Re: [PATCH] usb: dwc2: Fix error path in gadget registration

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Hi Marek,

On 7/15/2020 12:42 PM, Marek Szyprowski wrote:
> Hi Minas,
> 
> On 14.07.2020 14:32, Minas Harutyunyan wrote:
>> On 7/14/2020 12:48 PM, Marek Szyprowski wrote:
>>> When gadget registration fails, one should not call usb_del_gadget_udc().
>>> Ensure this by setting gadget->udc to NULL. Also in case of a failure
>> I was able to reproduce issue. I'm Ok with this fix.
>>
>>> there is no need to disable low-level hardware, so return immiedetly
>>> instead of jumping to error_init label.
>>>
>> Why do you think that disable low-level hardware not required which was
>> enabled before? Also for some platforms required to call
>> regulator_disable() which was enabled earlier in probe function.
>> So, I suggest to keep jump to error_init label.
> 
> If I keep the jump to error_init label, then there is unbalanced call to
> dwc2_lowlevel_hw_disable(). usb_add_gadget_udc() can fail in 2 places:
> on gadget->bind() or during udc_start(). In the first case, the HW was
> not yet enabled, so there is no need to disable it. In the latter one,
> the error might be returned only from the dwc2_lowlevel_hw_enable(), so
> again there is no need to call dwc2_lowlevel_hw_disable().
> 
> If I keep the "goto error_init;" line, I get the following errors:
> 
> dwc2 12480000.hsotg: dwc2_check_params: Invalid parameter besl=1
> dwc2 12480000.hsotg: dwc2_check_params: Invalid parameter
> g_np_tx_fifo_size=1024
> dwc2 12480000.hsotg: EPs: 16, dedicated fifos, 7808 entries in SPRAM
> Mass Storage Function, version: 2009/09/11
> LUN: removable file: (no medium)
> no file given for LUN0
> g_mass_storage 12480000.hsotg: failed to start g_mass_storage: -22
> ------------[ cut here ]------------
> WARNING: CPU: 3 PID: 49 at drivers/clk/clk.c:958
> clk_core_disable+0x1e4/0x314
> usb_device already disabled
> Modules linked in:
> CPU: 3 PID: 49 Comm: kworker/3:1 Not tainted
> 5.8.0-rc5-next-20200714-00003-g105f360ba595-dirty #8758
> Hardware name: Samsung Exynos (Flattened Device Tree)
> Workqueue: events deferred_probe_work_func
> [<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
> [<c010d250>] (show_stack) from [<c051b8fc>] (dump_stack+0xbc/0xe8)
> [<c051b8fc>] (dump_stack) from [<c0126ed8>] (__warn+0xf0/0x108)
> [<c0126ed8>] (__warn) from [<c0126f64>] (warn_slowpath_fmt+0x74/0xb8)
> [<c0126f64>] (warn_slowpath_fmt) from [<c056c338>]
> (clk_core_disable+0x1e4/0x314)
> [<c056c338>] (clk_core_disable) from [<c056c480>]
> (clk_core_disable_lock+0x18/0x24)
> [<c056c480>] (clk_core_disable_lock) from [<c073f9d4>]
> (__dwc2_lowlevel_hw_disable+0x3c/0xa0)
> [<c073f9d4>] (__dwc2_lowlevel_hw_disable) from [<c0740188>]
> (dwc2_driver_probe+0x2d4/0x6ac)
> [<c0740188>] (dwc2_driver_probe) from [<c0653640>]
> (platform_drv_probe+0x6c/0xa4)
> [<c0653640>] (platform_drv_probe) from [<c0650bdc>]
> (really_probe+0x200/0x4fc)
> [<c0650bdc>] (really_probe) from [<c0651040>]
> (driver_probe_device+0x78/0x1fc)
> [<c0651040>] (driver_probe_device) from [<c064ea78>]
> (bus_for_each_drv+0x74/0xb8)
> [<c064ea78>] (bus_for_each_drv) from [<c065093c>]
> (__device_attach+0xd4/0x16c)
> [<c065093c>] (__device_attach) from [<c064fa3c>]
> (bus_probe_device+0x88/0x90)
> [<c064fa3c>] (bus_probe_device) from [<c064ff54>]
> (deferred_probe_work_func+0x3c/0xd0)
