linux-kernel - Re: [PATCH] Bluetooth: Re-order clearing suspend tasks

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Message-Id: <E430CF8E-218C-4C64-B963-57AE70CD11CB@holtmann.org>
Date:   Fri, 11 Sep 2020 09:06:04 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Cc:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Johan Hedberg <johan.hedberg@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH] Bluetooth: Re-order clearing suspend tasks

Hi Abhishek,

> Unregister_pm_notifier is a blocking call so suspend tasks should be
> cleared beforehand. Otherwise, the notifier will wait for completion
> before returning (and we encounter a 2s timeout on resume).
> 
> Fixes: 0e9952804ec9c8 (Bluetooth: Clear suspend tasks on unregister)
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> ---
> Should have caught that unregister_pm_notifier was blocking last time
> but when testing the earlier patch, I got unlucky and saw that the error
> message was never hit (the suspend timeout).
> 
> When re-testing this patch on the same device, I was able to reproduce
> the problem on an older build with the 0e9952804ec9c8 but not on a newer
> build with the same patch. Changing the order correctly fixes it
> everywhere. Confirmed this by adding debug logs in btusb_disconnect and
> hci_suspend_notifier to confirm what order things were getting called.
> 
> Sorry about the churn. Next I'm going try to do something about the palm
> shaped indentation on my forehead...
> 
> net/bluetooth/hci_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel