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From: "Alastair D'Silva" <alastair@au1.ibm.com>
To: Frederic Barrat <fbarrat@linux.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, andrew.donnellan@au1.ibm.com,
	clombard@linux.ibm.com
Cc: groug@kaod.org
Subject: Re: [PATCH 01/11] powerpc/powernv/ioda: Fix ref count for devices with their own PE
Date: Tue, 10 Sep 2019 10:20:56 +1000
Message-ID: <02d7bbc21e915012efe3c0178a4c0327cb016822.camel@au1.ibm.com> (raw)
In-Reply-To: <20190909154600.19917-2-fbarrat@linux.ibm.com>

On Mon, 2019-09-09 at 17:45 +0200, Frederic Barrat wrote:
> Taking a reference on the pci_dev structure was required with initial
> commit 184cd4a3b962 ("powerpc/powernv: PCI support for p7IOC under
> OPAL v2"), where we were storing the pci_dev in the pci_dn structure.
> 
> However, the pci_dev was later removed from the pci_dn structure, but
> the reference was kept. See commit 902bdc57451c
> ("powerpc/powernv/idoa:
> Remove unnecessary pcidev from pci_dn").
> 
> The pnv_ioda_pe structure life cycle is the same as the pci_dev
> structure, the PE is freed when the device is released. So we don't
> need a reference for the pci_dev stored in the PE, otherwise the
> pci_dev will never be released. Which is not really a surprise as the
> comment (removed here as no longer needed) was stating as much.
> 
> Fixes: 902bdc57451c ("powerpc/powernv/idoa: Remove unnecessary pcidev
> from pci_dn")
> Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
> ---
>  arch/powerpc/platforms/powernv/pci-ioda.c | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
> b/arch/powerpc/platforms/powernv/pci-ioda.c
> index d8080558d020..92767f006f20 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -1062,14 +1062,6 @@ static struct pnv_ioda_pe
> *pnv_ioda_setup_dev_PE(struct pci_dev *dev)
>  		return NULL;
>  	}
>  
> -	/* NOTE: We get only one ref to the pci_dev for the pdn, not
> for the
> -	 * pointer in the PE data structure, both should be destroyed
> at the
> -	 * same time. However, this needs to be looked at more closely
> again
> -	 * once we actually start removing things (Hotplug, SR-IOV,
> ...)
> -	 *
> -	 * At some point we want to remove the PDN completely anyways
> -	 */
> -	pci_dev_get(dev);
>  	pdn->pe_number = pe->pe_number;
>  	pe->flags = PNV_IODA_PE_DEV;
>  	pe->pdev = dev;
> @@ -1084,7 +1076,6 @@ static struct pnv_ioda_pe
> *pnv_ioda_setup_dev_PE(struct pci_dev *dev)
>  		pnv_ioda_free_pe(pe);
>  		pdn->pe_number = IODA_INVALID_PE;
>  		pe->pdev = NULL;
> -		pci_dev_put(dev);
>  		return NULL;
>  	}
>  
> @@ -1228,7 +1219,7 @@ static struct pnv_ioda_pe
> *pnv_ioda_setup_npu_PE(struct pci_dev *npu_pdev)
>  			 */
>  			dev_info(&npu_pdev->dev,
>  				"Associating to existing PE %x\n",
> pe_num);
> -			pci_dev_get(npu_pdev);
> +			pci_dev_get(npu_pdev); // still needed after
> 902bdc57451c ?
>  			npu_pdn = pci_get_pdn(npu_pdev);
>  			rid = npu_pdev->bus->number << 8 | npu_pdn-
> >devfn;
>  			npu_pdn->pe_number = pe_num;

Reviewed-by: Alastair D'Silva <alastair@d-silva.org>

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819


  reply index

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-09 15:45 [PATCH 00/11] opencapi: enable card reset and link retraining Frederic Barrat
2019-09-09 15:45 ` [PATCH 01/11] powerpc/powernv/ioda: Fix ref count for devices with their own PE Frederic Barrat
2019-09-10  0:20   ` Alastair D'Silva [this message]
2019-09-26 16:44   ` Andrew Donnellan
2019-09-26 17:15     ` Frederic Barrat
2019-09-27  6:54       ` Alexey Kardashevskiy
2019-11-12 17:38         ` Frederic Barrat
2019-11-18  1:04           ` Alistair Popple
2019-11-18  1:24             ` Oliver O'Halloran
2019-11-18  2:36               ` Alistair Popple
2019-11-18 18:21                 ` Frederic Barrat
2019-09-09 15:45 ` [PATCH 02/11] powerpc/powernv/ioda: Protect PE list Frederic Barrat
2019-09-10  0:34   ` Alastair D'Silva
2019-11-19 12:55     ` Frederic Barrat
2019-11-19 13:22       ` Oliver O'Halloran
2019-11-19 14:36         ` Frederic Barrat
2019-11-19  5:55   ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 03/11] powerpc/powernv/ioda: set up PE on opencapi device when enabling Frederic Barrat
2019-09-10  0:38   ` Alastair D'Silva
2019-09-27 16:43   ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 04/11] powerpc/powernv/ioda: Release opencapi device Frederic Barrat
2019-09-10  0:56   ` Alastair D'Silva
2019-11-19 17:32     ` Frederic Barrat
2019-11-19  7:08   ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 05/11] powerpc/powernv/ioda: Find opencapi slot for a device node Frederic Barrat
2019-09-10  0:57   ` Alastair D'Silva
2019-11-19  1:26   ` Andrew Donnellan
2019-11-19 14:33     ` Frederic Barrat
2019-09-09 15:45 ` [PATCH 06/11] pci/hotplug/pnv-php: Remove erroneous warning Frederic Barrat
2019-09-10  0:58   ` Alastair D'Silva
2019-11-19  5:00   ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 07/11] pci/hotplug/pnv-php: Improve error msg on power state change failure Frederic Barrat
2019-09-10  0:59   ` Alastair D'Silva
2019-11-19  2:23   ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 08/11] pci/hotplug/pnv-php: Register opencapi slots Frederic Barrat
2019-09-10  1:00   ` Alastair D'Silva
2019-11-19  5:18   ` Andrew Donnellan
2019-11-19 15:15     ` Frederic Barrat
2019-09-09 15:45 ` [PATCH 09/11] pci/hotplug/pnv-php: Relax check when disabling slot Frederic Barrat
2019-09-10  1:00   ` Alastair D'Silva
2019-09-27 15:56   ` Andrew Donnellan
2019-09-09 15:45 ` [PATCH 10/11] pci/hotplug/pnv-php: Wrap warnings in macro Frederic Barrat
2019-09-10  1:03   ` Alastair D'Silva
2019-09-26 17:18   ` Andrew Donnellan
2019-09-09 15:46 ` [PATCH 11/11] ocxl: Add PCI hotplug dependency to Kconfig Frederic Barrat
2019-09-10  1:03   ` Alastair D'Silva
2019-09-26 17:11   ` Andrew Donnellan
2019-09-24  4:24 ` [PATCH 00/11] opencapi: enable card reset and link retraining Alexey Kardashevskiy
2019-09-24  6:39   ` Frederic Barrat
2019-09-25  0:20     ` Alexey Kardashevskiy

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