Re: [Intel-wired-lan] [PATCH iwl-net] i40e: Fix waiting for queues of all VSIs to be disabled

From: Jacob Keller <jacob.e.keller@intel.com>
To: Ivan Vecera <ivecera@redhat.com>, <intel-wired-lan@lists.osuosl.org>
Cc: Wojciech Drewek <wojciech.drewek@intel.com>,
	"open list:NETWORKING DRIVERS" <netdev@vger.kernel.org>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Neerav Parikh <neerav.parikh@intel.com>,
	open list <linux-kernel@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Tony Nguyen <anthony.l.nguyen@intel.com>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [Intel-wired-lan] [PATCH iwl-net] i40e: Fix waiting for queues of all VSIs to be disabled
Date: Wed, 8 Nov 2023 09:54:07 -0800	[thread overview]
Message-ID: <0a203988-1062-4dc8-96f6-cab800c03026@intel.com> (raw)
In-Reply-To: <20231108160104.86140-1-ivecera@redhat.com>

On 11/8/2023 8:01 AM, Ivan Vecera wrote:
> The function i40e_pf_wait_queues_disabled() iterates all PF's VSIs
> up to 'pf->hw.func_caps.num_vsis' but this is incorrect because
> the real number of VSIs can be up to 'pf->num_alloc_vsi' that
> can be higher. Fix this loop.

This confused me at first, but as described in i40e_probe:

>         /* The number of VSIs reported by the FW is the minimum guaranteed
>          * to us; HW supports far more and we share the remaining pool with
>          * the other PFs. We allocate space for more than the guarantee with
>          * the understanding that we might not get them all later.
>          */
>         if (pf->hw.func_caps.num_vsis < I40E_MIN_VSI_ALLOC)
>                 pf->num_alloc_vsi = I40E_MIN_VSI_ALLOC;
>         else
>                 pf->num_alloc_vsi = pf->hw.func_caps.num_vsis;

The func_caps.num_vsis is really a minimum guaranteed amount and a
single PF could get more from the shared pool.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>

> 
> Fixes: 69129dc39fac ("i40e: Modify Tx disable wait flow in case of DCB reconfiguration")
> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index 6a2907674583..de19d753ba83 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -5340,7 +5340,7 @@ static int i40e_pf_wait_queues_disabled(struct i40e_pf *pf)
>  {
>  	int v, ret = 0;
>  
> -	for (v = 0; v < pf->hw.func_caps.num_vsis; v++) {
> +	for (v = 0; v < pf->num_alloc_vsi; v++) {
>  		if (pf->vsi[v]) {
>  			ret = i40e_vsi_wait_queues_disabled(pf->vsi[v]);
>  			if (ret)
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