powerpc/eeh: atomic_dec_if_positive() to update passthru count

No need to have two atomic opertions (update and fetch/check) when
decreasing PE's number of passed devices as one atomic operation
is enough.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 00ba5de..893978c 100644 (file)
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -1412,8 +1412,7 @@ void eeh_dev_release(struct pci_dev *pdev)
                goto out;
 
        /* Decrease PE's pass through count */
-       atomic_dec(&edev->pe->pass_dev_cnt);
-       WARN_ON(atomic_read(&edev->pe->pass_dev_cnt) < 0);
+       WARN_ON(atomic_dec_if_positive(&edev->pe->pass_dev_cnt) < 0);
        eeh_pe_change_owner(edev->pe);
 out:
        mutex_unlock(&eeh_dev_mutex);