[PATCH 4.9 16/59] net: cadence: Fix a sleep-in-atomic-context bug in macb_halt_tx()

From: Greg Kroah-Hartman
Date: Mon Oct 08 2018 - 14:39:47 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>

[ Upstream commit 16fe10cf92783ed9ceb182d6ea2b8adf5e8ec1b8 ]

The kernel module may sleep with holding a spinlock.

The function call paths (from bottom to top) in Linux-4.16 are:

[FUNC] usleep_range
drivers/net/ethernet/cadence/macb_main.c, 648:
usleep_range in macb_halt_tx
drivers/net/ethernet/cadence/macb_main.c, 730:
macb_halt_tx in macb_tx_error_task
drivers/net/ethernet/cadence/macb_main.c, 721:
_raw_spin_lock_irqsave in macb_tx_error_task

To fix this bug, usleep_range() is replaced with udelay().

This bug is found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/net/ethernet/cadence/macb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -517,7 +517,7 @@ static int macb_halt_tx(struct macb *bp)
if (!(status & MACB_BIT(TGO)))
return 0;

- usleep_range(10, 250);
+ udelay(250);
} while (time_before(halt_time, timeout));

return -ETIMEDOUT;