[PATCH 1/2] net: axienet: recheck condition after timeout in mdio_wait()
From: kurt@linutronix.de (Kurt Kanzenbach)
Date: 2018-10-30 09:31:53
Also in:
lkml, netdev
Subsystem:
networking drivers, the rest, xilinx axi ethernet driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Radhey Shyam Pandey
The function could report a false positive if it gets preempted between reading the XAE_MDIO_MCR_OFFSET register and checking for the timeout. In such a case, the condition has to be rechecked to avoid false positives. Therefore, check for expected condition even after the timeout occurred. Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de> --- drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
index 757a3b37ae8a..4f13125e4942 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c@@ -21,15 +21,26 @@ int axienet_mdio_wait_until_ready(struct axienet_local *lp) { unsigned long end = jiffies + 2; - while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) & - XAE_MDIO_MCR_READY_MASK)) { + u32 val; + + while (1) { + val = axienet_ior(lp, XAE_MDIO_MCR_OFFSET); + + if (val & XAE_MDIO_MCR_READY_MASK) + return 0; + if (time_before_eq(end, jiffies)) { - WARN_ON(1); - return -ETIMEDOUT; + val = axienet_ior(lp, XAE_MDIO_MCR_OFFSET); + break; } + udelay(1); } - return 0; + if (val & XAE_MDIO_MCR_READY_MASK) + return 0; + + WARN_ON(1); + return -ETIMEDOUT; } /**
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2.11.0