From: Joe Perches <joe@perches•com>
To: David Miller <davem@davemloft•net>
Cc: hofrat@osadl•org, samuel@sortiz•org, netdev@vger•kernel.org,
linux-kernel@vger•kernel.org
Subject: Re: [PATCH] irda: irda-usb: use msecs_to_jiffies for conversions
Date: Tue, 19 May 2015 14:09:07 -0700 [thread overview]
Message-ID: <1432069747.2870.215.camel@perches.com> (raw)
In-Reply-To: <20150519.164555.1631069770118420652.davem@davemloft.net>
On Tue, 2015-05-19 at 16:45 -0400, David Miller wrote:
> From: Joe Perches <joe@perches•com>
> Date: Tue, 19 May 2015 07:32:15 -0700
>
> > On Tue, 2015-05-19 at 12:51 +0200, Nicholas Mc Guire wrote:
> >> 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.
> > []
> >> diff --git 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)));
> >
> > The unnecessary () around msecs_to_jiffies could be removed.
The other thing that could be done is to use
max(1ul, msecs_to_jiffies())
so that there's always some delay even if HZ <= 50
next prev parent reply other threads:[~2015-05-19 21:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-19 10:51 [PATCH] irda: irda-usb: use msecs_to_jiffies for conversions Nicholas Mc Guire
2015-05-19 14:32 ` Joe Perches
2015-05-19 20:45 ` David Miller
2015-05-19 21:09 ` Joe Perches [this message]
2015-05-20 1:44 ` Guenter Roeck
2015-05-20 3:57 ` Joe Perches
-- strict thread matches above, loose matches on Subject: below --
2015-05-23 12:46 Nicholas Mc Guire
2015-05-25 21:39 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1432069747.2870.215.camel@perches.com \
--to=joe@perches$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=hofrat@osadl$(echo .)org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=netdev@vger$(echo .)kernel.org \
--cc=samuel@sortiz$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox