On Mon, Nov 27, 2006 at 05:34:33PM +0900, Magnus Damm wrote:
> On Mon, 2006-11-27 at 17:02 +0900, Horms wrote:
> > On Mon, Nov 27, 2006 at 03:51:09PM +0900, Magnus Damm wrote:
> > > kexec-tools: add nr_matched argument to kexec_iomem_for_each_line()
> > >
> > > This patch passes the number of matched lines using a pointer argument
> > > instead of using the return value as suggested by Vivek.
> > >
> > > Signed-off-by: Magnus Damm <[EMAIL PROTECTED]>
> >
> > I have to say that I don't really see the merit of this change. I think
> > its quite ok for functions that process a number of items, (like
> > sprintf()), return the number of items processed. Though I am prepared
> > to put it in anyway. Some more specific coments are below.
>
> I totally agree with you - I don't see the merit either. I think the
> code just becomes messier with this change.
>
> Vivek, what do you think? Do you have a better implementation?
>
> > > ---
> > >
> > > kexec/crashdump-xen.c | 8 +++++---
> > > kexec/kexec-iomem.c | 33 +++++++++++++++++----------------
> > > kexec/kexec.h | 3 ++-
> > > 3 files changed, 24 insertions(+), 20 deletions(-)
> > >
> > > --- 0001/kexec/crashdump-xen.c
> > > +++ work/kexec/crashdump-xen.c 2006-11-27 15:29:09.000000000 +0900
> > > @@ -48,20 +48,22 @@ int xen_get_nr_phys_cpus(void)
> > > if (xen_phys_cpus)
> > > return xen_phys_cpus;
> > >
> > > - if ((cpus = kexec_iomem_for_each_line(match, NULL, NULL))) {
> > > + if (kexec_iomem_for_each_line(match, NULL, NULL, &cpus) == 0) {
> > > n = sizeof(struct crash_note_info) * cpus;
> > > + xen_phys_cpus = cpus;
> > > xen_phys_notes = malloc(n);
> > > if (xen_phys_notes) {
> > > memset(xen_phys_notes, 0, n);
> > > kexec_iomem_for_each_line(match,
> > > xen_crash_note_callback,
> > > + NULL,
> > > NULL);
> > > }
> > >
> > > - xen_phys_cpus = cpus;
> > > + return xen_phys_cpus;
> > > }
> > >
> > > - return cpus;
> > > + return -1;
> > > }
> >
> > I don't think that the above code takes into account the case where
> > cpus is set to < 1 by kexec_iomem_for_each_line().
>
> The nr variable in kexec_iomem_for_each_line() starts counting from 0.
> So it should never set cpus to less than 0.
I was actually most worried about the 0 case. I am guessing that
malloc(0) and memset(x, y, 0), is ok, but it doesn't make me feel very
comfortable.
As for cpus < 0, which doesn't occur, perhaps the prototype of
kexec_iomem_for_each_line() should specify an unsigned int rather than
an int.
>
> > > int xen_get_note(int cpu, uint64_t *addr, uint64_t *len)
> > > --- 0001/kexec/kexec-iomem.c
> > > +++ work/kexec/kexec-iomem.c 2006-11-27 15:30:29.000000000 +0900
> > > @@ -17,7 +17,6 @@
> > > *
> > > * Iterate over each line in /proc/iomem. If match is NULL or if the line
> > > * matches with our match-pattern then call the callback if non-NULL.
> > > - * Return the number of lines matched.
> > > */
> > >
> > > int kexec_iomem_for_each_line(char *match,
> > > @@ -26,7 +25,8 @@ int kexec_iomem_for_each_line(char *matc
> > > char *str,
> > > unsigned long base,
> > > unsigned long length),
> > > - void *data)
> > > + void *data,
> > > + int *nr_matched)
> > > {
> > > const char iomem[]= "/proc/iomem";
> > > char line[MAX_LINE];
> > > @@ -58,7 +58,10 @@ int kexec_iomem_for_each_line(char *matc
> > >
> > > fclose(fp);
> > >
> > > - return nr;
> > > + if (nr_matched)
> > > + *nr_matched = nr;
> > > +
> > > + return 0;
> > > }
> >
> > I notice that if kexec_iomem_for_each_line() returns, it always returns 0.
> > I guess that is ok as it leaves room to return -1 later if the need
> > arises.
>
> Yeah, I did not want to convert the die-call to return -1. I felt it was
> out of the scope for this particular patch.
Agreed.
> > > static int kexec_iomem_single_callback(void *data, int nr,
> > > @@ -79,23 +82,21 @@ static int kexec_iomem_single_callback(v
> > > int parse_iomem_single(char *str, uint64_t *start, uint64_t *end)
> > > {
> > > struct memory_range range;
> > > - int ret;
> > > + int nr;
> > >
> > > memset(&range, 0, sizeof(range));
> > >
> > > - ret = kexec_iomem_for_each_line(str, kexec_iomem_single_callback,
> > > - &range);
> > > + if (kexec_iomem_for_each_line(str, kexec_iomem_single_callback,
> > > + &range, &nr) == 0) {
> > > + if (nr == 1) {
> > > + if (start)
> > > + *start = range.start;
> > > + if (end)
> > > + *end = range.end;
> > >
> > > - if (ret == 1) {
> > > - if (start)
> > > - *start = range.start;
> > > - if (end)
> > > - *end = range.end;
> > > -
> > > - ret = 0;
> > > + return 0;
> > > + }
> > > }
> > > - else
> > > - ret = -1;
> > >
> > > - return ret;
> > > + return -1;
> > > }
> >
> > I think that something like the following is a bit clearer than the
> > fragment above.
> >
> > @@ -79,23 +82,18 @@
> > int parse_iomem_single(char *str, uint64_t *start, uint64_t *end)
> > {
> > struct memory_range range;
> > - int ret;
> > + int nr;
> >
> > memset(&range, 0, sizeof(range));
> >
> > - ret = kexec_iomem_for_each_line(str, kexec_iomem_single_callback,
> > - &range);
> > -
> > - if (ret == 1) {
> > + if (kexec_iomem_for_each_line(str, kexec_iomem_single_callback,
> > + &range, &nr) < 0 || nr != 1) {
>
> Uhm, the code may be clearer but I think you should test for == 0 && nr
> == 1 instead.
Yes, sorry I mucked up my patch a bit.
> > if (start)
> > *start = range.start;
> > if (end)
> > *end = range.end;
> > -
> > - ret = 0;
> > + return 0;
> > }
> > - else
> > - ret = -1;
> >
> > - return ret;
> > + return -1;
> > }
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