2018-01-25 10:23:03

by Jia-Ju Bai

Subject: [PATCH] ata: sata_mv: Replace mdelay with usleep_range in mv_reset_channel

After checking all possible call chains to mv_reset_channel here,
my tool finds that mv_reset_channel is never called in atomic context,
namely never in an interrupt handler or holding a spinlock.
Thus mdelay can be replaced with usleep_range to avoid busy wait.

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/ata/sata_mv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index cc208b7..42d4589 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -3596,7 +3596,7 @@ static void mv_reset_channel(struct mv_host_priv *hpriv, void __iomem *mmio,
hpriv->ops->phy_errata(hpriv, mmio, port_no);

if (IS_GEN_I(hpriv))
- mdelay(1);
+ usleep_range(500, 1000);
}

static void mv_pmp_select(struct ata_port *ap, int pmp)
--
1.7.9.5

2018-01-25 15:33:18

by Tejun Heo

Subject: Re: [PATCH] ata: sata_mv: Replace mdelay with usleep_range in mv_reset_channel

On Thu, Jan 25, 2018 at 06:26:52PM +0800, Jia-Ju Bai wrote:
> After checking all possible call chains to mv_reset_channel here,
> my tool finds that mv_reset_channel is never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with usleep_range to avoid busy wait.
>
> This is found by a static analysis tool named DCNS written by myself.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>

Applied to libata/for-4.16.

Thanks.

--
tejun