net: enetc: teardown CBDR during PF/VF unbind

Michael reports that after the blamed patch, unbinding a VF would cause
these transactions to remain pending, and trigger some warnings with the
DMA API debug:

$ echo 1 > /sys/bus/pci/devices/0000\:00\:00.0/sriov_numvfs
pci 0000:00:01.0: [1957:ef00] type 00 class 0x020001
fsl_enetc_vf 0000:00:01.0: Adding to iommu group 19
fsl_enetc_vf 0000:00:01.0: enabling device (0000 -> 0002)
fsl_enetc_vf 0000:00:01.0 eno0vf0: renamed from eth0

$ echo 0 > /sys/bus/pci/devices/0000\:00\:00.0/sriov_numvfs
DMA-API: pci 0000:00:01.0: device driver has pending DMA allocations while released from device [count=1]
One of leaked entries details: [size=2048 bytes] [mapped with DMA_BIDIRECTIONAL] [mapped as coherent]
WARNING: CPU: 0 PID: 2547 at kernel/dma/debug.c:853 dma_debug_device_change+0x174/0x1c8
(...)
Call trace:
 dma_debug_device_change+0x174/0x1c8
 blocking_notifier_call_chain+0x74/0xa8
 device_release_driver_internal+0x18c/0x1f0
 device_release_driver+0x20/0x30
 pci_stop_bus_device+0x8c/0xe8
 pci_stop_and_remove_bus_device+0x20/0x38
 pci_iov_remove_virtfn+0xb8/0x128
 sriov_disable+0x3c/0x110
 pci_disable_sriov+0x24/0x30
 enetc_sriov_configure+0x4c/0x108
 sriov_numvfs_store+0x11c/0x198
(...)
DMA-API: Mapped at:
 dma_entry_alloc+0xa4/0x130
 debug_dma_alloc_coherent+0xbc/0x138
 dma_alloc_attrs+0xa4/0x108
 enetc_setup_cbdr+0x4c/0x1d0
 enetc_vf_probe+0x11c/0x250
pci 0000:00:01.0: Removing from iommu group 19

This happens because stupid me moved enetc_teardown_cbdr outside of
enetc_free_si_resources, but did not bother to keep calling
enetc_teardown_cbdr from all the places where enetc_free_si_resources
was called. In particular, now it is no longer called from the main
unbind function, just from the probe error path.

Fixes: 4b47c0b8 ("net: enetc: don't initialize unused ports from a separate code path")
Reported-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/enetc/enetc_pf.c

@@ -1225,6 +1225,7 @@ static void enetc_pf_remove(struct pci_dev *pdev)
 	enetc_free_msix(priv);
 
 	enetc_free_si_resources(priv);
+	enetc_teardown_cbdr(&si->cbd_ring);
 
 	free_netdev(si->ndev);
 

drivers/net/ethernet/freescale/enetc/enetc_vf.c

@@ -223,6 +223,7 @@ static void enetc_vf_remove(struct pci_dev *pdev)
 	enetc_free_msix(priv);
 
 	enetc_free_si_resources(priv);
+	enetc_teardown_cbdr(&si->cbd_ring);
 
 	free_netdev(si->ndev);