netdev - Re: [PATCH net 3/4] ibmvnic: don't spin in tasklet

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Date:   Sat, 22 Jan 2022 16:32:12 -0800
From:   Dany Madden <drt@...ux.ibm.com>
To:     Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
Cc:     netdev@...r.kernel.org, Brian King <brking@...ux.ibm.com>,
        Rick Lindsley <ricklind@...ux.ibm.com>
Subject: Re: [PATCH net 3/4] ibmvnic: don't spin in tasklet

On 2022-01-21 18:59, Sukadev Bhattiprolu wrote:
> ibmvnic_tasklet() continuously spins waiting for responses to all
> capability requests. It does this to avoid encountering an error
> during initialization of the vnic. However if there is a bug in the
> VIOS and we do not receive a response to one or more queries the
> tasklet ends up spinning continuously leading to hard lock ups.
> 
> If we fail to receive a message from the VIOS it is reasonable to
> timeout the login attempt rather than spin indefinitely in the tasklet.
> 
> Fixes: 249168ad07cd ("ibmvnic: Make CRQ interrupt tasklet wait for all
> capabilities crqs")
> Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
Reviewed-by: Dany Madden <drt@...ux.ibm.com>

> ---
>  drivers/net/ethernet/ibm/ibmvnic.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c
> b/drivers/net/ethernet/ibm/ibmvnic.c
> index acd488310bbc..682a440151a8 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -5491,12 +5491,6 @@ static void ibmvnic_tasklet(struct 
> tasklet_struct *t)
>  			ibmvnic_handle_crq(crq, adapter);
>  			crq->generic.first = 0;
>  		}
> -
> -		/* remain in tasklet until all
> -		 * capabilities responses are received
> -		 */
> -		if (!adapter->wait_capability)
> -			done = true;
>  	}
>  	/* if capabilities CRQ's were sent in this tasklet, the following
>  	 * tasklet must wait until all responses are received