Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[Adrian Chadd]

fwiw, I'm facing the same kinds of cleanup problems with my port of
(oct 2015) ath10k to freebsd.

The oct 2015 ath10k tree doesn't have the firmware per-txq/tid/peer
feedback stuff in it, so this hasn't yet bitten me, but there rest of
the races have - mostly surrounding handling pending TX frames when a
VAP is deleted (vdev/interface in ath10k/mac80211 language) and if any
TX frames were stuck. Stuck TX frames happens more often than I'd like
because of how earlier firmware required peer entries to first appear
in the hardware.

Maybe we need some kind of lifecycle checkpoint for things like peer
addition/removal (for the txq issues ben had before) and the ability
to ask the firmware to stop/flush HTT TX and re-start it. That way we
can cleanly add/remove interfaces at any point without worrying about
any dangling frames in the transmit queue waiting for completion.



-adrian

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Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[Ben Greear]

On 12/05/2016 05:52 AM, Johannes Berg wrote:

On Mon, 2016-12-05 at 09:13 +0100, Michal Kazior wrote:

On 2 December 2016 at 03:29,   wrote:


From: Ben Greear 

This appears to fix a problem where ath10k firmware would crash,
mac80211 would start re-adding interfaces to the driver, but the
iterate-active-interfaces logic would then try to use the half-
built
interfaces.  With a bit of extra debug to catch the problem, the
ath10k crash looks like this:

ath10k_pci :05:00.0: Initializing arvif: 8801ce97e320 on
vif: 8801ce97e1d8

[the print that happens after arvif->ar is assigned is not shown,
so code did not make it that far before
  the tx-beacon-nowait method was called]

tx-beacon-nowait:  arvif: 8801ce97e320  ar:   (null)

[...]



Signed-off-by: Ben Greear 
---
  net/mac80211/util.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 863f2c1..abe1f64 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -705,7 +705,7 @@ static void __iterate_interfaces(struct
ieee80211_local *local,
 break;
 }
 if (!(iter_flags & IEEE80211_IFACE_ITER_RESUME_ALL)
&&
-   active_only && !(sdata->flags &
IEEE80211_SDATA_IN_DRIVER))
+   (active_only && (local->in_reconfig || !(sdata-

flags & IEEE80211_SDATA_IN_DRIVER

 continue;


Doesn't this effectivelly prevent you from iterating over interfaces
completely during reconfig? As you bring up interfaces you might
need/want to iterate over others to re-adjust your own state.


Agree, that doesn't really make sense.


I'd argue there should be another flag, IEEE80211_SDATA_RESUMING,
used with sdata->flags for resuming so that once it is re-added to
the driver it can be cleared (and therefore properly iterated over).


That would make some sense, or perhaps the sdata_in_driver should be
cleared (and remembered elsewhere) at some point during the restart.


I think clearing sdata-in-driver would fix the ath10k problem, at least,
but I was afraid it would break something else in mac80211 or maybe in
other thick firmware drivers.

One way or another, we cannot be iterating over interfaces while
the interfaces are at the same time being (re)added.

Maybe mac80211 should explicitly remove all interfaces from the driver
during crash recovery?  And the behaviour needs to be clearly documented 
somewhere
easy to find so that we can think about and program to the correct API
behaviour.

Thanks,
Bne




johannes

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--
Ben Greear 
Candela Technologies Inc  http://www.candelatech.com

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Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[Ben Greear]

On 12/05/2016 07:00 AM, Johannes Berg wrote:

On Mon, 2016-12-05 at 06:57 -0800, Ben Greear wrote:


I think clearing sdata-in-driver would fix the ath10k problem, at
least, but I was afraid it would break something else in mac80211 or
maybe in other thick firmware drivers.


It's pretty much an internal thing - not sure what it'd break. OTOH,
some drivers might actually assume that iterating finds them all, if
they never clear the data even across a restart?


One way or another, we cannot be iterating over interfaces while
the interfaces are at the same time being (re)added.


Well, we obviously *can* be, and we do in fact do that - it's just that
ath10k specifically has issues with the data it's putting there, no?


It causes races that appear to be very difficult to resolve in the
driver alone.  On normal bringup of an interface, the sdata-in-driver
flag is only set at the bottom of the add-interface.  In case of re-config,
the flag is already set, and never cleared, so behaviour is different
w/regard to the iterate.




