Subject: Re: ixgbe: pci_get_device() call without counterpart call of pci_dev_put()

From: Jeff Kirsher <[email-masked]>
Date: Sun, 09 Dec 2012 23:17:44 -0800

On 12/09/2012 01:47 AM, Elena Gurevich wrote:
> Hi all,
> I am pioneer in linux device drivers here and using Intel 82599 NIC as
> reference model, 
> During investigation to drivers sources I found the suspicious code:  
>
> Is code sequence (1)   and (2) the possible device reference count leakage
> ???
>
>
> Thanks a lot in advance
> Lena
>
> --------snipped from ixgbe_main.c  file function ixgbe_io_error_detected()
> -----------
>
> . . . 
> 		/* Find the pci device of the offending VF */
> 		vfdev = pci_get_device(PCI_VENDOR_ID_INTEL, device_id,
> NULL);
> 		while (vfdev) {
> 			if (vfdev->devfn == (req_id & 0xFF))
> 				break;
> <------------------------------      (1) leaves the loop with successful get
> call  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
> 			vfdev = pci_get_device(PCI_VENDOR_ID_INTEL,
> 					       device_id, vfdev);
> 		}
> 		/*
> 		 * There's a slim chance the VF could have been hot plugged,
> 		 * so if it is no longer present we don't need to issue the
> 		 * VFLR.  Just clean up the AER in that case.
> 		 */
> 		if (vfdev) {
> 			e_dev_err("Issuing VFLR to VF %d\n", vf);
> 			pci_write_config_dword(vfdev, 0xA8, 0x00008000);
> 		}
>
> 		pci_cleanup_aer_uncorrect_error_status(pdev);
> 	}
>
> 	/*
> 	 * Even though the error may have occurred on the other port
> 	 * we still need to increment the vf error reference count for
> 	 * both ports because the I/O resume function will be called
> 	 * for both of them.
> 	 */
> 	adapter->vferr_refcount++;
>
> 	return PCI_ERS_RESULT_RECOVERED;
> <--------------------------------------------  (2) leaves the function
> without put call !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> ----------------------------------  snipped
> -----------------------------------
>
Added Greg Rose (ixgbevf maintainer) & Don Skidmore (ixgbe maintainer)

Since the code you have questions about is dealing with the vf, Greg
will most likely be able to shed some light to your questions.