Arnd Hannemann schrieb:
> Pavel Roskin schrieb:
>> On Mon, 2009-08-24 at 10:57 -0700, Joe Perches wrote:
>>> On Mon, 2009-08-24 at 19:42 +0200, Arnd Hannemann wrote:
>>>> An integer overflow in the minstrel debug code prevented the
>>>> throughput to be displayed correctly. This patch fixes that,
>>>> by swaping the division and multiplication.
>>>>
>>>> Signed-off-by: Arnd Hannemann <hannemann@xxxxxxxxxxxxxxxxxxx>
>>>> ---
>>>> net/mac80211/rc80211_minstrel_debugfs.c | 2 +-
>>>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>>>
>>>> diff --git a/net/mac80211/rc80211_minstrel_debugfs.c b/net/mac80211/rc80211_minstrel_debugfs.c
>>>> index 98f4807..caf9453 100644
>>>> --- a/net/mac80211/rc80211_minstrel_debugfs.c
>>>> +++ b/net/mac80211/rc80211_minstrel_debugfs.c
>>>> @@ -83,7 +83,7 @@ minstrel_stats_open(struct inode *inode, struct file *file)
>>>> p += sprintf(p, "%3u%s", mr->bitrate / 2,
>>>> (mr->bitrate & 1 ? ".5" : " "));
>>>>
>>>> - tp = ((mr->cur_tp * 96) / 18000) >> 10;
>>>> + tp = ((mr->cur_tp / 18000) * 96) >> 10;
>>> Maybe do_div instead?
>> How about this?
>>
>> tp = mr->cur_tp / ((18000 << 10) / 96);
>>
>> ((18000 << 10) / 96) is exactly 192000.
>>
>
> Hmm don't seems to be equivalent with the original statement:
>
> a = 61027734;
> b = ((a * 96) / 18000) >> 10;
> c = a / ((18000 << 10) / 96);
> printf("%u %u\n", b, c);
>
> Outputs:
> 84 317
Outch, sorry I took the overflowing formula not the fixed one!
Best regards,
Arnd
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