Re: [Intel-wired-lan] [PATCH v3 net] idpf: disable PTM on probe failure and on remove

> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf
> Of Myeonghun Pak
> Sent: Monday, July 20, 2026 4:35 PM
> To: Nguyen, Anthony L <[email protected]>; Kitszel,
> Przemyslaw <[email protected]>; intel-wired-
> [email protected]
> Cc: Olech, Milena <[email protected]>; Tantilov, Emil S
> <[email protected]>; Mina Almasry <[email protected]>;
> Andrew Lunn <[email protected]>; David S . Miller
> <[email protected]>; Eric Dumazet <[email protected]>; Jakub
> Kicinski <[email protected]>; Paolo Abeni <[email protected]>;
> [email protected]; [email protected]; Myeonghun Pak
> <[email protected]>; Ijae Kim <[email protected]>
> Subject: [Intel-wired-lan] [PATCH v3 net] idpf: disable PTM on probe
> failure and on remove
> 
> idpf_probe() enables PCIe Precision Time Measurement with
> pci_enable_ptm(), which takes a reference on the device and on every
> PTM-capable device up the path to the PTM Root.
> 
> Neither the probe error path nor idpf_remove() drops that reference,
> so the PTM enable counts of this device and of its upstream path stay
> elevated with no bound driver, and the device's PTM control bits
> remain set.  pcim_enable_device() only arranges for
> pci_disable_device() and does not undo the PTM enable.
> 
> Add the matching pci_disable_ptm() to the common probe unwind and to
> idpf_remove().  pci_enable_ptm() failure is not fatal here, so guard
> both calls with pcie_ptm_enabled(): pci_disable_ptm() decrements
> dev->ptm_enable_cnt unconditionally and then recurses upstream, so
> calling it after a failed enable would drive this device's count
> negative and wrongly decrement parents shared with other endpoints.
> 
> This issue was identified during our ongoing static-analysis research
> while reviewing kernel code.
> 
> Fixes: 8d5e12c5921c ("idpf: add initial PTP support")
> Co-developed-by: Ijae Kim <[email protected]>
> Signed-off-by: Ijae Kim <[email protected]>
> Signed-off-by: Myeonghun Pak <[email protected]>
> ---
> Changes in v3:
> - Rebased; aa8671af0c38 ("PCI/PTM: Drop pci_enable_ptm() granularity
>   parameter") changed the call signature, so v2 no longer applied.
> - Guard both pci_disable_ptm() calls with pcie_ptm_enabled(), as
>   pci_disable_ptm() is refcounted and recurses upstream since
>   e1092d5e15e6 ("PCI/PTM: Do not enable PTM automatically for Root and
>   Switch Upstream Ports").  Raised by Tony Nguyen.
> - Dropped the v2 claim that pci_disable_ptm() is a no-op when PTM was
> not
>   enabled; that is no longer true.
> 
> Changes in v2:
> - Disable PTM in the probe error path, as requested by Emil Tantilov.
> 
>  drivers/net/ethernet/intel/idpf/idpf_main.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_main.c
> b/drivers/net/ethernet/intel/idpf/idpf_main.c
> index ab3c409..97bafeb 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_main.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_main.c
> @@ -159,6 +159,8 @@ destroy_wqs:
>  	mutex_destroy(&adapter->queue_lock);
>  	mutex_destroy(&adapter->vc_buf_lock);
> 
> +	if (pcie_ptm_enabled(pdev))
> +		pci_disable_ptm(pdev);
>  	pci_set_drvdata(pdev, NULL);
>  	kfree(adapter);
>  }
> @@ -266,7 +268,7 @@ static int idpf_probe(struct pci_dev *pdev, const
> struct pci_device_id *ent)
>  	if (err) {
>  		pci_err(pdev, "DMA configuration failed: %pe\n",
> ERR_PTR(err));
> 
> -		goto err_free;
> +		goto err_disable_ptm;
>  	}
> 
>  	pci_set_master(pdev);
> @@ -279,7 +281,7 @@ static int idpf_probe(struct pci_dev *pdev, const
> struct pci_device_id *ent)
>  	if (!adapter->init_wq) {
>  		dev_err(dev, "Failed to allocate init workqueue\n");
>  		err = -ENOMEM;
> -		goto err_free;
> +		goto err_disable_ptm;
>  	}
> 
>  	adapter->serv_wq = alloc_workqueue("%s-%s-service", @@ -366,6
> +368,9 @@ err_mbx_wq_alloc:
>  	destroy_workqueue(adapter->serv_wq);
>  err_serv_wq_alloc:
>  	destroy_workqueue(adapter->init_wq);
> +err_disable_ptm:
> +	if (pcie_ptm_enabled(pdev))
> +		pci_disable_ptm(pdev);
>  err_free:
>  	kfree(adapter);
>  	return err;
> --
> 2.47.1

Reviewed-by: Aleksandr Loktionov <[email protected]>