Messages in this thread | | | Date | Wed, 28 Oct 2015 14:41:35 +0000 | From | Nicholas Mc Guire <> | Subject | Re: [PATCH 3.12 117/123] [media] gscpa_m5602: use msecs_to_jiffies for conversions |
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On Wed, Oct 28, 2015 at 02:53:48PM +0100, Jiri Slaby wrote: > From: Nicholas Mc Guire <hofrat@osadl.org> > > 3.12-stable review patch. If anyone has any objections, please let me know. > > =============== > > commit 63f2f417526fc54191f2b813f72dc1d5322bede8 upstream. > > API compliance scanning with coccinelle flagged: > ./drivers/media/usb/gspca/m5602/m5602_s5k83a.c:180:9-25: > WARNING: timeout (100) seems HZ dependent > > Numeric constants passed to schedule_timeout() make the effective > timeout HZ dependent which makes little sense in a polling loop for > the cameras rotation state. > Fixed up by converting the constant to jiffies with msecs_to_jiffies() > > Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> > Signed-off-by: Hans de Goede <hdegoede@redhat.com> > Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com> > Cc: Oliver Neukum <ONeukum@suse.com> > Signed-off-by: Jiri Slaby <jslaby@suse.cz> > --- > drivers/media/usb/gspca/m5602/m5602_s5k83a.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/usb/gspca/m5602/m5602_s5k83a.c b/drivers/media/usb/gspca/m5602/m5602_s5k83a.c > index 7cbc3a00bda8..bf6b215438e3 100644 > --- a/drivers/media/usb/gspca/m5602/m5602_s5k83a.c > +++ b/drivers/media/usb/gspca/m5602/m5602_s5k83a.c > @@ -177,7 +177,7 @@ static int rotation_thread_function(void *data) > __s32 vflip, hflip; > > set_current_state(TASK_INTERRUPTIBLE); > - while (!schedule_timeout(100)) { > + while (!schedule_timeout(msecs_to_jiffies(100))) { > if (mutex_lock_interruptible(&sd->gspca_dev.usb_lock)) > break; >
Note that there were some concerns regarding using msecs_to_jiffies rather than explicit conversion where gcc can do constant folding (so in this case something like (100 * HZ / 1000) this was mitigated by the following pathes to kbuild see https://lkml.org/lkml/2015/5/28/524 https://lkml.org/lkml/2015/5/28/525
in this case this does not really apply as the numeric 100 is actually a bug - but there might be some performance concerns if too many such conversions are added (there were all together about 30 such cases).
thx! hofrat
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