[Intel-wired-lan] [next PATCH S66 3/3] i40e: don't hold RTNL lock for the entire reset

[Intel-wired-lan] [next PATCH S66 3/3] i40e: don't hold RTNL lock for the entire reset

[Keller, Jacob E]

ACK

> -----Original Message-----
> From: Michael, Alice
> Sent: Monday, March 27, 2017 3:42 AM
> To: intel-wired-lan at lists.osuosl.org
> Cc: Keller, Jacob E <jacob.e.keller@intel.com>
> Subject: [next PATCH S66 3/3] i40e: don't hold RTNL lock for the entire reset
> 
> From: Jacob Keller <jacob.e.keller@intel.com>
> 
> We recently refactored i40e_do_reset() and its friends to be able to
> hold the RTNL lock only for the portions that actually need to be
> protected. However, a separate refactoring added several new callers of
> these functions during the PCIe error recovery and suspend/resume
> cycles.
> 
> When merging the changes together, it was not noticed that we could
> reduce the RTNL scope by letting the reset function handle the lock
> itself, as previously it was not possible.
> 
> Fix this by replacing these call sites to indicate that the reset
> function should handle its own lock. This enables multiple PFs to reset
> or resume simultaneously without serializing the resets via the RTNL
> lock. The end result is that on systems with lots of PFs and VFs the
> resets don't stall waiting for each other to finish.
> 
> It is probable that we can also do the same for i40e_do_reset_safe, but
> this author did not research that change carefully enough to be
> confident.
> 
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> Change-ID: I33b848e0dd0aee465b604b9ec558b9d7519be3eb
> ---
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 27 +++++++--------------------
>  1 file changed, 7 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c
> b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index fcfab36..3d9c898 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -6343,9 +6343,7 @@ static void i40e_reset_subtask(struct i40e_pf *pf)
>  	if (reset_flags &&
>  	    !test_bit(__I40E_DOWN, &pf->state) &&
>  	    !test_bit(__I40E_CONFIG_BUSY, &pf->state)) {
> -		rtnl_lock();
> -		i40e_do_reset(pf, reset_flags, true);
> -		rtnl_unlock();
> +		i40e_do_reset(pf, reset_flags, false);
>  	}
>  }
> 
> @@ -11514,11 +11512,8 @@ static pci_ers_result_t
> i40e_pci_error_detected(struct pci_dev *pdev,
>  	}
> 
>  	/* shutdown all operations */
> -	if (!test_bit(__I40E_SUSPENDED, &pf->state)) {
> -		rtnl_lock();
> -		i40e_prep_for_reset(pf, true);
> -		rtnl_unlock();
> -	}
> +	if (!test_bit(__I40E_SUSPENDED, &pf->state))
> +		i40e_prep_for_reset(pf, false);
> 
>  	/* Request a slot reset */
>  	return PCI_ERS_RESULT_NEED_RESET;
> @@ -11584,9 +11579,7 @@ static void i40e_pci_error_resume(struct pci_dev
> *pdev)
>  	if (test_bit(__I40E_SUSPENDED, &pf->state))
>  		return;
> 
> -	rtnl_lock();
> -	i40e_handle_reset_warning(pf, true);
> -	rtnl_unlock();
> +	i40e_handle_reset_warning(pf, false);
>  }
> 
>  /**
> @@ -11661,9 +11654,7 @@ static void i40e_shutdown(struct pci_dev *pdev)
>  	if (pf->wol_en && (pf->flags &
> I40E_FLAG_WOL_MC_MAGIC_PKT_WAKE))
>  		i40e_enable_mc_magic_wake(pf);
> 
> -	rtnl_lock();
> -	i40e_prep_for_reset(pf, true);
> -	rtnl_unlock();
> +	i40e_prep_for_reset(pf, false);
> 
>  	wr32(hw, I40E_PFPM_APM,
>  	     (pf->wol_en ? I40E_PFPM_APM_APME_MASK : 0));
> @@ -11695,9 +11686,7 @@ static int i40e_suspend(struct pci_dev *pdev,
> pm_message_t state)
>  	if (pf->wol_en && (pf->flags &
> I40E_FLAG_WOL_MC_MAGIC_PKT_WAKE))
>  		i40e_enable_mc_magic_wake(pf);
> 
> -	rtnl_lock();
> -	i40e_prep_for_reset(pf, true);
> -	rtnl_unlock();
> +	i40e_prep_for_reset(pf, false);
> 
>  	wr32(hw, I40E_PFPM_APM, (pf->wol_en ?
> I40E_PFPM_APM_APME_MASK : 0));
>  	wr32(hw, I40E_PFPM_WUFC, (pf->wol_en ?
> I40E_PFPM_WUFC_MAG_MASK : 0));
> @@ -11743,9 +11732,7 @@ static int i40e_resume(struct pci_dev *pdev)
>  	/* handling the reset will rebuild the device state */
>  	if (test_and_clear_bit(__I40E_SUSPENDED, &pf->state)) {
>  		clear_bit(__I40E_DOWN, &pf->state);
> -		rtnl_lock();
> -		i40e_reset_and_rebuild(pf, false, true);
> -		rtnl_unlock();
> +		i40e_reset_and_rebuild(pf, false, false);
>  	}
> 
>  	return 0;
> --
> 2.9.3