Maybe mac80211 should explicitly remove all interfaces from the
driver during crash recovery?


I don't think that'll work. Removing them would interact with the
firmware, which is dead, etc. That'd just cause trouble.


That issue already causes trouble and is dealt with in ath10k, I think,
but clearing the flag in mac80211 would probably be enough to fix the
iterate logic.


And the behaviour needs to be clearly documented somewhere
easy to find so that we can think about and program to the correct
API behaviour.


We assume that the driver resets all its internal state - this whole
interface iteration is a corner case we hadn't considered, I suppose.


Yeah, tricky beastie.  I think the txq issue is also part of this since there
are references up in mac80211 and also down in ath10k.  Part of my hack
to clean up that crash might be resolved by mac80211 doing better cleanup
API when firmware crashes.

Thanks,
Ben



johannes



--
Ben Greear 
Candela Technologies Inc  http://www.candelatech.com

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Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[Johannes Berg]

On Mon, 2016-12-05 at 06:57 -0800, Ben Greear wrote:

> I think clearing sdata-in-driver would fix the ath10k problem, at
> least, but I was afraid it would break something else in mac80211 or
> maybe in other thick firmware drivers.

It's pretty much an internal thing - not sure what it'd break. OTOH,
some drivers might actually assume that iterating finds them all, if
they never clear the data even across a restart?

> One way or another, we cannot be iterating over interfaces while
> the interfaces are at the same time being (re)added.

Well, we obviously *can* be, and we do in fact do that - it's just that
ath10k specifically has issues with the data it's putting there, no?

> Maybe mac80211 should explicitly remove all interfaces from the
> driver during crash recovery?  

I don't think that'll work. Removing them would interact with the
firmware, which is dead, etc. That'd just cause trouble.

> And the behaviour needs to be clearly documented somewhere
> easy to find so that we can think about and program to the correct
> API behaviour.

We assume that the driver resets all its internal state - this whole
interface iteration is a corner case we hadn't considered, I suppose.

johannes

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Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[Johannes Berg]

On Mon, 2016-12-05 at 09:13 +0100, Michal Kazior wrote:
> On 2 December 2016 at 03:29,   wrote:
> > 
> > From: Ben Greear 
> > 
> > This appears to fix a problem where ath10k firmware would crash,
> > mac80211 would start re-adding interfaces to the driver, but the
> > iterate-active-interfaces logic would then try to use the half-
> > built
> > interfaces.  With a bit of extra debug to catch the problem, the
> > ath10k crash looks like this:
> > 
> > ath10k_pci :05:00.0: Initializing arvif: 8801ce97e320 on
> > vif: 8801ce97e1d8
> > 
> > [the print that happens after arvif->ar is assigned is not shown,
> > so code did not make it that far before
> >  the tx-beacon-nowait method was called]
> > 
> > tx-beacon-nowait:  arvif: 8801ce97e320  ar:   (null)
> [...]
> > 
> > 
> > Signed-off-by: Ben Greear 
> > ---
> >  net/mac80211/util.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> > index 863f2c1..abe1f64 100644
> > --- a/net/mac80211/util.c
> > +++ b/net/mac80211/util.c
> > @@ -705,7 +705,7 @@ static void __iterate_interfaces(struct
> > ieee80211_local *local,
> > break;
> > }
> > if (!(iter_flags & IEEE80211_IFACE_ITER_RESUME_ALL)
> > &&
> > -   active_only && !(sdata->flags &
> > IEEE80211_SDATA_IN_DRIVER))
> > +   (active_only && (local->in_reconfig || !(sdata-
> > >flags & IEEE80211_SDATA_IN_DRIVER
> > continue;
> 
> Doesn't this effectivelly prevent you from iterating over interfaces
> completely during reconfig? As you bring up interfaces you might
> need/want to iterate over others to re-adjust your own state.

Agree, that doesn't really make sense.

> I'd argue there should be another flag, IEEE80211_SDATA_RESUMING,
> used with sdata->flags for resuming so that once it is re-added to
> the driver it can be cleared (and therefore properly iterated over).

