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Date: Fri, 18 Aug 2023 14:20:51 +0200
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Leon Romanovsky <leon@...nel.org>, Tony Nguyen
<anthony.l.nguyen@...el.com>, Jesse Brandeburg <jesse.brandeburg@...el.com>
CC: <intel-wired-lan@...ts.osuosl.org>, <netdev@...r.kernel.org>, "Mateusz
Polchlopek" <mateusz.polchlopek@...el.com>, Jacob Keller
<jacob.e.keller@...el.com>
Subject: Re: [PATCH iwl-next] ice: store VF's pci_dev ptr in ice_vf
On 8/16/23 16:31, Leon Romanovsky wrote:
> On Wed, Aug 16, 2023 at 04:54:54AM -0400, Przemek Kitszel wrote:
>> Extend struct ice_vf by vfdev.
>> Calculation of vfdev falls more nicely into ice_create_vf_entries().
>>
>> Caching of vfdev enables simplification of ice_restore_all_vfs_msi_state().
>
> I see that old code had access to pci_dev * of VF without any locking
> from concurrent PCI core access. How is it protected? How do you make
> sure that vfdev is valid?
>
> Generally speaking, it is rarely good idea to cache VF pci_dev pointers
> inside driver.
>
> Thanks
Overall, I do agree that ice driver, as a whole, has room for
improvement in terms of synchronization, objects lifetime, and similar.
In this particular case, I don't see any reason of PCI reconfiguration
during VF lifetime, but likely I'm missing something?
Other thing is that I've forgot to call pci_dev_put(vfdev),
thus this pointer will remain valid forever :~/
Assuming proper refcount balancing in v2, what could go wrong here?
>
>>
>> Reviewed-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
>> Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>
>> Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>
>> ---
>> add/remove: 0/0 grow/shrink: 2/1 up/down: 157/-130 (27)
>> Function old new delta
>> ice_sriov_configure 1712 1866 +154
>> ice_pci_err_resume 168 171 +3
>> ice_restore_all_vfs_msi_state 200 70 -130
>> ---
>> drivers/net/ethernet/intel/ice/ice_main.c | 2 +-
>> drivers/net/ethernet/intel/ice/ice_sriov.c | 40 +++++++++------------
>> drivers/net/ethernet/intel/ice/ice_sriov.h | 4 +--
>> drivers/net/ethernet/intel/ice/ice_vf_lib.h | 2 +-
>> 4 files changed, 21 insertions(+), 27 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
>> index a6dd336d2500..d04498c2fd6d 100644
>> --- a/drivers/net/ethernet/intel/ice/ice_main.c
>> +++ b/drivers/net/ethernet/intel/ice/ice_main.c
>> @@ -5561,7 +5561,7 @@ static void ice_pci_err_resume(struct pci_dev *pdev)
>> return;
>> }
>>
>> - ice_restore_all_vfs_msi_state(pdev);
>> + ice_restore_all_vfs_msi_state(pf);
>>
>> ice_do_reset(pf, ICE_RESET_PFR);
>> ice_service_task_restart(pf);
>> diff --git a/drivers/net/ethernet/intel/ice/ice_sriov.c b/drivers/net/ethernet/intel/ice/ice_sriov.c
>> index 31314e7540f8..48bc8ea55265 100644
>> --- a/drivers/net/ethernet/intel/ice/ice_sriov.c
>> +++ b/drivers/net/ethernet/intel/ice/ice_sriov.c
>> @@ -789,14 +789,19 @@ static const struct ice_vf_ops ice_sriov_vf_ops = {
>> */
>> static int ice_create_vf_entries(struct ice_pf *pf, u16 num_vfs)
>> {
>> + struct pci_dev *pdev = pf->pdev;
>> struct ice_vfs *vfs = &pf->vfs;
>> + struct pci_dev *vfdev = NULL;
>> struct ice_vf *vf;
>> - u16 vf_id;
>> - int err;
>> + u16 vf_pdev_id;
>> + int err, pos;
>>
>> lockdep_assert_held(&vfs->table_lock);
>>
>> - for (vf_id = 0; vf_id < num_vfs; vf_id++) {
>> + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_SRIOV);
>> + pci_read_config_word(pdev, pos + PCI_SRIOV_VF_DID, &vf_pdev_id);
>> +
>> + for (u16 vf_id = 0; vf_id < num_vfs; vf_id++) {
>> vf = kzalloc(sizeof(*vf), GFP_KERNEL);
>> if (!vf) {
>> err = -ENOMEM;
>> @@ -812,6 +817,10 @@ static int ice_create_vf_entries(struct ice_pf *pf, u16 num_vfs)
>>
>> ice_initialize_vf_entry(vf);
>>
>> + do {
>> + vfdev = pci_get_device(pdev->vendor, vf_pdev_id, vfdev);
>> + } while (vfdev && vfdev->physfn != pdev);
>> + vf->vfdev = vfdev;
>> vf->vf_sw_id = pf->first_sw;
>>
>> hash_add_rcu(vfs->table, &vf->entry, vf_id);
>> @@ -1714,26 +1723,11 @@ void ice_print_vfs_mdd_events(struct ice_pf *pf)
>> * Called when recovering from a PF FLR to restore interrupt capability to
>> * the VFs.
