• Greg Kurz's avatar
    powerpc/powernv/npu: Fix reference leak · 1848f2fe
    Greg Kurz authored
    commit 02c5f539 upstream.
    
    Since 902bdc57, get_pci_dev() calls pci_get_domain_bus_and_slot(). This
    has the effect of incrementing the reference count of the PCI device, as
    explained in drivers/pci/search.c:
    
     * Given a PCI domain, bus, and slot/function number, the desired PCI
     * device is located in the list of PCI devices. If the device is
     * found, its reference count is increased and this function returns a
     * pointer to its data structure.  The caller must decrement the
     * reference count by calling pci_dev_put().  If no device is found,
     * %NULL is returned.
    
    Nothing was done to call pci_dev_put() and the reference count of GPU and
    NPU PCI devices rockets up.
    
    A natural way to fix this would be to teach the callers about the change,
    so that they call pci_dev_put() when done with the pointer. This turns
    out to be quite intrusive, as it affects many paths in npu-dma.c,
    pci-ioda.c and vfio_pci_nvlink2.c. Also, the issue appeared in 4.16 and
    some affected code got moved around since then: it would be problematic
    to backport the fix to stable releases.
    
    All that code never cared for reference counting anyway. Call pci_dev_put()
    from get_pci_dev() to revert to the previous behavior.
    
    Fixes: 902bdc57 ("powerpc/powernv/idoa: Remove unnecessary pcidev from pci_dn")
    Cc: stable@vger.kernel.org # v4.16
    Signed-off-by: default avatarGreg Kurz <groug@kaod.org>
    Reviewed-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    1848f2fe
npu-dma.c 32.5 KB