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Subject: Re: [PATCH] Bluetooth: hci_bcm: fix double-free irq on removal
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20190226184636.02694ee7@aktux>
Date:   Wed, 27 Feb 2019 08:43:21 +0100
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        "open list:BLUETOOTH DRIVERS" <linux-bluetooth@vger.kernel.org>,
        linux-kernel@vger.kernel.org, josua.mayer@jm0.eu
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References: <20190225195010.32277-1-andreas@kemnade.info>
 <EB7BF015-9874-47E5-B736-16DF4EA342A7@holtmann.org>
 <20190226184636.02694ee7@aktux>
To:     Andreas Kemnade <andreas@kemnade.info>
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Hi Andreas,

>>> after rmmod hci_uart a warning about doubly freed
>>> interrupts appears, so do it only once. Instead disable it.
>>> It is already implicitely freed by the devm framework.
>>> 
>>> [  230.782948] ------------[ cut here ]------------
>>> [  230.787708] WARNING: CPU: 0 PID: 2715 at kernel/irq/devres.c:146 devm_free_irq+0x59/0x60
>>> [  230.798345] Modules linked in: usb_f_ecm u_ether libcomposite spidev hidp rfcomm hci_uart(-) btbcm bluetooth ecdh_generic brcmfmac brcmutil cfg80211 rfkill evdev sun8i_codec_analog sun8i_adda_pr_regmap snd_soc_core snd_pcm_dmaengine pwrseq_simple snd_pcm snd_timer snd soundcore hih6130 cpufreq_dt uio_pdrv_genirq gpio_keys uio thermal_sys
>>> [  230.828282] CPU: 0 PID: 2715 Comm: rmmod Not tainted 5.0.0-rc8+ #14
>>> [  230.834540] Hardware name: Allwinner sun8i Family
>>> [  230.839266] [<c010d4dd>] (unwind_backtrace) from [<c010a189>] (show_stack+0x11/0x14)
>>> [  230.847014] [<c010a189>] (show_stack) from [<c085867b>] (dump_stack+0x67/0x74)
>>> [  230.854240] [<c085867b>] (dump_stack) from [<c011afd1>] (__warn+0xb9/0xcc)
>>> [  230.861115] [<c011afd1>] (__warn) from [<c011b0ab>] (warn_slowpath_null+0x2f/0x34)
>>> [  230.868681] [<c011b0ab>] (warn_slowpath_null) from [<c0163889>] (devm_free_irq+0x59/0x60)
>>> [  230.876881] [<c0163889>] (devm_free_irq) from [<bfb101b1>] (bcm_close+0x35/0xa8 [hci_uart])
>>> [  230.885264] [<bfb101b1>] (bcm_close [hci_uart]) from [<bfb0cd3f>] (hci_uart_unregister_device+0x33/0x3c [hci_uart])
>>> [  230.895708] [<bfb0cd3f>] (hci_uart_unregister_device [hci_uart]) from [<bfb0f9b7>] (bcm_serdev_remove+0xf/0x10 [hci_uart])
>>> [  230.906755] [<bfb0f9b7>] (bcm_serdev_remove [hci_uart]) from [<c057896f>] (serdev_drv_remove+0x13/0x20)
>>> [  230.916150] [<c057896f>] (serdev_drv_remove) from [<c05c1597>] (device_release_driver_internal+0xf7/0x158)
>>> [  230.925799] [<c05c1597>] (device_release_driver_internal) from [<c05c1651>] (driver_detach+0x49/0x78)
>>> [  230.935013] [<c05c1651>] (driver_detach) from [<c05c08f1>] (bus_remove_driver+0x31/0x70)
>>> [  230.943108] [<c05c08f1>] (bus_remove_driver) from [<bfb10357>] (bcm_deinit+0x1b/0xcc4 [hci_uart])
>>> [  230.951994] [<bfb10357>] (bcm_deinit [hci_uart]) from [<bfb102bb>] (hci_uart_exit+0x1b/0x34 [hci_uart])
>>> [  230.961389] [<bfb102bb>] (hci_uart_exit [hci_uart]) from [<c0185f09>] (sys_delete_module+0x135/0x178)
>>> [  230.970603] [<c0185f09>] (sys_delete_module) from [<c0101001>] (ret_fast_syscall+0x1/0x62)
>>> [  230.978855] Exception stack(0xd66b7fa8 to 0xd66b7ff0)
>>> [  230.983906] 7fa0:                   00c3dd00 00000000 00c3dd3c 00000800 88297c00 88297c00
>>> [  230.992078] 7fc0: 00c3dd00 00000000 bef05e82 00000081 bef05b88 00000001 bef05d7c 00000000
>>> [  231.000245] 7fe0: 0045bf6c bef05b24 00441303 b6edab26
>>> [  231.005332] ---[ end trace dc4caa46c945c790 ]---
>>> [  231.009946] ------------[ cut here ]------------
>>> [  231.014567] WARNING: CPU: 0 PID: 2715 at kernel/irq/manage.c:1600 __free_irq+0x83/0x20c
>>> [  231.025070] Trying to free already-free IRQ 92
