linux-kernel - Re: [Patch Part1 V2 02/17] iommu/vt-d: fix PCI device reference leakage on error recovery path

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Message-ID: <529BE508.7090504@huawei.com>
Date:	Mon, 2 Dec 2013 09:40:24 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Joerg Roedel <joro@...tes.org>,
	David Woodhouse <dwmw2@...radead.org>,
	"Dan Williams" <dan.j.williams@...el.com>,
	Vinod Koul <vinod.koul@...el.com>,
	Ashok Raj <ashok.raj@...el.com>
CC:	<iommu@...ts.linux-foundation.org>, <linux-pci@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <dmaengine@...r.kernel.org>
Subject: Re: [Patch Part1 V2 02/17] iommu/vt-d: fix PCI device reference leakage
 on error recovery path

Reviewed-by: Yijing Wang <wangyijing@...wei.com>

On 2013/11/29 16:50, Jiang Liu wrote:
> Function dmar_parse_dev_scope() should release the PCI device reference
> count gained in function dmar_parse_one_dev_scope() on error recovery,
> otherwise will cause PCI device object leakage.
> 
> This patch also introduces dmar_free_dev_scope(), which will be used
> to support DMAR device hotplug.
> 
> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> ---
>  drivers/iommu/dmar.c |   15 +++++++++++++--
>  include/linux/dmar.h |    1 +
>  2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index 8b452c9..f3043a2 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -72,6 +72,7 @@ static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
>  	struct acpi_dmar_pci_path *path;
>  	int count;
>  
> +	*dev = NULL;
>  	bus = pci_find_bus(segment, scope->bus);
>  	path = (struct acpi_dmar_pci_path *)(scope + 1);
>  	count = (scope->length - sizeof(struct acpi_dmar_device_scope))
> @@ -100,7 +101,6 @@ static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
>  	if (!pdev) {
>  		pr_warn("Device scope device [%04x:%02x:%02x.%02x] not found\n",
>  			segment, scope->bus, path->device, path->function);
> -		*dev = NULL;
>  		return 0;
>  	}
>  	if ((scope->entry_type == ACPI_DMAR_SCOPE_TYPE_ENDPOINT && \
> @@ -151,7 +151,7 @@ int __init dmar_parse_dev_scope(void *start, void *end, int *cnt,
>  			ret = dmar_parse_one_dev_scope(scope,
>  				&(*devices)[index], segment);
>  			if (ret) {
> -				kfree(*devices);
> +				dmar_free_dev_scope(devices, cnt);
>  				return ret;
>  			}
>  			index ++;
> @@ -162,6 +162,17 @@ int __init dmar_parse_dev_scope(void *start, void *end, int *cnt,
>  	return 0;
>  }
>  
> +void dmar_free_dev_scope(struct pci_dev ***devices, int *cnt)
> +{
> +	if (*devices && *cnt) {
> +		while (--*cnt >= 0)
> +			pci_dev_put((*devices)[*cnt]);
> +		kfree(*devices);
> +		*devices = NULL;
> +		*cnt = 0;
> +	}
> +}
> +
>  /**
>   * dmar_parse_one_drhd - parses exactly one DMA remapping hardware definition
>   * structure which uniquely represent one DMA remapping hardware unit
> diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> index b029d1a..8adfce0 100644
> --- a/include/linux/dmar.h
> +++ b/include/linux/dmar.h
> @@ -159,6 +159,7 @@ extern int dmar_parse_one_rmrr(struct acpi_dmar_header *header);
>  extern int dmar_parse_one_atsr(struct acpi_dmar_header *header);
>  extern int dmar_parse_dev_scope(void *start, void *end, int *cnt,
>  				struct pci_dev ***devices, u16 segment);
> +extern void dmar_free_dev_scope(struct pci_dev ***devices, int *cnt);
>  extern int intel_iommu_init(void);
>  #else /* !CONFIG_INTEL_IOMMU: */
>  static inline int intel_iommu_init(void) { return -ENODEV; }
> 


-- 
Thanks!
Yijing

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