diff options
author | Greg Kurz <groug@kaod.org> | 2019-04-19 18:34:13 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-26 10:13:06 +0300 |
commit | 1848f2fe61937411e47d1719807722d7d5bef074 (patch) | |
tree | 4f86a68badb9fedd276a9769a7aba4ea86558978 | |
parent | aacd6a4ec8e671ccc8008b7ae6181b1223cca946 (diff) | |
download | linux-1848f2fe61937411e47d1719807722d7d5bef074.tar.xz |
powerpc/powernv/npu: Fix reference leak
commit 02c5f5394918b9b47ff4357b1b18335768cd867d upstream.
Since 902bdc57451c, 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: 902bdc57451c ("powerpc/powernv/idoa: Remove unnecessary pcidev from pci_dn")
Cc: stable@vger.kernel.org # v4.16
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | arch/powerpc/platforms/powernv/npu-dma.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c index dc23d9d2a7d9..6309819ee2f4 100644 --- a/arch/powerpc/platforms/powernv/npu-dma.c +++ b/arch/powerpc/platforms/powernv/npu-dma.c @@ -31,9 +31,22 @@ static DEFINE_SPINLOCK(npu_context_lock); static struct pci_dev *get_pci_dev(struct device_node *dn) { struct pci_dn *pdn = PCI_DN(dn); + struct pci_dev *pdev; - return pci_get_domain_bus_and_slot(pci_domain_nr(pdn->phb->bus), + pdev = pci_get_domain_bus_and_slot(pci_domain_nr(pdn->phb->bus), pdn->busno, pdn->devfn); + + /* + * pci_get_domain_bus_and_slot() increased the reference count of + * the PCI device, but callers don't need that actually as the PE + * already holds a reference to the device. Since callers aren't + * aware of the reference count change, call pci_dev_put() now to + * avoid leaks. + */ + if (pdev) + pci_dev_put(pdev); + + return pdev; } /* Given a NPU device get the associated PCI device. */ |