On Fri, Nov 30, 2012 at 12:12:46PM +0100, Tux9 wrote:
> I like Vitalii's solution more. Hans's solution assign the value
> -ENOMEM to ret in every round of the loop, which is a kind of wasting
> CPU cycles.
The difference between
1 files changed, 12 insertions(+), 4 deletions(-) and
1 files changed, 2 insertions(+), 0 deletions(-)
is more important. Note that this code is not in a fast path but only
called once at device creation.
Thanks,
Hans
>
> On Fri, Nov 30, 2012 at 12:58 AM, Hans J. Koch <h...@hansjkoch.de> wrote:
> > On Thu, Nov 29, 2012 at 06:36:59PM +0200, Vitalii Demianets wrote:
> >> > On Thursday 29 November 2012 18:05:27 Tux9 wrote:
> >> > > Hans, I think there are something wrong in your patch, while Vitalii's
> >> > > is right. The variable "ret" is reused in line 292 and line 295, so
> >> > > the value of "ret" would be overridden (if it goto err_map in line 284
> >> > > when mi>=1).
> >> >
> >> > Actually, both patches do exactly the same thing. Hans's patch
> >> > establishes
> >> > default value for the ret for all those "other" cases when ret is not
> >> > explicitly overridden. My patch explicitly enumerates all those "other"
> >> > cases in more wordily manner.
> >> >
> >>
> >> Oops, disregard this. After looking at it more thoroughly I got your point.
> >> You are right, ret is overridden at first iteration (mi == 0), so Hans's
> >> approach does not work.
> >> I must do more thinking before replying in a hurry.
> >
> > You're right. Initialization of "ret" has to take place at the beginning of
> > the loop.
> >
> > I think this version is right:
> >
> >
> > From 00c3c734c0dde67873a628bcb18cee403c95c301 Mon Sep 17 00:00:00 2001
> > From: "Hans J. Koch" <h...@hansjkoch.de>
> > Date: Fri, 30 Nov 2012 00:51:50 +0100
> > Subject: [PATCH] uio: Fix warning: 'ret' might be used uninitialized
> >
> > In two cases, the return value variable "ret" can be undefined.
> >
> > Signed-off-by: Hans J. Koch <h...@hansjkoch.de>
> > ---
> > drivers/uio/uio.c | 2 ++
> > 1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> > index 5110f36..0c80df2 100644
> > --- a/drivers/uio/uio.c
> > +++ b/drivers/uio/uio.c
> > @@ -273,6 +273,7 @@ static int uio_dev_add_attributes(struct uio_device
> > *idev)
> > struct uio_portio *portio;
> >
> > for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
> > + ret = -ENOMEM;
> > mem = &idev->info->mem[mi];
> > if (mem->size == 0)
> > break;
> > @@ -298,6 +299,7 @@ static int uio_dev_add_attributes(struct uio_device
> > *idev)
> > }
> >
> > for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
> > + ret = -ENOMEM;
> > port = &idev->info->port[pi];
> > if (port->size == 0)
> > break;
> > --
> > 1.7.9
> >
> > --
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