Re: [PATCH v3] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated

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On 12/14/20 12:07 PM, Greg KH wrote:
On Mon, Dec 14, 2020 at 11:56:17AM -0500, Tony Krowiak wrote:
The vfio_ap device driver registers a group notifier with VFIO when the
file descriptor for a VFIO mediated device for a KVM guest is opened to
receive notification that the KVM pointer is set (VFIO_GROUP_NOTIFY_SET_KVM
event). When the KVM pointer is set, the vfio_ap driver takes the
following actions:
1. Stashes the KVM pointer in the vfio_ap_mdev struct that holds the state
    of the mediated device.
2. Calls the kvm_get_kvm() function to increment its reference counter.
3. Sets the function pointer to the function that handles interception of
    the instruction that enables/disables interrupt processing.
4. Sets the masks in the KVM guest's CRYCB to pass AP resources through to
    the guest.

In order to avoid memory leaks, when the notifier is called to receive
notification that the KVM pointer has been set to NULL, the vfio_ap device
driver should reverse the actions taken when the KVM pointer was set.

Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback")
Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
---
  drivers/s390/crypto/vfio_ap_ops.c | 29 ++++++++++++++++++++---------
  1 file changed, 20 insertions(+), 9 deletions(-)
<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

I read the document on the correct way to submit patches for inclusion in
the stable kernel. I apologize for my ignorance, but I don't see the
problem. Can you help me out here? Does a patch that fixes a memory leak
not qualify or is it something else?





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