[PATCH 2/2] net: xilinx_emaclite: recheck condition after timeout in mdio_wait()
From: Kurt Kanzenbach <kurt@linutronix.de>
Date: 2018-10-30 09:31:58
Also in:
linux-arm-kernel, lkml
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The function could report a false positive if it gets preempted between reading the XEL_MDIOCTRL_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_emaclite.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/xilinx/xilinx_emaclite.c b/drivers/net/ethernet/xilinx/xilinx_emaclite.c
index 639e3e99af46..957d03085bd0 100644
--- a/drivers/net/ethernet/xilinx/xilinx_emaclite.c
+++ b/drivers/net/ethernet/xilinx/xilinx_emaclite.c@@ -714,19 +714,29 @@ static irqreturn_t xemaclite_interrupt(int irq, void *dev_id) static int xemaclite_mdio_wait(struct net_local *lp) { unsigned long end = jiffies + 2; + u32 val; /* wait for the MDIO interface to not be busy or timeout * after some time. */ - while (xemaclite_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET) & - XEL_MDIOCTRL_MDIOSTS_MASK) { + while (1) { + val = xemaclite_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET); + + if (!(val & XEL_MDIOCTRL_MDIOSTS_MASK)) + return 0; + if (time_before_eq(end, jiffies)) { - WARN_ON(1); - return -ETIMEDOUT; + val = xemaclite_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET); + break; } + msleep(1); } - return 0; + if (!(val & XEL_MDIOCTRL_MDIOSTS_MASK)) + return 0; + + WARN_ON(1); + return -ETIMEDOUT; } /**
--
2.11.0