From: "David E. Box" <david.e.box@linux.intel.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: lee.jones@linaro.org, hdegoede@redhat.com,
mgross@linux.intel.com, bhelgaas@google.com,
andriy.shevchenko@linux.intel.com, srinivas.pandruvada@intel.com,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
platform-driver-x86@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH 5/5] platform/x86: Add Intel Software Defined Silicon driver
Date: Fri, 01 Oct 2021 03:38:23 -0700 [thread overview]
Message-ID: <d988a4b8698b20a151680cc98a6b7434efbaea55.camel@linux.intel.com> (raw)
In-Reply-To: <YVa1aiTqS6Ik5cO1@kroah.com>
On Fri, 2021-10-01 at 09:14 +0200, Greg KH wrote:
> On Thu, Sep 30, 2021 at 06:28:15PM -0700, David E. Box wrote:
> > +static int sdsi_device_open(struct inode *inode, struct file *file)
> > +{
> > + struct miscdevice *miscdev = file->private_data;
> > +
> > + get_device(miscdev->this_device);
>
> Why do you think this is needed? Shouldn't the misc core handle all of
> this for you already?
>
> > +
> > + return 0;
> > +}
> > +
> > +static int sdsi_device_release(struct inode *inode, struct file *file)
> > +{
> > +
> > + struct miscdevice *miscdev = file->private_data;
> > + struct sdsi_priv *priv = to_sdsi_priv(miscdev);
> > +
> > + if (priv->akc_owner == file)
> > + priv->akc_owner = NULL;
>
> Why is this needed?
>
> > +
> > + put_device(miscdev->this_device);
>
> I see this matches the open call, but if you do not have this in the
> open call, is it needed here as well?
>
> > + ret = devm_add_action_or_reset(priv->miscdev.this_device, sdsi_miscdev_remove, priv);
> > + if (ret)
> > + goto deregister_misc;
>
> I think this is all you need to clean up your device memory, not the
> get/put device in open/release, right?
It does clean up the memory, but it does so immediately after the device has been unregistered, even
if a file is open. The get/put ensures that if files are open, the memory isn't cleaned up until the
files are closed.
I can show that this happens without the get/put,
open()
unbind device -> devm action called -> kfree(priv)
ioctl() -> priv accessed
but it doesn't blow up. I guess because the former location of priv is accessible by container_of on
the miscdev. But that memory was freed right?
David
>
> thanks,
>
> greg k-h
next prev parent reply other threads:[~2021-10-01 10:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-01 1:28 [PATCH 0/5] Move intel_pm from MFD to Auxiliary bus David E. Box
2021-10-01 1:28 ` [PATCH 1/5] PCI: Add #defines for accessing PCIe DVSEC fields David E. Box
2021-10-01 1:28 ` [PATCH 2/5] platform/x86/intel: Move intel_pmt from MFD to Auxiliary Bus David E. Box
2021-10-06 8:58 ` Leon Romanovsky
2021-10-06 20:58 ` David E. Box
2021-10-10 6:59 ` Leon Romanovsky
2021-11-14 1:56 ` kernel test robot
2021-10-01 1:28 ` [PATCH 3/5] platform/x86/intel: extended_caps: Add support for PCIe VSEC structures David E. Box
2021-10-01 1:28 ` [PATCH 4/5] Documentation: Update ioctl-number.rst for Intel Software Defined Silicon interface David E. Box
2021-10-01 1:28 ` [PATCH 5/5] platform/x86: Add Intel Software Defined Silicon driver David E. Box
2021-10-01 7:14 ` Greg KH
2021-10-01 10:38 ` David E. Box [this message]
2021-10-01 11:29 ` Greg KH
2021-10-01 7:15 ` Greg KH
2021-10-01 7:16 ` Greg KH
2021-10-01 10:47 ` David E. Box
2021-10-01 11:27 ` Greg KH
2021-10-01 7:29 ` Greg KH
2021-10-01 11:13 ` David E. Box
2021-10-01 11:26 ` Greg KH
2021-10-01 20:43 ` David E. Box
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