| Message ID | 1502778786-14738-1-git-send-email-yanjun.zhu@oracle.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Tue, Aug 15, 2017 at 02:33:05AM -0400, Zhu Yanjun wrote: > The driver core clears the driver data to NULL after device_release > or on probe failure. Thus, it is not necessary to manually clear the > device driver data to NULL. > It makes sense and I'm pretty sure that you are right, but I'm failing to find the function in device core which sets it to NULL. Can you help me and present the actual call stack to that code place? Thanks,
On Tue, Aug 15, 2017 at 10:13:36AM +0300, Leon Romanovsky wrote: > On Tue, Aug 15, 2017 at 02:33:05AM -0400, Zhu Yanjun wrote: > > The driver core clears the driver data to NULL after device_release > > or on probe failure. Thus, it is not necessary to manually clear the > > device driver data to NULL. > > > > It makes sense and I'm pretty sure that you are right, but I'm failing > to find the function in device core which sets it to NULL. Can you help > me and present the actual call stack to that code place? http://elixir.free-electrons.com/linux/v4.13-rc1/source/drivers/base/dd.c#L840 The call to the remove callback is on line 833. This is done after dropping devres, so you could allocate the drv data inside a devm object and everything would unwind correctly. In this case, the kfree is explicit, so I would advocate for still putting the null near the kfree to minimize the time where a free'd pointer is present - eg incase a devm callback or some other bug accidently touches it. Jason
On Tue, Aug 15, 2017 at 11:21:49AM -0600, Jason Gunthorpe wrote: > On Tue, Aug 15, 2017 at 10:13:36AM +0300, Leon Romanovsky wrote: > > On Tue, Aug 15, 2017 at 02:33:05AM -0400, Zhu Yanjun wrote: > > > The driver core clears the driver data to NULL after device_release > > > or on probe failure. Thus, it is not necessary to manually clear the > > > device driver data to NULL. > > > > > > > It makes sense and I'm pretty sure that you are right, but I'm failing > > to find the function in device core which sets it to NULL. Can you help > > me and present the actual call stack to that code place? > > http://elixir.free-electrons.com/linux/v4.13-rc1/source/drivers/base/dd.c#L840 > > The call to the remove callback is on line 833. > > This is done after dropping devres, so you could allocate the drv data > inside a devm object and everything would unwind correctly. Thanks for the pointer. Will it be called in case of failure during initialization too? > > In this case, the kfree is explicit, so I would advocate for still putting > the null near the kfree to minimize the time where a free'd pointer is > present - eg incase a devm callback or some other bug accidently > touches it. > > Jason
From: Zhu Yanjun <yanjun.zhu@oracle.com> Date: Tue, 15 Aug 2017 02:33:05 -0400 > The driver core clears the driver data to NULL after device_release > or on probe failure. Thus, it is not necessary to manually clear the > device driver data to NULL. > > Cc: Joe Jin <joe.jin@oracle.com> > Cc: Junxiao Bi <junxiao.bi@oracle.com> > Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com> Applied.
diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c index 09b9bc1..df9b0ef 100644 --- a/drivers/net/ethernet/mellanox/mlx4/main.c +++ b/drivers/net/ethernet/mellanox/mlx4/main.c @@ -3782,7 +3782,6 @@ static int __mlx4_init_one(struct pci_dev *pdev, int pci_dev_data, err_disable_pdev: mlx4_pci_disable_device(&priv->dev); - pci_set_drvdata(pdev, NULL); return err; } @@ -3997,7 +3996,6 @@ static void mlx4_remove_one(struct pci_dev *pdev) devlink_unregister(devlink); kfree(dev->persist); devlink_free(devlink); - pci_set_drvdata(pdev, NULL); } static int restore_current_port_types(struct mlx4_dev *dev,
The driver core clears the driver data to NULL after device_release or on probe failure. Thus, it is not necessary to manually clear the device driver data to NULL. Cc: Joe Jin <joe.jin@oracle.com> Cc: Junxiao Bi <junxiao.bi@oracle.com> Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com> --- drivers/net/ethernet/mellanox/mlx4/main.c | 2 -- 1 file changed, 2 deletions(-)