netdev - Re: brcmfmac: rework function picking free BSS index

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Message-Id: <20160609161732.90E20613F6@smtp.codeaurora.org>
Date:	Thu,  9 Jun 2016 16:17:32 +0000 (UTC)
From:	Kalle Valo <kvalo@...eaurora.org>
To:	Rafał Miłecki <zajec5@...il.com>
Cc:	Rafał Miłecki <zajec5@...il.com>,
	Brett Rudley <brudley@...adcom.com>,
	Arend van Spriel <arend@...adcom.com>,
	"Franky (Zhenhui) Lin" <frankyl@...adcom.com>,
	Hante Meuleman <meuleman@...adcom.com>,
	Pieter-Paul Giesberts <pieterpg@...adcom.com>,
	Franky Lin <franky.lin@...adcom.com>,
	linux-wireless@...r.kernel.org (open list:BROADCOM BRCM80211
	IEEE802.11n WIRELESS DRIVER),
	brcm80211-dev-list@...adcom.com (open list:BROADCOM BRCM80211
	IEEE802.11n WIRELESS DRIVER),
	netdev@...r.kernel.org (open list:NETWORKING DRIVERS),
	linux-kernel@...r.kernel.org (open list)
Subject: Re: brcmfmac: rework function picking free BSS index

Rafał Miłecki wrote:
> The old implementation was overcomplicated and slightly bugged in some
> corner cases.
> 
> Consider following state of BSS-es (limited to 6 for simplification):
> drvr->iflist[0]: { bsscfgidx:0, ndev->name:wlan1, }
> drvr->iflist[1]:  (null)
> drvr->iflist[2]: { bsscfgidx:2, ndev->name:wlan1-1, }
> drvr->iflist[3]: { bsscfgidx:3, ndev->name:wlan1-2, }
> drvr->iflist[4]:  (null)
> drvr->iflist[5]:  (null)
> In such case the next AP interface should bsscfgidx 4 (we don't use 1 as
> it's reserved for P2P).
> 
> With old code the loop iterations were following:
> [ifidx = 0] [bsscfgidx = 2] [highest = 2]
> [ifidx = 1] [bsscfgidx = 2] [highest = 2] available = true
> [ifidx = 2] [bsscfgidx = 2] [highest = 2] bsscfgidx = highest + 1
> [ifidx = 3] [bsscfgidx = 3] [highest = 2] bsscfgidx = highest + 1
> [ifidx = 4] [bsscfgidx = 3] [highest = 2] available = true
> [ifidx = 5] [bsscfgidx = 3] [highest = 2] available = true
> There were 2 obvious problems:
> 1) Having empty BSS at index 1 was resulting in available being always
>    set to true, even if we would run out of BSS-es.
> 2) Calculated bsscfgidx was invalid (3 instead of 4) resulting in driver
>    not being able to create the 4th AP interface.
> 
> New code is simpler, placed in file where it's really used, handles
> running out of free BSS-es and allows using 4 interfaces at the same
> time. It also looks for the first free BSS instead of one after the last
> in use. It works well with current driver (which doesn't allow deleting
> interfaces) and should be future proof (if we ever allow deleting).
> 
> Signed-off-by: Rafał Miłecki <zajec5@...il.com>

Thanks, 1 patch applied to wireless-drivers-next.git:

d02fb8f14b2d brcmfmac: rework function picking free BSS index

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https://patchwork.kernel.org/patch/9136421/