[PATCH v2 0/4] powerpc: A few misc cpumask changes

[PATCH v2 0/4] powerpc: A few misc cpumask changes

[Shrikanth Hegde]

These are some miscellaneous code refactors around using cpumask
APIs. They are mainly aimed at code simplification.

Changes since v1:
- Dropped the changes done in xive_find_target_in_mask. Those changes are
  done by Yury Norov already.
- Collected the tags. Thanks to Yury Norov. 
- Added new patch to use cpumask_intersects instead of using
  temp_mask to achieve the same goal.
- Added new patch to print the warning when target CPU not found
  as discussed in [2]. This patch is kept separate since this adds
  a new warning in case of failure. So one may perceive it as functional
  change.

v1[1]: https://lore.kernel.org/all/20260327063129.127302-1-sshegde@linux.ibm.com/
[2]:   https://lore.kernel.org/all/20260319033647.881246-1-ynorov@nvidia.com/

Based on tip/master at: (dffc5753ba4c "Merge branch into tip/master: 'timers/clocksource'")

Shrikanth Hegde (4):
  powerpc: Use cpumask_next_wrap instead
  powerpc: Simplify cpumask api usage for cpuinfo display
  powerpc/perf: Use cpumask_intersects api for checking disable path
  powerpc/xive: Add warning if target CPU not found

 arch/powerpc/kernel/irq.c             | 5 +----
 arch/powerpc/kernel/setup-common.c    | 7 ++-----
 arch/powerpc/mm/book3s64/hash_utils.c | 4 +---
 arch/powerpc/perf/imc-pmu.c           | 6 ++----
 arch/powerpc/sysdev/xive/common.c     | 1 +
 5 files changed, 7 insertions(+), 16 deletions(-)

-- 
2.47.3

[PATCH v2 1/4] powerpc: Use cpumask_next_wrap instead

[Shrikanth Hegde]

cpu = cpumask_next(cpu, mask)
if (cpu >= nr_cpu_ids)
    cpu = cpumask_first(mask)

Above block is identical to:
cpu = cpumask_next_wrap(cpu, mask)

Replace it, No change in functionality or performance.
Slightly simpler code.

Reviewed-by: Yury Norov <ynorov@nvidia.com>
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
---
 arch/powerpc/kernel/irq.c             | 5 +----
 arch/powerpc/mm/book3s64/hash_utils.c | 4 +---
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index a0e8b998c9b5..f69de08ad347 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -370,10 +370,7 @@ int irq_choose_cpu(const struct cpumask *mask)
 do_round_robin:
 		raw_spin_lock_irqsave(&irq_rover_lock, flags);
 
-		irq_rover = cpumask_next(irq_rover, cpu_online_mask);
-		if (irq_rover >= nr_cpu_ids)
-			irq_rover = cpumask_first(cpu_online_mask);
-
+		irq_rover = cpumask_next_wrap(irq_rover, cpu_online_mask);
 		cpuid = irq_rover;
 
 		raw_spin_unlock_irqrestore(&irq_rover_lock, flags);
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index 9dc5889d6ecb..e4fcf929cb33 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1299,9 +1299,7 @@ static void stress_hpt_timer_fn(struct timer_list *timer)
 	if (!firmware_has_feature(FW_FEATURE_LPAR))
 		tlbiel_all();
 
-	next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
-	if (next_cpu >= nr_cpu_ids)
-		next_cpu = cpumask_first(cpu_online_mask);
+	next_cpu = cpumask_next_wrap(raw_smp_processor_id(), cpu_online_mask);
 	stress_hpt_timer.expires = jiffies + msecs_to_jiffies(10);
 	add_timer_on(&stress_hpt_timer, next_cpu);
 }
-- 
2.47.3

[PATCH v2 2/4] powerpc: Simplify cpumask api usage for cpuinfo display

[Shrikanth Hegde]

- cpumask_next can take -1 as valid argument. So simplify cpuinfo
  iterator.

- Use cpumask_last to find if this_cpu is last online CPU.

