Re: [PATCH V2] drm/xe: Access port only after lock acquired

[Nirmoy Das <nirmoy.das@linux.intel.com>]

Hi Tejas,

On 6/4/2024 12:45 PM, Tejas Upadhyay wrote:
> Currently, port is accessed before lock of port is acquired.
> As followed at other places, lets acquire lock before accessing
> for even better sync up.

The lock is for protecting port->active list so think the code here is 
fine.


Regards,

Nirmoy

> V2:
>    - Add port->active check under lock
>
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_execlist.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_execlist.c b/drivers/gpu/drm/xe/xe_execlist.c
> index db906117db6d..fcbc3bac1ebe 100644
> --- a/drivers/gpu/drm/xe/xe_execlist.c
> +++ b/drivers/gpu/drm/xe/xe_execlist.c
> @@ -210,15 +210,16 @@ static void xe_execlist_port_wake_locked(struct xe_execlist_port *port,
>   
>   static void xe_execlist_make_active(struct xe_execlist_exec_queue *exl)
>   {
> -	struct xe_execlist_port *port = exl->port;
> +	struct xe_execlist_port *port;
>   	enum xe_exec_queue_priority priority = exl->q->sched_props.priority;
>   
>   	XE_WARN_ON(priority == XE_EXEC_QUEUE_PRIORITY_UNSET);
>   	XE_WARN_ON(priority < 0);
> -	XE_WARN_ON(priority >= ARRAY_SIZE(exl->port->active));
>   
> -	spin_lock_irq(&port->lock);
> +	spin_lock_irq(&exl->port->lock);
>   
> +	XE_WARN_ON(priority >= ARRAY_SIZE(exl->port->active));
> +	port = exl->port;
>   	if (exl->active_priority != priority &&
>   	    exl->active_priority != XE_EXEC_QUEUE_PRIORITY_UNSET) {
>   		/* Priority changed, move it to the right list */