Re: [PATCH v4 2/4] perf/x86/intel/uncore: Fix reference count leak in hswep_has_limit_sbox()

["Liang, Kan" <kan.liang@linux.intel.com>]

On 2022-11-17 4:43 a.m., Xiongfeng Wang wrote:
> pci_get_device() will increase the reference count for the returned
> pci_dev. We need to call pci_dev_put() to decrease the reference count
> before exiting from hswep_has_limit_sbox(). Add pci_dev_put() for both
> normal and error path.
> 
> Fixes: 9d480158ee86 ("perf/x86/intel/uncore: Remove uncore extra PCI dev HSWEP_PCI_PCU_3")
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
> ---
>  arch/x86/events/intel/uncore_snbep.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index 76fedc8e12dd..3fc484045ed6 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -2891,8 +2891,12 @@ static bool hswep_has_limit_sbox(unsigned int device)
>  		return false;
>  
>  	pci_read_config_dword(dev, HSWEP_PCU_CAPID4_OFFET, &capid4);

I think we can move the pci_dev_put here to avoid patching it twice.

Thanks,
Kan

> -	if (!hswep_get_chop(capid4))
> +	if (!hswep_get_chop(capid4)) {
> +		pci_dev_put(dev);
>  		return true;
> +	}
> +
> +	pci_dev_put(dev);
>  
>  	return false;
>  }