> [<c064ff54>] (deferred_probe_work_func) from [<c0148a5c>]
> (process_one_work+0x234/0x7dc)
> [<c0148a5c>] (process_one_work) from [<c0149048>] (worker_thread+0x44/0x51c)
> [<c0149048>] (worker_thread) from [<c015039c>] (kthread+0x158/0x1a0)
> [<c015039c>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
> Exception stack(0xee923fb0 to 0xee923ff8)
> ...
> irq event stamp: 36966
> hardirqs last  enabled at (36965): [<c02b92d8>] kfree+0x1a4/0x3f0
> hardirqs last disabled at (36966): [<c0569edc>] clk_enable_lock+0x14/0x134
> softirqs last  enabled at (36814): [<c010174c>] __do_softirq+0x50c/0x608
> softirqs last disabled at (36803): [<c0130218>] irq_exit+0x168/0x16c
> ---[ end trace f55f4b28f3080c12 ]---
> ------------[ cut here ]------------
> WARNING: CPU: 3 PID: 49 at drivers/clk/clk.c:817
> clk_core_unprepare+0x33c/0x470
> usb_device already unprepared
> Modules linked in:
> CPU: 3 PID: 49 Comm: kworker/3:1 Tainted: G        W
> 5.8.0-rc5-next-20200714-00003-g105f360ba595-dirty #8758
> Hardware name: Samsung Exynos (Flattened Device Tree)
> Workqueue: events deferred_probe_work_func
> [<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
> [<c010d250>] (show_stack) from [<c051b8fc>] (dump_stack+0xbc/0xe8)
> [<c051b8fc>] (dump_stack) from [<c0126ed8>] (__warn+0xf0/0x108)
> [<c0126ed8>] (__warn) from [<c0126f64>] (warn_slowpath_fmt+0x74/0xb8)
> [<c0126f64>] (warn_slowpath_fmt) from [<c056dcb8>]
> (clk_core_unprepare+0x33c/0x470)
> [<c056dcb8>] (clk_core_unprepare) from [<c056de10>]
> (clk_unprepare+0x24/0x2c)
> [<c056de10>] (clk_unprepare) from [<c073f9dc>]
> (__dwc2_lowlevel_hw_disable+0x44/0xa0)
> [<c073f9dc>] (__dwc2_lowlevel_hw_disable) from [<c0740188>]
> (dwc2_driver_probe+0x2d4/0x6ac)
> [<c0740188>] (dwc2_driver_probe) from [<c0653640>]
> (platform_drv_probe+0x6c/0xa4)
> [<c0653640>] (platform_drv_probe) from [<c0650bdc>]
> (really_probe+0x200/0x4fc)
> [<c0650bdc>] (really_probe) from [<c0651040>]
> (driver_probe_device+0x78/0x1fc)
> [<c0651040>] (driver_probe_device) from [<c064ea78>]
> (bus_for_each_drv+0x74/0xb8)
> [<c064ea78>] (bus_for_each_drv) from [<c065093c>]
> (__device_attach+0xd4/0x16c)
> [<c065093c>] (__device_attach) from [<c064fa3c>]
> (bus_probe_device+0x88/0x90)
> [<c064fa3c>] (bus_probe_device) from [<c064ff54>]
> (deferred_probe_work_func+0x3c/0xd0)
> [<c064ff54>] (deferred_probe_work_func) from [<c0148a5c>]
> (process_one_work+0x234/0x7dc)
> [<c0148a5c>] (process_one_work) from [<c0149048>] (worker_thread+0x44/0x51c)
> [<c0149048>] (worker_thread) from [<c015039c>] (kthread+0x158/0x1a0)
> [<c015039c>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
> Exception stack(0xee923fb0 to 0xee923ff8)
> ...
> irq event stamp: 37073
> hardirqs last  enabled at (37081): [<c019d624>] console_unlock+0x430/0x6cc
> hardirqs last disabled at (37108): [<c019d348>] console_unlock+0x154/0x6cc
> softirqs last  enabled at (37124): [<c010174c>] __do_softirq+0x50c/0x608
> softirqs last disabled at (37135): [<c0130218>] irq_exit+0x168/0x16c
> ---[ end trace f55f4b28f3080c13 ]---
> ------------[ cut here ]------------
> WARNING: CPU: 3 PID: 49 at drivers/regulator/core.c:2603
> _regulator_disable+0x180/0x1d8
> unbalanced disables for VUOTG_3.0V
> Modules linked in:
> CPU: 3 PID: 49 Comm: kworker/3:1 Tainted: G        W
> 5.8.0-rc5-next-20200714-00003-g105f360ba595-dirty #8758
> Hardware name: Samsung Exynos (Flattened Device Tree)
