA entry would need to be enabled
(added/marked associated) at the moment the ACK frame is received. Since
we do some internal processing between kernel and user space, there is
obviously some latency involved. The most correct mechanism would be to
make hostapd add a not-associated-STA entry before sending association
response with status code 0 and request mac80211 to mark it associated
automatically on TX status report (showing success) from the driver.
However, for practical purposes, that may be too complex and doing what
you describe above is likely good enough.

-- 
Jouni Malinen                                            PGP id EFC895FA

  parent reply	other threads:[~2011-01-27  0:20 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-16  5:42 [PATCH 00/10] wl12xx: AP-mode per link PSM Arik Nemtsov
2011-01-16  5:42 ` [PATCH 01/10] wl12xx: fix potential race condition with TX queue watermark Arik Nemtsov
2011-01-16  5:42 ` [PATCH 02/10] wl12xx: AP-mode - fix race condition on sta connection Arik Nemtsov
2011-01-26 14:01   ` Luciano Coelho
2011-01-26 20:04     ` Arik Nemtsov
2011-01-26 21:28       ` Luciano Coelho
2011-01-26 21:33   ` Johannes Berg
2011-01-26 21:44     ` Arik Nemtsov
2011-01-26 21:54       ` Johannes Berg
2011-01-26 22:02         ` Arik Nemtsov
2011-01-26 22:08           ` Johannes Berg
2011-01-26 22:16             ` Arik Nemtsov
2011-01-26 23:11               ` Johannes Berg
2011-01-27  0:20             ` Jouni Malinen [this message]
2011-01-27  8:21               ` Johannes Berg
2011-01-16  5:42 ` [PATCH 03/10] wl12xx: AP-mode - TX queue per link in AC Arik Nemtsov
2011-01-16  5:42 ` [PATCH 04/10] mac80211: do not calc frame duration when using HW rate-control Arik Nemtsov
2011-01-16  8:34   ` Johannes Berg
2011-01-16  5:42 ` [PATCH 05/10] wl12xx: report invalid TX rate when returning non-TX-ed skbs Arik Nemtsov
2011-01-27  9:51   ` Luciano Coelho
2011-01-27 10:33     ` Johannes Berg
2011-01-30  6:57       ` Arik Nemtsov
2011-01-16  5:42 ` [PATCH 06/10] mac80211: add HW flag for disabling auto link-PS in AP mode Arik Nemtsov
2011-01-16  8:50   ` Johannes Berg
     [not found]     ` <AANLkTik=WDsehr0EgW7QemfdmokvaLzg1ugASwiuCOXt@mail.gmail.com>
2011-01-16 21:53       ` Fwd: " Arik Nemtsov
2011-01-17  9:35         ` Johannes Berg
2011-01-17 22:47           ` Arik Nemtsov
2011-01-18  9:05             ` Johannes Berg
2011-01-18 19:17               ` Arik Nemtsov
2011-01-27 11:39   ` Luciano Coelho
2011-01-16  5:42 ` [PATCH 07/10] wl12xx: AP-mode - support HW based link PS monitoring Arik Nemtsov
2011-01-27 11:41   ` Luciano Coelho
2011-01-16  5:42 ` [PATCH 08/10] wl12xx: AP mode - fix bug in cleanup of wl1271_op_sta_add() Arik Nemtsov
2011-01-16  5:42 ` [PATCH 09/10] wl12xx: AP-mode - count free FW TX blocks per link Arik Nemtsov
2011-01-16  5:42 ` [PATCH 10/10] wl12xx: AP-mode - management of links in PS-mode Arik Nemtsov

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