netdev - Re: [PATCH net v2 1/3] s390/ism: Fix locking for forwarding of IRQs and events to clients

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Date: Fri, 7 Jul 2023 15:37:20 +0200
From: Alexandra Winter <wintera@...ux.ibm.com>
To: Niklas Schnelle <schnelle@...ux.ibm.com>, Paolo Abeni
 <pabeni@...hat.com>,
        Wenjia Zhang <wenjia@...ux.ibm.com>, Jan Karcher <jaka@...ux.ibm.com>,
        Stefan Raspl <raspl@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>
Cc: linux-s390@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v2 1/3] s390/ism: Fix locking for forwarding of IRQs
 and events to clients



On 07.07.23 12:56, Niklas Schnelle wrote:
[...]
> Instead of expanding the use of the clients_lock further add a separate
> array in struct ism_dev which references clients subscribed to the
> device's events and IRQs. This array is protected by ism->lock which is
> already taken in ism_handle_irq() and can be taken outside the IRQ
> handler when adding/removing subscribers or the accessing

				typo? s/the accessing/accessing the/g

> ism->sba_client_arr[]. This also means that the clients_lock is no
> longer taken in IRQ context.
> 

[...]

> @@ -554,6 +577,7 @@ static void ism_dev_add_work_func(struct work_struct *work)
>  						 add_work);
>  
>  	client->add(client->tgt_ism);
> +	ism_setup_forwarding(client, client->tgt_ism);
>  	atomic_dec(&client->tgt_ism->add_dev_cnt);
>  	wake_up(&client->tgt_ism->waitq);
>  }
> @@ -691,7 +715,11 @@ static void ism_dev_remove_work_func(struct work_struct *work)
>  {
>  	struct ism_client *client = container_of(work, struct ism_client,
>  						 remove_work);
> +	unsigned long flags;
>  
> +	spin_lock_irqsave(&client->tgt_ism->lock, flags);
> +	client->tgt_ism->subs[client->id] = NULL;
> +	spin_unlock_irqrestore(&client->tgt_ism->lock, flags);
>  	client->remove(client->tgt_ism);
>  	atomic_dec(&client->tgt_ism->free_clients_cnt);
>  	wake_up(&client->tgt_ism->waitq);

I am not sure I like the new split. here you fix ism_dev_add_work_func() and ism_dev_remove_work_func(),
that you remove in the next patch. But looks functionally ok to me.


Reviewed-by: Alexandra Winter <wintera@...ux.ibm.com>