2015-05-23 12:56:26

by Nicholas Mc Guire

Subject: [PATCH] irda: irda-usb: use msecs_to_jiffies for conversions

API compliance scanning with coccinelle flagged:

Converting milliseconds to jiffies by "val * HZ / 1000" is technically
is not a clean solution as it does not handle all corner cases correctly.
By changing the conversion to use msecs_to_jiffies(val) conversion is
correct in all cases.

in the current code:
mod_timer(&self->rx_defer_timer, jiffies + (10 * HZ / 1000));
for HZ < 100 (e.g. CONFIG_HZ == 64|32 in alpha) this effectively results
in no delay at all.

Patch was compile tested for x86_64_defconfig (implies CONFIG_USB_IRDA=m)

Patch is against 4.1-rc4 (localversion-next is -next-20150522)

Signed-off-by: Nicholas Mc Guire <[email protected]>
---

V2: the unnecessary () flagged by Joe Perches <[email protected]>
was removed - thanks (...once again...) !

drivers/net/irda/irda-usb.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/irda/irda-usb.c b/drivers/net/irda/irda-usb.c
index f6c9163..f3e4563 100644
--- a/drivers/net/irda/irda-usb.c
+++ b/drivers/net/irda/irda-usb.c
@@ -848,7 +848,9 @@ static void irda_usb_receive(struct urb *urb)
* Jean II */
self->rx_defer_timer.function = irda_usb_rx_defer_expired;
self->rx_defer_timer.data = (unsigned long) urb;
- mod_timer(&self->rx_defer_timer, jiffies + (10 * HZ / 1000));
+ mod_timer(&self->rx_defer_timer,
+ jiffies + msecs_to_jiffies(10));
+
return;
}

--
1.7.10.4

2015-05-25 21:39:50

by David Miller

Subject: Re: [PATCH] irda: irda-usb: use msecs_to_jiffies for conversions

From: Nicholas Mc Guire <[email protected]>
Date: Sat, 23 May 2015 14:46:30 +0200

> API compliance scanning with coccinelle flagged:
>
> Converting milliseconds to jiffies by "val * HZ / 1000" is technically
> is not a clean solution as it does not handle all corner cases correctly.
> By changing the conversion to use msecs_to_jiffies(val) conversion is
> correct in all cases.
>
> in the current code:
> mod_timer(&self->rx_defer_timer, jiffies + (10 * HZ / 1000));
> for HZ < 100 (e.g. CONFIG_HZ == 64|32 in alpha) this effectively results
> in no delay at all.
>
> Patch was compile tested for x86_64_defconfig (implies CONFIG_USB_IRDA=m)
>
> Patch is against 4.1-rc4 (localversion-next is -next-20150522)
>
> Signed-off-by: Nicholas Mc Guire <[email protected]>

Applied to net-next, thanks.