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Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode_store

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On 05/31/2017 05:29 AM, Jia-Ju Bai wrote:
> The driver may sleep under a spin lock, and the function call path is:
> b43legacy_attr_interfmode_store (acquire the lock by spin_lock_irqsave)
>    b43legacy_radio_set_interference_mitigation
>      b43legacy_radio_interference_mitigation_disable
>        b43legacy_calc_nrssi_slope
>          b43legacy_synth_pu_workaround
>            might_sleep and msleep --> may sleep
> 
> Fixing it may be complex, and a possible way is to remove
> spin_lock_irqsave and spin_lock_irqrestore in
> b43legacy_attr_interfmode_store, and the code has been protected by
> mutex_lock and mutex_unlock.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
> ---
>   drivers/net/wireless/broadcom/b43legacy/sysfs.c |    2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/b43legacy/sysfs.c b/drivers/net/wireless/broadcom/b43legacy/sysfs.c
> index 2a1da15..9ede143 100644
> --- a/drivers/net/wireless/broadcom/b43legacy/sysfs.c
> +++ b/drivers/net/wireless/broadcom/b43legacy/sysfs.c
> @@ -137,14 +137,12 @@ static ssize_t b43legacy_attr_interfmode_store(struct device *dev,
>   	}
>   
>   	mutex_lock(&wldev->wl->mutex);
> -	spin_lock_irqsave(&wldev->wl->irq_lock, flags);
>   
>   	err = b43legacy_radio_set_interference_mitigation(wldev, mode);
>   	if (err)
>   		b43legacyerr(wldev->wl, "Interference Mitigation not "
>   		       "supported by device\n");
>   	mmiowb();
> -	spin_unlock_irqrestore(&wldev->wl->irq_lock, flags);
>   	mutex_unlock(&wldev->wl->mutex);
>   
>   	return err ? err : count;
> 

Jia-Ju,

Did you actually observe the attempt to sleep under the spin lock, or did you 
discover this using some tool? In other words, have either of your patches been 
tested?

Larry

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[PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode_store Jia-Ju Bai <baijiaju1990@163.com> - 2017-05-31 12:30 +0200
  Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in  b43legacy_attr_interfmode_store Michael Büsch <m@bues.ch> - 2017-05-31 17:20 +0200
  Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in  b43legacy_attr_interfmode_store Larry Finger <Larry.Finger@lwfinger.net> - 2017-05-31 19:40 +0200
    Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode_store Jia-Ju Bai <baijiaju1990@163.com> - 2017-06-01 03:10 +0200
      Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode_store Kalle Valo <kvalo@codeaurora.org> - 2017-06-01 06:20 +0200
      Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in  b43legacy_attr_interfmode_store Jonathan Corbet <corbet@lwn.net> - 2017-06-01 18:20 +0200
        Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in  b43legacy_attr_interfmode_store Larry Finger <Larry.Finger@lwfinger.net> - 2017-06-01 19:50 +0200
        Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode_store Jia-Ju Bai <baijiaju1990@163.com> - 2017-06-02 03:20 +0200

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