[PATCH] mac80211: Fix IBSS merge

[PATCH] mac80211: Fix IBSS merge

[Sujith]

Currently, in IBSS mode, a single creator would go into
a loop trying to merge/scan. This happens because the IBSS timer is
rearmed on finishing a scan and the subsequent
timer invocation requests another scan immediately.

This patch fixes this issue by checking if we have just completed
a scan run trying to merge with other IBSS networks.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
---
 net/mac80211/ibss.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index f1362f3..fbffce9 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -455,6 +455,10 @@ static void ieee80211_sta_merge_ibss(struct ieee80211_sub_if_data *sdata)
 
 	ieee80211_sta_expire(sdata, IEEE80211_IBSS_INACTIVITY_LIMIT);
 
+	if (time_before(jiffies, ifibss->last_scan_completed +
+		       IEEE80211_IBSS_MERGE_INTERVAL))
+		return;
+
 	if (ieee80211_sta_active_ibss(sdata))
 		return;
 
-- 
1.6.5.2

Re: [PATCH] mac80211: Fix IBSS merge

[Johannes Berg]

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On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
> Currently, in IBSS mode, a single creator would go into
> a loop trying to merge/scan. This happens because the IBSS timer is
> rearmed on finishing a scan and the subsequent
> timer invocation requests another scan immediately.
> 
> This patch fixes this issue by checking if we have just completed
> a scan run trying to merge with other IBSS networks.

Heh, how many people do we need to fix IBSS? :)

Looks sane to me.

johannes

> Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
> ---
>  net/mac80211/ibss.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
> index f1362f3..fbffce9 100644
> --- a/net/mac80211/ibss.c
> +++ b/net/mac80211/ibss.c
> @@ -455,6 +455,10 @@ static void ieee80211_sta_merge_ibss(struct ieee80211_sub_if_data *sdata)
>  
>  	ieee80211_sta_expire(sdata, IEEE80211_IBSS_INACTIVITY_LIMIT);
>  
> +	if (time_before(jiffies, ifibss->last_scan_completed +
> +		       IEEE80211_IBSS_MERGE_INTERVAL))
> +		return;
> +
>  	if (ieee80211_sta_active_ibss(sdata))
>  		return;
>  


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Re: [PATCH] mac80211: Fix IBSS merge

[Sujith]

Johannes Berg wrote:
> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
> > Currently, in IBSS mode, a single creator would go into
> > a loop trying to merge/scan. This happens because the IBSS timer is
> > rearmed on finishing a scan and the subsequent
> > timer invocation requests another scan immediately.
> > 
> > This patch fixes this issue by checking if we have just completed
> > a scan run trying to merge with other IBSS networks.
> 
> Heh, how many people do we need to fix IBSS? :)
> 
> Looks sane to me.

Thanks.

And I encountered an oops when using iwlwifi (current wireless-testing).
Set the interface mode to Ad-hoc, bring up the interface and issue a join
command using iw - this causes the panic.

Trace:

[16265.474794] BUG: unable to handle kernel NULL pointer dereference at (null)
[16265.477752] IP: [<ffffffffa03faa96>] iwl_mac_hw_scan+0xf6/0x650 [iwlcore]
[16265.477752] PGD 0
[16265.477752] Oops: 0000 [#1] PREEMPT SMP
[16265.477752] last sysfs file: /sys/class/firmware/0000:05:00.0/loading
[16265.477752] CPU 1
[16265.477752] Modules linked in: iwlagn iwlcore mac80211 cfg80211 arc4 ecb i915 drm_kms_helper drm i2c_algo_bit pcmcia thinkpad_acpi rfkill led_class parport_]
[16265.477752] Pid: 3864, comm: phy0 Tainted: G        W  2.6.32-rc5-wl #60 7661GN4
[16265.477752] RIP: 0010:[<ffffffffa03faa96>]  [<ffffffffa03faa96>] iwl_mac_hw_scan+0xf6/0x650 [iwlcore]
[16265.477752] RSP: 0018:ffff880077f8bc20  EFLAGS: 00010002
[16265.477752] RAX: 0000000000000001 RBX: ffff880077e61660 RCX: 0000000000000000
[16265.477752] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00000000000013e4
[16265.477752] RBP: ffff880077f8bc60 R08: 0000000000000001 R09: ffffffff8142f0df
[16265.477752] R10: ffff88007b836090 R11: 0000000000000046 R12: ffff88007b8f3000
[16265.477752] R13: ffff880077e62098 R14: ffff880077e62008 R15: 0000000000000286
[16265.477752] FS:  0000000000000000(0000) GS:ffff880002100000(0000) knlGS:0000000000000000
[16265.477752] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[16265.477752] CR2: 0000000000000000 CR3: 0000000001001000 CR4: 00000000000006e0
[16265.477752] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[16265.477752] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[16265.477752] Process phy0 (pid: 3864, threadinfo ffff880077f8a000, task ffff88007b835a00)
[16265.477752] Stack:
[16265.477752]  ffff880077f8bc50 ffffffff81046497 ffff880077e60520 ffff880077e60520
[16265.477752] <0> ffff880077e61250 ffff88007b8f3000 ffff880077e60520 0000000000000009
[16265.477752] <0> ffff880077f8bcb0 ffffffffa0380506 2222222222222222 2222222222222222
[16265.477752] Call Trace:
[16265.477752]  [<ffffffff81046497>] ? warn_slowpath_common+0x87/0xb0
[16265.477752]  [<ffffffffa0380506>] __ieee80211_start_scan+0xe6/0x3e0 [mac80211]
[16265.477752]  [<ffffffffa03808be>] ieee80211_request_internal_scan+0xbe/0xc0 [mac80211]
[16265.477752]  [<ffffffffa0385138>] ieee80211_ibss_work+0x708/0x800 [mac80211]
[16265.477752]  [<ffffffffa0384a30>] ? ieee80211_ibss_work+0x0/0x800 [mac80211]
[16265.477752]  [<ffffffff8105ef2e>] worker_thread+0x22e/0x420
[16265.477752]  [<ffffffff8105eedd>] ? worker_thread+0x1dd/0x420
[16265.477752]  [<ffffffff8132a3fd>] ? thread_return+0x585/0x8b8
[16265.477752]  [<ffffffff81063fb0>] ? autoremove_wake_function+0x0/0x40
[16265.477752]  [<ffffffff8105ed00>] ? worker_thread+0x0/0x420
[16265.477752]  [<ffffffff81063b9e>] kthread+0x8e/0xa0
[16265.477752]  [<ffffffff8100cf3a>] child_rip+0xa/0x20
[16265.477752]  [<ffffffff8100c8c0>] ? restore_args+0x0/0x30
[16265.477752]  [<ffffffff81063b10>] ? kthread+0x0/0xa0
[16265.477752]  [<ffffffff8100cf30>] ? child_rip+0x0/0x20
[16265.477752] Code: 09 00 00 00 00 00 00 41 8b 54 24 0c 85 d2 74 30 31 d2 31 c0 be 01 00 00 00 0f 1f 40 00 48 63 c8 49 89 f0 83 c0 01 49 8b 4c cc 38 <8b> 09 4
[16265.477752] RIP  [<ffffffffa03faa96>] iwl_mac_hw_scan+0xf6/0x650 [iwlcore]
[16265.477752]  RSP <ffff880077f8bc20>
[16265.477752] CR2: 0000000000000000
[16265.477752] ---[ end trace 1787d9867e43487e ]---

Re: [PATCH] mac80211: Fix IBSS merge

[Johannes Berg]

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On Mon, 2009-11-02 at 14:48 +0530, Sujith wrote:

> And I encountered an oops when using iwlwifi (current wireless-testing).
> Set the interface mode to Ad-hoc, bring up the interface and issue a join
> command using iw - this causes the panic.

