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Date: Thu, 11 Dec 2008 13:53:09 +0900 (JST)
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: Mike Travis <travis@....com>
Cc: kosaki.motohiro@...fujitsu.com, "Luck, Tony" <tony.luck@...el.com>,
Rusty Russell <rusty@...tcorp.com.au>,
linux-next@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [linux-next][PATCH] cpumask:cpumask_of_node-ia64 fix
> KOSAKI Motohiro wrote:
> > ===
> > Subject: [PATCH] cpumask:cpumask_of_node-ia64 fix
> > Impact: bug fix
> >
> > commit 07c636deede53ff3e96d54df0ece2c838e61951f introduce new CPU mask API and change cpu_mask variable type.
> >
> > -----------------------------------------------
> > - cpumask_t cpu_mask;
> > + const struct cpumask *cpu_mask;
> > --------------------------------------------------
> >
> >
> > However, its change is incomplete. in build time, compiler output following type mismatch warnings.
> >
> > arch/ia64/kernel/iosapic.c:708: warning: passing argument 2 of '__cpu_clear' from incompatible pointer type
> > arch/ia64/kernel/iosapic.c:711: warning: passing argument 1 of '__cpus_weight' from incompatible pointer type
> > arch/ia64/kernel/iosapic.c:719: warning: passing argument 1 of '__first_cpu' from incompatible pointer type
> > arch/ia64/kernel/iosapic.c:720: warning: passing argument 2 of '__next_cpu' from incompatible pointer type
>
> Good catch, however ...
> >
> >
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> > CC: "Luck, Tony" <tony.luck@...el.com>
> > CC: Rusty Russell <rusty@...tcorp.com.au>
> > ---
> > arch/ia64/kernel/iosapic.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > Index: b/arch/ia64/kernel/iosapic.c
> > ===================================================================
> > --- a/arch/ia64/kernel/iosapic.c
> > +++ b/arch/ia64/kernel/iosapic.c
> > @@ -695,7 +695,7 @@ get_target_cpu (unsigned int gsi, int ir
> > #ifdef CONFIG_NUMA
> > {
> > int num_cpus, cpu_index, iosapic_index, numa_cpu, i = 0;
> > - const struct cpumask *cpu_mask;
> > + struct cpumask *cpu_mask;
> >
> > iosapic_index = find_iosapic(gsi);
> > if (iosapic_index < 0 ||
> > @@ -705,10 +705,10 @@ get_target_cpu (unsigned int gsi, int ir
> > cpu_mask = cpumask_of_node(iosapic_lists[iosapic_index].node);
> > for_each_cpu_and(numa_cpu, cpu_mask, &domain) {
> > if (!cpu_online(numa_cpu))
> > - cpu_clear(numa_cpu, cpu_mask);
> > + cpu_clear(numa_cpu, *cpu_mask);
>
> ... you cannot modify the read-only cpumask_of_node map. Suggested alternative below.
Oh, I see.
I didn't understand original intention.
and my review and test doen't find any problem in your patch.
Very thanks.
The following is the folded patch of your patch and your over-simplified fix.
===
Subject: [PATCH] don't change cpumask_of_node
Impact: bug fix
commit 07c636deede53ff3e96d54df0ece2c838e61951f introduce new CPU mask API and change cpu_mask variable type.
However, its change is incomplete. in build time, compiler output following type mismatch warnings.
arch/ia64/kernel/iosapic.c:708: warning: passing argument 2 of '__cpu_clear' from incompatible pointer type
arch/ia64/kernel/iosapic.c:711: warning: passing argument 1 of '__cpus_weight' from incompatible pointer type
arch/ia64/kernel/iosapic.c:719: warning: passing argument 1 of '__first_cpu' from incompatible pointer type
arch/ia64/kernel/iosapic.c:720: warning: passing argument 2 of '__next_cpu' from incompatible pointer type
More unfortunately, current code change the return value o cpumask_of_node().
but it is unacceptable operation. it cause to corrupt data structure.
Signed-off-by: Mike Travis <travis@....com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
CC: "Luck, Tony" <tony.luck@...el.com>
CC: Rusty Russell <rusty@...tcorp.com.au>
---
arch/ia64/kernel/iosapic.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
Index: b/arch/ia64/kernel/iosapic.c
===================================================================
--- a/arch/ia64/kernel/iosapic.c
+++ b/arch/ia64/kernel/iosapic.c
@@ -703,23 +703,23 @@ get_target_cpu (unsigned int gsi, int ir
goto skip_numa_setup;
cpu_mask = cpumask_of_node(iosapic_lists[iosapic_index].node);
+ num_cpus = 0;
for_each_cpu_and(numa_cpu, cpu_mask, &domain) {
- if (!cpu_online(numa_cpu))
- cpu_clear(numa_cpu, cpu_mask);
+ if (cpu_online(numa_cpu))
+ num_cpus++;
}
- num_cpus = cpus_weight(cpu_mask);
-
if (!num_cpus)
goto skip_numa_setup;
/* Use irq assignment to distribute across cpus in node */
cpu_index = irq % num_cpus;
- for (numa_cpu = first_cpu(cpu_mask) ; i < cpu_index ; i++)
- numa_cpu = next_cpu(numa_cpu, cpu_mask);
+ for_each_cpu_and(numa_cpu, cpu_mask, &domain)
+ if (cpu_online(numa_cpu) && i++ >= cpu_index)
+ break;
- if (numa_cpu != NR_CPUS)
+ if (numa_cpu < nr_cpu_ids)
return cpu_physical_id(numa_cpu);
}
skip_numa_setup:
@@ -730,7 +730,7 @@ skip_numa_setup:
* case of NUMA.)
*/
do {
- if (++cpu >= NR_CPUS)
+ if (++cpu >= nr_cpu_ids)
cpu = 0;
} while (!cpu_online(cpu) || !cpu_isset(cpu, domain));
--
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