On 1/8/2020 2:32 AM, Jason Gunthorpe wrote:
> On Thu, Dec 12, 2019 at 01:30:22PM +0200, Leon Romanovsky wrote:
>
>> @@ -2627,7 +2626,11 @@ struct ib_device {
>> struct rcu_head rcu_head;
>>
>> struct list_head event_handler_list;
>> - spinlock_t event_handler_lock;
>> + /* Protects event_handler_list */
>> + struct rw_semaphore event_handler_rwsem;
>> +
>> + /* Protects QP's event_handler calls and open_qp list */
>> + spinlock_t event_handler_lock;
>
> This only protects the open_qp list really, the event handler call
> doesn't need a spinlock. So lets name it properly. open_list_lock ?
>
Yes. it protects open_qp list and event handler is called for each list
item. So it doesn't really need to protect event handler calls.
> It is sort of weird that we globally serialize all the qp event
> handlers? ie that this lock isn't in the ib_qp.
>
It probably isn't in each ib_qp because ib_qp is in hundred thousands
and xrc qp events are not so frequent event that can get contented.
So I think per device qp list lock seems fine.