>> */
>> -void ice_restore_all_vfs_msi_state(struct pci_dev *pdev)
>> +void ice_restore_all_vfs_msi_state(struct ice_pf *pf)
>> {
>> - u16 vf_id;
>> - int pos;
>> -
>> - if (!pci_num_vf(pdev))
>> - return;
>> + struct ice_vf *vf;
>> + u32 bkt;
>>
>> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_SRIOV);
>> - if (pos) {
>> - struct pci_dev *vfdev;
>> -
>> - pci_read_config_word(pdev, pos + PCI_SRIOV_VF_DID,
>> - &vf_id);
>> - vfdev = pci_get_device(pdev->vendor, vf_id, NULL);
>> - while (vfdev) {
>> - if (vfdev->is_virtfn && vfdev->physfn == pdev)
>> - pci_restore_msi_state(vfdev);
>> - vfdev = pci_get_device(pdev->vendor, vf_id,
>> - vfdev);
>> - }
>> - }
>> + ice_for_each_vf(pf, bkt, vf)
>> + pci_restore_msi_state(vf->vfdev);
>> }
>> diff --git a/drivers/net/ethernet/intel/ice/ice_sriov.h b/drivers/net/ethernet/intel/ice/ice_sriov.h
>> index 346cb2666f3a..06829443d540 100644
>> --- a/drivers/net/ethernet/intel/ice/ice_sriov.h
>> +++ b/drivers/net/ethernet/intel/ice/ice_sriov.h
>> @@ -33,7 +33,7 @@ int
>> ice_get_vf_cfg(struct net_device *netdev, int vf_id, struct ifla_vf_info *ivi);
>>
>> void ice_free_vfs(struct ice_pf *pf);
>> -void ice_restore_all_vfs_msi_state(struct pci_dev *pdev);
>> +void ice_restore_all_vfs_msi_state(struct ice_pf *pf);
>>
>> int
>> ice_set_vf_port_vlan(struct net_device *netdev, int vf_id, u16 vlan_id, u8 qos,
>> @@ -67,7 +67,7 @@ static inline
>> void ice_vf_lan_overflow_event(struct ice_pf *pf, struct ice_rq_event_info *event) { }
>> static inline void ice_print_vfs_mdd_events(struct ice_pf *pf) { }
>> static inline void ice_print_vf_rx_mdd_event(struct ice_vf *vf) { }
>> -static inline void ice_restore_all_vfs_msi_state(struct pci_dev *pdev) { }
>> +static inline void ice_restore_all_vfs_msi_state(struct ice_pf *pf) { }
>>
>> static inline int
>> ice_sriov_configure(struct pci_dev __always_unused *pdev,
>> diff --git a/drivers/net/ethernet/intel/ice/ice_vf_lib.h b/drivers/net/ethernet/intel/ice/ice_vf_lib.h
>> index 48fea6fa0362..57c36e4ccf91 100644
>> --- a/drivers/net/ethernet/intel/ice/ice_vf_lib.h
>> +++ b/drivers/net/ethernet/intel/ice/ice_vf_lib.h
>> @@ -82,7 +82,7 @@ struct ice_vf {
>> struct rcu_head rcu;
>> struct kref refcnt;
>> struct ice_pf *pf;
>> -
>> + struct pci_dev *vfdev;
>> /* Used during virtchnl message handling and NDO ops against the VF
>> * that will trigger a VFR
>> */
>>
>> base-commit: 0ad204c4acb8ba1ed99564b001609e62547bc79d
>> --
>> 2.40.1
>>
>>
>
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