From: David Laight <David.Laight@ACULAB.COM>
To: 'Kalle Valo' <kvalo@kernel.org>, Qing Wang <wangqing@vivo.com>
Cc: Maya Erez <merez@codeaurora.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
"wil6210@qti.qualcomm.com" <wil6210@qti.qualcomm.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] net: wireless: ath: use div64_u64() instead of do_div()
Date: Fri, 11 Feb 2022 12:23:32 +0000 [thread overview]
Message-ID: <f552799ea07049829e68ea63668cbcc8@AcuMS.aculab.com> (raw)
In-Reply-To: <877da2c3xf.fsf@tynnyri.adurom.net>
From: Kalle Valo
> Sent: 10 February 2022 12:16
>
> Qing Wang <wangqing@vivo.com> writes:
>
> > From: Wang Qing <wangqing@vivo.com>
> >
> > do_div() does a 64-by-32 division.
> > When the divisor is u64, do_div() truncates it to 32 bits, this means it
> > can test non-zero and be truncated to zero for division.
> >
> > fix do_div.cocci warning:
> > do_div() does a 64-by-32 division, please consider using div64_u64 instead.
> >
> > Signed-off-by: Wang Qing <wangqing@vivo.com>
> > ---
> > drivers/net/wireless/ath/wil6210/debugfs.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/ath/wil6210/debugfs.c b/drivers/net/wireless/ath/wil6210/debugfs.c
> > index 4c944e5..2cee9dd
> > --- a/drivers/net/wireless/ath/wil6210/debugfs.c
> > +++ b/drivers/net/wireless/ath/wil6210/debugfs.c
> > @@ -1766,7 +1766,7 @@ __acquires(&p->tid_rx_lock) __releases(&p->tid_rx_lock)
> > seq_puts(s, "\n");
> > if (!num_packets)
> > continue;
> > - do_div(tx_latency_avg, num_packets);
> > + div64_u64(tx_latency_avg, num_packets);
>
> As you have been pointed out in your other patches, do_div() and
> div64_u64() work differently.
And how long does it take for num_packets to exceed 2^32.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
prev parent reply other threads:[~2022-02-11 12:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 8:39 [PATCH] net: wireless: ath: use div64_u64() instead of do_div() Qing Wang
2022-02-10 6:40 ` Kalle Valo
2022-02-10 12:16 ` Kalle Valo
2022-02-11 12:23 ` David Laight [this message]
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