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SubjectRe: [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@jp.fujitsu.com>
> CC: "Luck, Tony" <tony.luck@intel.com>
> CC: Rusty Russell <rusty@rustcorp.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.

> }
>
> - num_cpus = cpus_weight(cpu_mask);
> + num_cpus = cpus_weight(*cpu_mask);
>
> if (!num_cpus)
> goto skip_numa_setup;
> @@ -716,8 +716,8 @@ get_target_cpu (unsigned int gsi, int ir
> /* 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 (numa_cpu = first_cpu(*cpu_mask) ; i < cpu_index ; i++)
> + numa_cpu = next_cpu(numa_cpu, *cpu_mask);
>
> if (numa_cpu != NR_CPUS)
> return cpu_physical_id(numa_cpu);
>
>
> --
---
arch/ia64/kernel/iosapic.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

--- linux-2.6-next.orig/arch/ia64/kernel/iosapic.c
+++ linux-2.6-next/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, cpu_online_mask)
+ if (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));

---

One aside, I'm not sure of ia64, but x86_64 keeps only online cpus in the cpumask_of_node_map.
IOW, if a cpu goes offline, it's removed from the map. So the whole and'ing thing above may
be unnecessary.


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