linux-kernel - Re: [PATCH v2] ath10k: skip ath10k_halt during suspend for driver state RESTARTING

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Message-ID: <87wnfbf47i.fsf@kernel.org>
Date:   Wed, 27 Apr 2022 09:08:49 +0300
From:   Kalle Valo <kvalo@...nel.org>
To:     Abhishek Kumar <kuabhs@...omium.org>
Cc:     quic_wgong@...cinc.com, briannorris@...omium.org,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        ath10k@...ts.infradead.org, netdev@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH v2] ath10k: skip ath10k_halt during suspend for driver state RESTARTING

Abhishek Kumar <kuabhs@...omium.org> writes:

> Double free crash is observed when FW recovery(caused by wmi
> timeout/crash) is followed by immediate suspend event. The FW recovery
> is triggered by ath10k_core_restart() which calls driver clean up via
> ath10k_halt(). When the suspend event occurs between the FW recovery,
> the restart worker thread is put into frozen state until suspend completes.
> The suspend event triggers ath10k_stop() which again triggers ath10k_halt()
> The double invocation of ath10k_halt() causes ath10k_htt_rx_free() to be
> called twice(Note: ath10k_htt_rx_alloc was not called by restart worker
> thread because of its frozen state), causing the crash.
>
> To fix this, during the suspend flow, skip call to ath10k_halt() in
> ath10k_stop() when the current driver state is ATH10K_STATE_RESTARTING.
> Also, for driver state ATH10K_STATE_RESTARTING, call
> ath10k_wait_for_suspend() in ath10k_stop(). This is because call to
> ath10k_wait_for_suspend() is skipped later in
> [ath10k_halt() > ath10k_core_stop()] for the driver state
> ATH10K_STATE_RESTARTING.
>
> The frozen restart worker thread will be cancelled during resume when the
> device comes out of suspend.
>
> Below is the crash stack for reference:
>
> [  428.469167] ------------[ cut here ]------------
> [  428.469180] kernel BUG at mm/slub.c:4150!
> [  428.469193] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
> [  428.469219] Workqueue: events_unbound async_run_entry_fn
> [  428.469230] RIP: 0010:kfree+0x319/0x31b
> [  428.469241] RSP: 0018:ffffa1fac015fc30 EFLAGS: 00010246
> [  428.469247] RAX: ffffedb10419d108 RBX: ffff8c05262b0000
> [  428.469252] RDX: ffff8c04a8c07000 RSI: 0000000000000000
> [  428.469256] RBP: ffffa1fac015fc78 R08: 0000000000000000
> [  428.469276] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  428.469285] Call Trace:
> [  428.469295]  ? dma_free_attrs+0x5f/0x7d
> [  428.469320]  ath10k_core_stop+0x5b/0x6f
> [  428.469336]  ath10k_halt+0x126/0x177
> [  428.469352]  ath10k_stop+0x41/0x7e
> [  428.469387]  drv_stop+0x88/0x10e
> [  428.469410]  __ieee80211_suspend+0x297/0x411
> [  428.469441]  rdev_suspend+0x6e/0xd0
> [  428.469462]  wiphy_suspend+0xb1/0x105
> [  428.469483]  ? name_show+0x2d/0x2d
> [  428.469490]  dpm_run_callback+0x8c/0x126
> [  428.469511]  ? name_show+0x2d/0x2d
> [  428.469517]  __device_suspend+0x2e7/0x41b
> [  428.469523]  async_suspend+0x1f/0x93
> [  428.469529]  async_run_entry_fn+0x3d/0xd1
> [  428.469535]  process_one_work+0x1b1/0x329
> [  428.469541]  worker_thread+0x213/0x372
> [  428.469547]  kthread+0x150/0x15f
> [  428.469552]  ? pr_cont_work+0x58/0x58
> [  428.469558]  ? kthread_blkcg+0x31/0x31
>
> Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00288-QCARMSWPZ-1
> Co-developed-by: Wen Gong <quic_wgong@...cinc.com>
> Signed-off-by: Wen Gong <quic_wgong@...cinc.com>
> Signed-off-by: Abhishek Kumar <kuabhs@...omium.org>
> ---
>
> Changes in v2:
> - Fixed typo, replaced ath11k by ath10k in the comments.
> - Adjusted the position of my S-O-B tag.
> - Added the Tested-on tag.
>
>  drivers/net/wireless/ath/ath10k/mac.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
> index d804e19a742a..e9c1f11fef0a 100644
> --- a/drivers/net/wireless/ath/ath10k/mac.c
> +++ b/drivers/net/wireless/ath/ath10k/mac.c
> @@ -5345,8 +5345,22 @@ static void ath10k_stop(struct ieee80211_hw *hw)
>  
>  	mutex_lock(&ar->conf_mutex);
>  	if (ar->state != ATH10K_STATE_OFF) {
> -		if (!ar->hw_rfkill_on)
> -			ath10k_halt(ar);
> +		if (!ar->hw_rfkill_on) {
> +			/* If the current driver state is RESTARTING but not yet
> +			 * fully RESTARTED because of incoming suspend event,
> +			 * then ath10k_halt is already called via
> +			 * ath10k_core_restart and should not be called here.
> +			 */
> +			if (ar->state != ATH10K_STATE_RESTARTING)
> +				ath10k_halt(ar);
> +			else
> +				/* Suspending here, because when in RESTARTING
> +				 * state, ath10k_core_stop skips
> +				 * ath10k_wait_for_suspend.
> +				 */
> +				ath10k_wait_for_suspend(ar,
> +							WMI_PDEV_SUSPEND_AND_DISABLE_INTR);
> +		}

I'm nitpicking but I prefer to use parenthesis with function names, so I
changed the comments. Also there was one ath10k-check warning:

drivers/net/wireless/ath/ath10k/mac.c:5360: line length of 91 exceeds 90 columns

In the pending branch I changed it to:

			if (ar->state != ATH10K_STATE_RESTARTING) {
				ath10k_halt(ar);
			} else {
				/* Suspending here, because when in RESTARTING
				 * state, ath10k_core_stop() skips
				 * ath10k_wait_for_suspend().
				 */
				opt = WMI_PDEV_SUSPEND_AND_DISABLE_INTR;
				ath10k_wait_for_suspend(ar, opt);
			}

Not really pretty but I prefer to keep ath10k warning free.

-- 
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