/proc/cpuinfo shows same info with patch.

Reviewed-by: Yury Norov <ynorov@nvidia.com>
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
---
 arch/powerpc/kernel/setup-common.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 8a86b0efcb1c..aecabe9cf139 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -323,7 +323,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 	seq_putc(m, '\n');
 
 	/* If this is the last cpu, print the summary */
-	if (cpumask_next(cpu_id, cpu_online_mask) >= nr_cpu_ids)
+	if (cpu_id == cpumask_last(cpu_online_mask))
 		show_cpuinfo_summary(m);
 
 	return 0;
@@ -331,10 +331,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 
 static void *c_start(struct seq_file *m, loff_t *pos)
 {
-	if (*pos == 0)	/* just in case, cpu 0 is not the first */
-		*pos = cpumask_first(cpu_online_mask);
-	else
-		*pos = cpumask_next(*pos - 1, cpu_online_mask);
+	*pos = cpumask_next(*pos - 1, cpu_online_mask);
 	if ((*pos) < nr_cpu_ids)
 		return (void *)(unsigned long)(*pos + 1);
 	return NULL;
-- 
2.47.3

[PATCH v2 3/4] powerpc/perf: Use cpumask_intersects api for checking disable path

[Shrikanth Hegde]

First online CPU in the node disables the nest counters by
making an OPAL call. Any other CPU in that node, will bail out.

Instead of using a temporary mask to find out if any cpu in the
node is visited or not, it is better to use the cpumask_intersects
api to achieve the same.

Similarly a temporary cpumask is used to check if a core is already part
of core_imc_cpumask. Use the same cpumask_intersects api there.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
---
 arch/powerpc/perf/imc-pmu.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index c1563b4eaa94..e3822f36c419 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -421,7 +421,6 @@ static int ppc_nest_imc_cpu_offline(unsigned int cpu)
 static int ppc_nest_imc_cpu_online(unsigned int cpu)
 {
 	const struct cpumask *l_cpumask;
-	static struct cpumask tmp_mask;
 	int res;
 
 	/* Get the cpumask of this node */
@@ -431,7 +430,7 @@ static int ppc_nest_imc_cpu_online(unsigned int cpu)
 	 * If this is not the first online CPU on this node, then
 	 * just return.
 	 */
-	if (cpumask_and(&tmp_mask, l_cpumask, &nest_imc_cpumask))
+	if (cpumask_intersects(l_cpumask, &nest_imc_cpumask))
 		return 0;
 
 	/*
@@ -647,14 +646,13 @@ static bool is_core_imc_mem_inited(int cpu)
 static int ppc_core_imc_cpu_online(unsigned int cpu)
 {
 	const struct cpumask *l_cpumask;
-	static struct cpumask tmp_mask;
 	int ret = 0;
 
 	/* Get the cpumask for this core */
 	l_cpumask = cpu_sibling_mask(cpu);
 
 	/* If a cpu for this core is already set, then, don't do anything */
-	if (cpumask_and(&tmp_mask, l_cpumask, &core_imc_cpumask))
+	if (cpumask_intersects(l_cpumask, &core_imc_cpumask))
 		return 0;
 
 	if (!is_core_imc_mem_inited(cpu)) {
-- 
2.47.3

[PATCH v2 4/4] powerpc/xive: Add warning if target CPU not found

[Shrikanth Hegde]

Add a warn_once to warn if the CPU target is not found. This could help
to find about any such usecase.

This is a very rare case, which either means mask was empty or
atomic update failed for all online CPUs. So it is worth printing that
path for potential fix.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
---
 arch/powerpc/sysdev/xive/common.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index c120be73d149..dadd1f46ec93 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -564,6 +564,7 @@ static int xive_find_target_in_mask(const struct cpumask *mask,
 			return cpu;
 	}
 
+	WARN_ONCE(1, "target CPU not found in mask: %*pbl\n", cpumask_pr_args(mask));
 	return -1;
 }
 
-- 
2.47.3