>>> [  231.029505] Modules linked in: usb_f_ecm u_ether libcomposite spidev hidp rfcomm hci_uart(-) btbcm bluetooth ecdh_generic brcmfmac brcmutil cfg80211 rfkill evdev sun8i_codec_analog sun8i_adda_pr_regmap snd_soc_core snd_pcm_dmaengine pwrseq_simple snd_pcm snd_timer snd soundcore hih6130 cpufreq_dt uio_pdrv_genirq gpio_keys uio thermal_sys
>>> [  231.059389] CPU: 0 PID: 2715 Comm: rmmod Tainted: G        W         5.0.0-rc8+ #14
>>> [  231.067032] Hardware name: Allwinner sun8i Family
>>> [  231.071740] [<c010d4dd>] (unwind_backtrace) from [<c010a189>] (show_stack+0x11/0x14)
>>> [  231.079481] [<c010a189>] (show_stack) from [<c085867b>] (dump_stack+0x67/0x74)
>>> [  231.086701] [<c085867b>] (dump_stack) from [<c011afd1>] (__warn+0xb9/0xcc)
>>> [  231.093574] [<c011afd1>] (__warn) from [<c011b017>] (warn_slowpath_fmt+0x33/0x48)
>>> [  231.101054] [<c011b017>] (warn_slowpath_fmt) from [<c0160a03>] (__free_irq+0x83/0x20c)
>>> [  231.108966] [<c0160a03>] (__free_irq) from [<c0160be7>] (free_irq+0x27/0x5c)
>>> [  231.116012] [<c0160be7>] (free_irq) from [<c016386f>] (devm_free_irq+0x3f/0x60)
>>> [  231.123326] [<c016386f>] (devm_free_irq) from [<bfb101b1>] (bcm_close+0x35/0xa8 [hci_uart])
>>> [  231.131690] [<bfb101b1>] (bcm_close [hci_uart]) from [<bfb0cd3f>] (hci_uart_unregister_device+0x33/0x3c [hci_uart])
>>> [  231.142133] [<bfb0cd3f>] (hci_uart_unregister_device [hci_uart]) from [<bfb0f9b7>] (bcm_serdev_remove+0xf/0x10 [hci_uart])
>>> [  231.153174] [<bfb0f9b7>] (bcm_serdev_remove [hci_uart]) from [<c057896f>] (serdev_drv_remove+0x13/0x20)
>>> [  231.162562] [<c057896f>] (serdev_drv_remove) from [<c05c1597>] (device_release_driver_internal+0xf7/0x158)
>>> [  231.172209] [<c05c1597>] (device_release_driver_internal) from [<c05c1651>] (driver_detach+0x49/0x78)
>>> [  231.181422] [<c05c1651>] (driver_detach) from [<c05c08f1>] (bus_remove_driver+0x31/0x70)
>>> [  231.189517] [<c05c08f1>] (bus_remove_driver) from [<bfb10357>] (bcm_deinit+0x1b/0xcc4 [hci_uart])
>>> [  231.198399] [<bfb10357>] (bcm_deinit [hci_uart]) from [<bfb102bb>] (hci_uart_exit+0x1b/0x34 [hci_uart])
>>> [  231.207793] [<bfb102bb>] (hci_uart_exit [hci_uart]) from [<c0185f09>] (sys_delete_module+0x135/0x178)
>>> [  231.217005] [<c0185f09>] (sys_delete_module) from [<c0101001>] (ret_fast_syscall+0x1/0x62)
>>> [  231.225256] Exception stack(0xd66b7fa8 to 0xd66b7ff0)
>>> [  231.230305] 7fa0:                   00c3dd00 00000000 00c3dd3c 00000800 88297c00 88297c00
>>> [  231.238476] 7fc0: 00c3dd00 00000000 bef05e82 00000081 bef05b88 00000001 bef05d7c 00000000
>>> [  231.246644] 7fe0: 0045bf6c bef05b24 00441303 b6edab26
>>> [  231.251688] ---[ end trace dc4caa46c945c791 ]---
>>> 
>>> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
>>> ---
>>> drivers/bluetooth/hci_bcm.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>> 
>>> diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
>>> index ddbe518c3e5b..97a8ba607d0c 100644
>>> --- a/drivers/bluetooth/hci_bcm.c
>>> +++ b/drivers/bluetooth/hci_bcm.c
>>> @@ -488,7 +488,7 @@ static int bcm_close(struct hci_uart *hu)
>>> 
>>> 	if (bdev) {
>>> 		if (IS_ENABLED(CONFIG_PM) && bdev->irq > 0) {
>>> -			devm_free_irq(bdev->dev, bdev->irq, bdev);
>>> +			disable_irq(bdev->irq);
>>> 			device_init_wakeup(bdev->dev, false);
>>> 			pm_runtime_disable(bdev->dev);
>>> 		}  
>> 
>> this fix is too simplistic I think. If we don’t free it here, then subsequent calls to btattach will leave an IRQ around. Or driver unbind/rebind action might trigger this as well.
>> 
> hmm, driver bind/unbind should be no problem, devm will clean up. a
> close()+setup() without unbind/removal in between could be a problem.
> But then we can simply solve the problem by not use a devm-managed irq
> here. So setup()+close() will look symmetrical.

we might really better do that since the hci_ldisc is too convoluted and maybe not a good fit for devm_ variants. At some point this all needs to migrate to bauart.c and bt3wire.c new drivers.

Regards

Marcel