2011-08-25 21:47:48

by Christian Lamparter

Subject: [PATCH] p54: Use do_div for 64-bit division to fix 32-bit kernels

Use the do_div macro for 64-bit division. Otherwise, the module will
reference __udivdi3 under 32-bit kernels, which is not allowed in
kernel space.

Signed-off-by: Christian Lamparter <[email protected]>
---
diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index 44a3bd4..9865881 100644
--- a/drivers/net/wireless/p54/txrx.c
+++ b/drivers/net/wireless/p54/txrx.c
@@ -19,6 +19,7 @@
#include <linux/init.h>
#include <linux/firmware.h>
#include <linux/etherdevice.h>
+#include <asm/div64.h>

#include <net/mac80211.h>

@@ -582,10 +583,13 @@ static void p54_rx_stats(struct p54_common *priv, struct sk_buff *skb)
if (chan) {
struct survey_info *survey = &priv->survey[chan->hw_value];
survey->noise = clamp_t(s8, priv->noise, -128, 127);
- survey->channel_time = priv->survey_raw.active / 1024;
- survey->channel_time_tx = priv->survey_raw.tx / 1024;
- survey->channel_time_busy = priv->survey_raw.cca / 1024 +
- survey->channel_time_tx;
+ survey->channel_time = priv->survey_raw.active;
+ survey->channel_time_tx = priv->survey_raw.tx;
+ survey->channel_time_busy = priv->survey_raw.tx +
+ priv->survey_raw.cca;
+ do_div(survey->channel_time, 1024);
+ do_div(survey->channel_time_tx, 1024);
+ do_div(survey->channel_time_busy, 1024);
}

tmp = p54_find_and_unlink_skb(priv, hdr->req_id);

2011-09-07 04:27:16

by Calvin Walton

Subject: Re: [PATCH] p54: Use do_div for 64-bit division to fix 32-bit kernels

On Thu, 2011-08-25 at 23:47 +0200, Christian Lamparter wrote:
> Use the do_div macro for 64-bit division. Otherwise, the module will
> reference __udivdi3 under 32-bit kernels, which is not allowed in
> kernel space.
>
> Signed-off-by: Christian Lamparter <[email protected]>
> ---
> diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c

> + do_div(survey->channel_time, 1024);
> + do_div(survey->channel_time_tx, 1024);
> + do_div(survey->channel_time_busy, 1024);

You're doing a division by a power of two here, why not just use a
bit-shift operation ">> 10" instead of a full division operation?

--
Calvin Walton <[email protected]>