From 2925c2fdf1e0eb642482f5b30577e9435aaa8edb Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Tue, 15 Sep 2015 15:04:07 +1000 Subject: cxl: Fix unbalanced pci_dev_get in cxl_probe Currently the first thing we do in cxl_probe is to grab a reference on the pci device. Later on, we call device_register on our adapter. In our remove path, we call device_unregister, but we never call pci_dev_put. We therefore leak the device every time we do a reflash. device_register/unregister is sufficient to hold the reference. Therefore, drop the call to pci_dev_get. Here's why this is safe. The proposed cxl_probe(pdev) calls cxl_adapter_init: a) init calls cxl_adapter_alloc, which creates a struct cxl, conventionally called adapter. This struct contains a device entry, adapter->dev. b) init calls cxl_configure_adapter, where we set adapter->dev.parent = &dev->dev (here dev is the pci dev) So at this point, the cxl adapter's device's parent is the PCI device that I want to be refcounted properly. c) init calls cxl_register_adapter *) cxl_register_adapter calls device_register(&adapter->dev) So now we're in device_register, where dev is the adapter device, and we want to know if the PCI device is safe after we return. device_register(&adapter->dev) calls device_initialize() and then device_add(). device_add() does a get_device(). device_add() also explicitly grabs the device's parent, and calls get_device() on it: parent = get_device(dev->parent); So therefore, device_register() takes a lock on the parent PCI dev, which is what pci_dev_get() was guarding. pci_dev_get() can therefore be safely removed. Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards for userspace access") Cc: stable@vger.kernel.org Signed-off-by: Daniel Axtens Acked-by: Ian Munsie Signed-off-by: Michael Ellerman --- drivers/misc/cxl/pci.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers') diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c index 02c85160bfe9..a5e977192b61 100644 --- a/drivers/misc/cxl/pci.c +++ b/drivers/misc/cxl/pci.c @@ -1249,8 +1249,6 @@ static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id) int slice; int rc; - pci_dev_get(dev); - if (cxl_verbose) dump_cxl_config_space(dev); -- cgit v1.2.3-59-g8ed1b