That would make some sense, or perhaps the sdata_in_driver should be
cleared (and remembered elsewhere) at some point during the restart.

johannes

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Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[Michal Kazior]

On 2 December 2016 at 03:29,   wrote:
> From: Ben Greear 
>
> This appears to fix a problem where ath10k firmware would crash,
> mac80211 would start re-adding interfaces to the driver, but the
> iterate-active-interfaces logic would then try to use the half-built
> interfaces.  With a bit of extra debug to catch the problem, the
> ath10k crash looks like this:
>
> ath10k_pci :05:00.0: Initializing arvif: 8801ce97e320 on vif: 
> 8801ce97e1d8
>
> [the print that happens after arvif->ar is assigned is not shown, so code did 
> not make it that far before
>  the tx-beacon-nowait method was called]
>
> tx-beacon-nowait:  arvif: 8801ce97e320  ar:   (null)
[...]
>
> Signed-off-by: Ben Greear 
> ---
>  net/mac80211/util.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> index 863f2c1..abe1f64 100644
> --- a/net/mac80211/util.c
> +++ b/net/mac80211/util.c
> @@ -705,7 +705,7 @@ static void __iterate_interfaces(struct ieee80211_local 
> *local,
> break;
> }
> if (!(iter_flags & IEEE80211_IFACE_ITER_RESUME_ALL) &&
> -   active_only && !(sdata->flags & 
> IEEE80211_SDATA_IN_DRIVER))
> +   (active_only && (local->in_reconfig || !(sdata->flags & 
> IEEE80211_SDATA_IN_DRIVER
> continue;

Doesn't this effectivelly prevent you from iterating over interfaces
completely during reconfig? As you bring up interfaces you might
need/want to iterate over others to re-adjust your own state.

I'd argue there should be another flag, IEEE80211_SDATA_RESUMING, used
with sdata->flags for resuming so that once it is re-added to the
driver it can be cleared (and therefore properly iterated over).


Michał

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[PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[greearb]

From: Ben Greear 

This appears to fix a problem where ath10k firmware would crash,
mac80211 would start re-adding interfaces to the driver, but the
iterate-active-interfaces logic would then try to use the half-built
interfaces.  With a bit of extra debug to catch the problem, the
ath10k crash looks like this:

ath10k_pci :05:00.0: Initializing arvif: 8801ce97e320 on vif: 
8801ce97e1d8

[the print that happens after arvif->ar is assigned is not shown, so code did 
not make it that far before
 the tx-beacon-nowait method was called]

tx-beacon-nowait:  arvif: 8801ce97e320  ar:   (null)
arvif->magic: 0x87560001
[ cut here ]
kernel BUG at 
/home/greearb/git/linux-4.7.dev.y/drivers/net/wireless/ath/ath10k/wmi.c:1781!
invalid opcode:  [#1] PREEMPT SMP KASAN
Modules linked in: nf_conntrack_netlink nf_conntrack nfnetlink nf_defrag_ipv4 
bridge carl9170 mac80211_hwsim ath10k_pci ath10k_core ath5k ath9k ath9k_common 
ath9k_hw ath mac80211 cfg80211 8021q garp mrp stp llc bnep bluetooth fuse 
macvlan pktgen rpcsec_gss_krb5 nfsv4 nfs fscache snd_hda_codec_hdmi coretemp 
hwmon intel_rapl x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_realtek 
snd_hda_codec_generic kvm iTCO_wdt irqbypass iTCO_vendor_support joydev 
snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device 
pcspkr snd_pcm snd_timer shpchp snd i2c_i801 lpc_ich soundcore tpm_tis tpm nfsd 
auth_rpcgss nfs_acl lockd grace sunrpc i915 serio_raw i2c_algo_bit 
drm_kms_helper ata_generic e1000e pata_acpi drm ptp pps_core i2c_core fjes 
video ipv6 [last unloaded: nf_conntrack]
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.7.10+ #15
Hardware name: To be filled by O.E.M. To be filled by O.E.M./ChiefRiver, BIOS 
4.6.5 06/07/2013
task: 8801d4f2 ti: 8801d4f28000 task.ti: 8801d4f28000
RIP: 0010:[]  [] 
ath10k_wmi_tx_beacons_iter+0x28b/0x290 [ath10k_core]
RSP: 0018:8801d6447a98  EFLAGS: 00010293
RAX: 0018 RBX: 8801ce97e1d8 RCX: 
RDX: 0018 RSI: 0003 RDI: ed003ac88f49
RBP: 8801d6447af0 R08: 0003 R09: 
R10: 0001 R11: 0001 R12: 
R13: 8801ce97e320 R14: 8801ce97e378 R15: 8801ce97ca40
FS:  () GS:8801d644() knlGS:
CS:  0010 DS:  ES:  CR0: 80050033
CR2: 7eff191ef1ab CR3: 0260a000 CR4: 001406e0
Stack:
 11003ac88f59 41b58ab3 a0f4d52a 8801d4f2
 0246 0002 8801ce97e1d8 8801bd5d39b8
 0002 0001 8801ce97ca40 8801d6447b48
Call Trace:
 