Hmm, interesting, I'll take a look. I guess I suspect
e1e8e5389a7b947a212c0d9db1b4e18eef16946e

johannes


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Re: [PATCH] mac80211: Fix IBSS merge

[John W. Linville]

On Mon, Nov 02, 2009 at 09:44:46AM +0100, Johannes Berg wrote:
> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
> > Currently, in IBSS mode, a single creator would go into
> > a loop trying to merge/scan. This happens because the IBSS timer is
> > rearmed on finishing a scan and the subsequent
> > timer invocation requests another scan immediately.
> > 
> > This patch fixes this issue by checking if we have just completed
> > a scan run trying to merge with other IBSS networks.
> 
> Heh, how many people do we need to fix IBSS? :)

Yeah, no kidding...I suspect that actual IBSS users are few, and a
substantial number of those are doing crazy things with it! :-)

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

Re: [PATCH] mac80211: Fix IBSS merge

[Felix Fietkau]

John W. Linville wrote:
> On Mon, Nov 02, 2009 at 09:44:46AM +0100, Johannes Berg wrote:
>> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
>> > Currently, in IBSS mode, a single creator would go into
>> > a loop trying to merge/scan. This happens because the IBSS timer is
>> > rearmed on finishing a scan and the subsequent
>> > timer invocation requests another scan immediately.
>> > 
>> > This patch fixes this issue by checking if we have just completed
>> > a scan run trying to merge with other IBSS networks.
>> 
>> Heh, how many people do we need to fix IBSS? :)
> 
> Yeah, no kidding...I suspect that actual IBSS users are few, and a
> substantial number of those are doing crazy things with it! :-)
Yeah, we're doing crazy things like mesh networks of few hundred
nodes... something that 11s isn't really suitable for. :-)

- Felix

Re: [PATCH] mac80211: Fix IBSS merge

[Luis R. Rodriguez]

On Mon, Nov 2, 2009 at 9:20 AM, Felix Fietkau <nbd@nbd.name> wrote:
> John W. Linville wrote:
>> On Mon, Nov 02, 2009 at 09:44:46AM +0100, Johannes Berg wrote:
>>> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
>>> > Currently, in IBSS mode, a single creator would go into
>>> > a loop trying to merge/scan. This happens because the IBSS timer is
>>> > rearmed on finishing a scan and the subsequent
>>> > timer invocation requests another scan immediately.
>>> >
>>> > This patch fixes this issue by checking if we have just completed
>>> > a scan run trying to merge with other IBSS networks.
>>>
>>> Heh, how many people do we need to fix IBSS? :)
>>
>> Yeah, no kidding...I suspect that actual IBSS users are few, and a
>> substantial number of those are doing crazy things with it! :-)
> Yeah, we're doing crazy things like mesh networks of few hundred
> nodes... something that 11s isn't really suitable for. :-)

Anyone know if this applies for 32?

  Luis

Re: [PATCH] mac80211: Fix IBSS merge

[John W. Linville]

On Mon, Nov 02, 2009 at 06:20:41PM +0100, Felix Fietkau wrote:
> John W. Linville wrote:
> > On Mon, Nov 02, 2009 at 09:44:46AM +0100, Johannes Berg wrote:
> >> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
> >> > Currently, in IBSS mode, a single creator would go into
> >> > a loop trying to merge/scan. This happens because the IBSS timer is
> >> > rearmed on finishing a scan and the subsequent
> >> > timer invocation requests another scan immediately.
> >> > 
> >> > This patch fixes this issue by checking if we have just completed
> >> > a scan run trying to merge with other IBSS networks.
> >> 
> >> Heh, how many people do we need to fix IBSS? :)
> > 
> > Yeah, no kidding...I suspect that actual IBSS users are few, and a
> > substantial number of those are doing crazy things with it! :-)
> Yeah, we're doing crazy things like mesh networks of few hundred
> nodes... something that 11s isn't really suitable for. :-)

In fact, I had you in mind when I said that -- crazy doesn't mean
useless... :-)

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

Re: [PATCH] mac80211: Fix IBSS merge

[Felix Fietkau]

