Re: [PATCH 07/22] drm/tegra: Remove module ownership from the tegra_fb_ops

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On 13.06.2017 16:43, Thierry Reding wrote:
> On Tue, May 23, 2017 at 03:14:22AM +0300, Dmitry Osipenko wrote:
>> The framebuffers console fbcon_startup() increments the tegra_drm module
>> 'use' refcount via try_module_get(), causing an interlock of the DRM subsys
>> and the tegra_drm modules. In result, the tegra_drm module can't be unloaded
>> using rmmod.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
>> ---
>>  drivers/gpu/drm/tegra/fb.c | 1 -
>>  1 file changed, 1 deletion(-)
> 
> That's done on purpose because otherwise you could just rip out the
> driver from under the framebuffer emulation and things would crash.
> 
> My understanding is that the right way to unload a module is to unbind
> the driver first (which will cause the framebuffer to be removed and
> hence the reference to be dropped) before the rmmod.
> 
> Thierry
> 

Aha, interesting. I'll try the unbinding and will drop this patch from the
series, thank you for the clarification. I haven't observed any crashes on a
module reloading (framebuffer detached/attached just fine), maybe I was lucky then.

-- 
Dmitry
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