Re: [PATCH 15/24] drm/amd/display: Fix deadlock when flushing irq

[Andrey Grodzovsky <Andrey.Grodzovsky-5C7GfCeVMHo@public.gmane.org>]

What this spin lock is protecting here ? Seems to me it's just a read of 
an array element which is always there.

Regarding subsequent remove_timer_handler and timer queue destruction it 
seems to me to be obsolete code, I don't think DAL is still using the 
timer queue,

so seems to me everything related to it should be removed.

Thanks,

Andrey


On 01/18/2018 04:03 PM, Harry Wentland wrote:
> From: Mikita Lipski <mikita.lipski@amd.com>
>
> Lock irq table when reading a work in queue,
> unlock to flush the work, lock again till all tasks
> are cleared
>
> Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
> Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
> index 1874b6cee6af..fb60c91a1bfe 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c
> @@ -400,14 +400,15 @@ void amdgpu_dm_irq_fini(struct amdgpu_device *adev)
>   {
>   	int src;
>   	struct irq_list_head *lh;
> +	unsigned long irq_table_flags;
>   	DRM_DEBUG_KMS("DM_IRQ: releasing resources.\n");
> -
>   	for (src = 0; src < DAL_IRQ_SOURCES_NUMBER; src++) {
> -
> +		DM_IRQ_TABLE_LOCK(adev, irq_table_flags);
>   		/* The handler was removed from the table,
>   		 * it means it is safe to flush all the 'work'
>   		 * (because no code can schedule a new one). */
>   		lh = &adev->dm.irq_handler_list_low_tab[src];
> +		DM_IRQ_TABLE_UNLOCK(adev, irq_table_flags);
>   		flush_work(&lh->work);
>   	}
>   

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