Luis R. Rodriguez wrote:
> On Mon, Nov 2, 2009 at 9:20 AM, Felix Fietkau <nbd@nbd.name> wrote:
>> John W. Linville wrote:
>>> On Mon, Nov 02, 2009 at 09:44:46AM +0100, Johannes Berg wrote:
>>>> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
>>>> > Currently, in IBSS mode, a single creator would go into
>>>> > a loop trying to merge/scan. This happens because the IBSS timer is
>>>> > rearmed on finishing a scan and the subsequent
>>>> > timer invocation requests another scan immediately.
>>>> >
>>>> > This patch fixes this issue by checking if we have just completed
>>>> > a scan run trying to merge with other IBSS networks.
>>>>
>>>> Heh, how many people do we need to fix IBSS? :)
>>>
>>> Yeah, no kidding...I suspect that actual IBSS users are few, and a
>>> substantial number of those are doing crazy things with it! :-)
>> Yeah, we're doing crazy things like mesh networks of few hundred
>> nodes... something that 11s isn't really suitable for. :-)
> 
> Anyone know if this applies for 32?
What exactly?

- Felix

Re: [PATCH] mac80211: Fix IBSS merge

[Luis R. Rodriguez]

On Mon, Nov 2, 2009 at 12:27 PM, Felix Fietkau <nbd@openwrt.org> wrote:
> Luis R. Rodriguez wrote:
>> On Mon, Nov 2, 2009 at 9:20 AM, Felix Fietkau <nbd@nbd.name> wrote:
>>> John W. Linville wrote:
>>>> On Mon, Nov 02, 2009 at 09:44:46AM +0100, Johannes Berg wrote:
>>>>> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
>>>>> > Currently, in IBSS mode, a single creator would go into
>>>>> > a loop trying to merge/scan. This happens because the IBSS timer is
>>>>> > rearmed on finishing a scan and the subsequent
>>>>> > timer invocation requests another scan immediately.
>>>>> >
>>>>> > This patch fixes this issue by checking if we have just completed
>>>>> > a scan run trying to merge with other IBSS networks.
>>>>>
>>>>> Heh, how many people do we need to fix IBSS? :)
>>>>
>>>> Yeah, no kidding...I suspect that actual IBSS users are few, and a
>>>> substantial number of those are doing crazy things with it! :-)
>>> Yeah, we're doing crazy things like mesh networks of few hundred
>>> nodes... something that 11s isn't really suitable for. :-)
>>
>> Anyone know if this applies for 32?
> What exactly?

The patch.

  Luis

Re: [PATCH] mac80211: Fix IBSS merge

[John W. Linville]

On Mon, Nov 02, 2009 at 12:36:31PM -0800, Luis R. Rodriguez wrote:
> On Mon, Nov 2, 2009 at 12:27 PM, Felix Fietkau <nbd@openwrt.org> wrote:
> > Luis R. Rodriguez wrote:
> >> On Mon, Nov 2, 2009 at 9:20 AM, Felix Fietkau <nbd@nbd.name> wrote:
> >>> John W. Linville wrote:
> >>>> On Mon, Nov 02, 2009 at 09:44:46AM +0100, Johannes Berg wrote:
> >>>>> On Mon, 2009-11-02 at 12:33 +0530, Sujith wrote:
> >>>>> > Currently, in IBSS mode, a single creator would go into
> >>>>> > a loop trying to merge/scan. This happens because the IBSS timer is
> >>>>> > rearmed on finishing a scan and the subsequent
> >>>>> > timer invocation requests another scan immediately.
> >>>>> >
> >>>>> > This patch fixes this issue by checking if we have just completed
> >>>>> > a scan run trying to merge with other IBSS networks.
> >>>>>
> >>>>> Heh, how many people do we need to fix IBSS? :)
> >>>>
> >>>> Yeah, no kidding...I suspect that actual IBSS users are few, and a
> >>>> substantial number of those are doing crazy things with it! :-)
> >>> Yeah, we're doing crazy things like mesh networks of few hundred
> >>> nodes... something that 11s isn't really suitable for. :-)
> >>
> >> Anyone know if this applies for 32?
> > What exactly?
> 
> The patch.

The patch applies and seems sane.  It seems like 2.6.32 would need it as well?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.