Re: [PATCH v4 3/4] perf/x86/intel/uncore: Fix reference count leak in snr_uncore_mmio_map()

["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, so snr_uncore_get_mc_dev() will return a pci_dev with its
> reference count increased. We need to call pci_dev_put() to decrease the
> reference count before exiting from snr_uncore_mmio_map(). Add
> pci_dev_put() for both normal and error path.
> 
> Fixes: ee49532b38dd ("perf/x86/intel/uncore: Add IMC uncore support for Snow Ridge")
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
> ---
>  arch/x86/events/intel/uncore_snbep.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index 3fc484045ed6..0481f5135cb1 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -4866,9 +4866,12 @@ static int snr_uncore_mmio_map(struct intel_uncore_box *box,

Similar to the previous comments.
I think we can release the dev immediately once when we do not use it
anymore. So we don't need to patch it everywhere later.

Thanks,
Kan
>  	box->io_addr = ioremap(addr, type->mmio_map_size);
>  	if (!box->io_addr) {
>  		pr_warn("perf uncore: Failed to ioremap for %s.\n", type->name);
> +		pci_dev_put(pdev);
>  		return -EINVAL;
>  	}
>  
> +	pci_dev_put(pdev);
> +
>  	return 0;
>  }
>