> Workqueue: events deferred_probe_work_func
> [<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
> [<c010d250>] (show_stack) from [<c051b8fc>] (dump_stack+0xbc/0xe8)
> [<c051b8fc>] (dump_stack) from [<c0126ed8>] (__warn+0xf0/0x108)
> [<c0126ed8>] (__warn) from [<c0126f64>] (warn_slowpath_fmt+0x74/0xb8)
> [<c0126f64>] (warn_slowpath_fmt) from [<c0585e78>]
> (_regulator_disable+0x180/0x1d8)
> [<c0585e78>] (_regulator_disable) from [<c0585f04>]
> (regulator_disable+0x34/0xe0)
> [<c0585f04>] (regulator_disable) from [<c0587ef8>]
> (regulator_bulk_disable+0x28/0xb0)
> [<c0587ef8>] (regulator_bulk_disable) from [<c0740188>]
> (dwc2_driver_probe+0x2d4/0x6ac)
> [<c0740188>] (dwc2_driver_probe) from [<c0653640>]
> (platform_drv_probe+0x6c/0xa4)
> [<c0653640>] (platform_drv_probe) from [<c0650bdc>]
> (really_probe+0x200/0x4fc)
> [<c0650bdc>] (really_probe) from [<c0651040>]
> (driver_probe_device+0x78/0x1fc)
> [<c0651040>] (driver_probe_device) from [<c064ea78>]
> (bus_for_each_drv+0x74/0xb8)
> [<c064ea78>] (bus_for_each_drv) from [<c065093c>]
> (__device_attach+0xd4/0x16c)
> [<c065093c>] (__device_attach) from [<c064fa3c>]
> (bus_probe_device+0x88/0x90)
> [<c064fa3c>] (bus_probe_device) from [<c064ff54>]
> (deferred_probe_work_func+0x3c/0xd0)
> [<c064ff54>] (deferred_probe_work_func) from [<c0148a5c>]
> (process_one_work+0x234/0x7dc)
> [<c0148a5c>] (process_one_work) from [<c0149048>] (worker_thread+0x44/0x51c)
> [<c0149048>] (worker_thread) from [<c015039c>] (kthread+0x158/0x1a0)
> [<c015039c>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
> Exception stack(0xee923fb0 to 0xee923ff8)
> ...
> irq event stamp: 37243
> hardirqs last  enabled at (37251): [<c019d624>] console_unlock+0x430/0x6cc
> hardirqs last disabled at (37274): [<c0ac0790>] __schedule+0xd8/0x860
> softirqs last  enabled at (37270): [<c010174c>] __do_softirq+0x50c/0x608
> softirqs last disabled at (37291): [<c0130218>] irq_exit+0x168/0x16c
> ---[ end trace f55f4b28f3080c14 ]---
> Failed to disable vusb_a: -5
> dwc2: probe of 12480000.hsotg failed with error -22
> 8<--- cut here ---
> Unable to handle kernel NULL pointer dereference at virtual address 00000004
> pgd = (ptrval)
> [00000004] *pgd=00000000
> Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 3 PID: 87 Comm: kworker/3:2 Tainted: G        W
> 5.8.0-rc5-next-20200714-00003-g105f360ba595-dirty #8758
> Hardware name: Samsung Exynos (Flattened Device Tree)
> Workqueue:  0x0 (rcu_gp)
> PC is at process_one_work+0x44/0x7dc
> LR is at 0xedc226d0
> ...
> Process kworker/3:2 (pid: 87, stack limit = 0x(ptrval))
> Stack: (0xeda03f00 to 0xeda04000)
> ...
> [<c014886c>] (process_one_work) from [<c0149048>] (worker_thread+0x44/0x51c)
> [<c0149048>] (worker_thread) from [<c015039c>] (kthread+0x158/0x1a0)
> [<c015039c>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
> Exception stack(0xeda03fb0 to 0xeda03ff8)
> ...
> ---[ end trace f55f4b28f3080c15 ]---
> note: kworker/3:2[87] exited with preempt_count 1
> 
> Best regards
> 

I guess you build driver in (hsotg->dr_mode == USB_DR_MODE_PERIPHERAL) 
and this is why call of dwc2_lowlevel_hw_disable() at 'error:' label 
create issue. Could you please test on your setup follow implementation:
...
error:
	if (hsotg->dr_mode != USB_DR_MODE_PERIPHERAL)
		dwc2_lowlevel_hw_disable(hsotg);
	return retval;
}
...

Thanks,
Minas





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