net: fec: use reinit_completion() in mdio accessor functions

Rather than re-initialising the entire completion on every mdio access,
use reinit_completion() which only resets the completion count.  This
avoids possible reinitialisation of the contained spinlock and waitqueue
while they may be in use (eg, mid-completion.)

Such an event could occur if there's a long delay in interrupt handling
causing the mdio accessor to time out, then a second access comes in
while the interrupt handler on a different CPU has called complete().
Another scenario where this has been observed is while locking has
been missing at the phy layer, allowing concurrent attempts to access
the MDIO bus.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 271bb5862346ede352473f0837fb76e0a5ac7163..b349e6f36ea75fa6a471d3c2a37a7bee21d8e59c 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1778,7 +1778,7 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
                return ret;
 
        fep->mii_timeout = 0;
-       init_completion(&fep->mdio_done);
+       reinit_completion(&fep->mdio_done);
 
        /* start a read op */
        writel(FEC_MMFR_ST | FEC_MMFR_OP_READ |
@@ -1817,7 +1817,7 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
                return ret;
 
        fep->mii_timeout = 0;
-       init_completion(&fep->mdio_done);
+       reinit_completion(&fep->mdio_done);
 
        /* start a write op */
        writel(FEC_MMFR_ST | FEC_MMFR_OP_WRITE |