 [] __iterate_interfaces+0xfc/0x1d0 [mac80211]
 [] ? ath10k_wmi_cmd_send_nowait+0x260/0x260 [ath10k_core]
 [] ? ath10k_wmi_cmd_send_nowait+0x260/0x260 [ath10k_core]
 [] ieee80211_iterate_active_interfaces_atomic+0x67/0x100 
[mac80211]
 [] ? ieee80211_handle_reconfig_failure+0x140/0x140 [mac80211]
 [] ? ath10k_tpc_config_disp_tables+0x620/0x620 [ath10k_core]
 [] ath10k_wmi_op_ep_tx_credits+0x2b/0x50 [ath10k_core]
 [] ath10k_htc_rx_completion_handler+0x422/0x5c0 [ath10k_core]
 [] ath10k_pci_process_rx_cb+0x37e/0x430 [ath10k_pci]
 [] ? ath10k_htc_build_tx_ctrl_skb+0xc0/0xc0 [ath10k_core]
 [] ? ath10k_pci_rx_post_pipe+0x550/0x550 [ath10k_pci]
 [] ? debug_lockdep_rcu_enabled+0x35/0x40
 [] ? mark_held_locks+0x23/0xc0
 [] ? __local_bh_enable_ip+0x6a/0xd0
 [] ? trace_hardirqs_on_caller+0x18b/0x290
 [] ? trace_hardirqs_on+0xd/0x10
 [] ? __local_bh_enable_ip+0x6a/0xd0
 [] ? _raw_spin_unlock_bh+0x30/0x40
 [] ? ath10k_ce_per_engine_service+0xee/0x100 [ath10k_pci]
 [] ath10k_pci_htt_htc_rx_cb+0x29/0x30 [ath10k_pci]
 [] ath10k_ce_per_engine_service+0xa6/0x100 [ath10k_pci]
 [] ath10k_ce_per_engine_service_any+0xd6/0xf0 [ath10k_pci]
 [] ? ath10k_pci_enable_legacy_irq+0xe0/0xe0 [ath10k_pci]
 [] ath10k_pci_tasklet+0x5f/0xb0 [ath10k_pci]
 [] tasklet_action+0x245/0x2b0
 [] __do_softirq+0x181/0x595
 [] irq_exit+0xbc/0xc0
 [] do_IRQ+0x7c/0x150
 [] common_interrupt+0x8c/0x8c
 
 [] ? trace_hardirqs_on_caller+0x18b/0x290
 [] ? cpuidle_enter_state+0x1ae/0x4b0
 [] ? cpuidle_enter_state+0x1a7/0x4b0
 [] cpuidle_enter+0x12/0x20
 [] call_cpuidle+0x4e/0x90
 [] cpu_startup_entry+0x3f7/0x540
 [] ? default_idle_call+0x50/0x50
 [] ? clockevents_config_and_register+0x5f/0x70
 [] ? setup_APIC_timer+0xfa/0x110
 [] start_secondary+0x253/0x2b0
 [] ? set_cpu_sibling_map+0x920/0x920
Code: 4d 49 e0 8b b3 48 01 00 00 48 c7 c7 a0 ee f3 a0 e8 d9 c2 3f e0 49 81 fd 
3f 1f 00 00 76 0f 49 81 fc 3f 1f 00 00 0f 87 c0 fd ff ff <0f> 0b 0f 0b 90 55 48 
89 e5 41 57 41 56 48 8d 85 58 ff ff ff 41
RIP  [] ath10k_wmi_tx_beacons_iter+0x28b/0x290 [ath10k_core]
 RSP 
---[ end trace 6588464714e5163a ]---

Signed-off-by: Ben Greear 
---
 net/mac80211/util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c