[PATCH v4 1/5] sparc/srmmu: Remove on-stack cpumask var

From: Dawei Li
Date: Tue Apr 23 2024 - 22:57:51 EST


In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.

Use cpumask_any_but() to avoid the need for a temporary cpumask on
the stack and simplify code.

Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Signed-off-by: Dawei Li <dawei.li@xxxxxxxxxxxx>
---
arch/sparc/mm/srmmu.c | 40 ++++++++++++----------------------------
1 file changed, 12 insertions(+), 28 deletions(-)

diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index 852085ada368..9df51a62333d 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -1653,13 +1653,15 @@ static void smp_flush_tlb_all(void)
local_ops->tlb_all();
}

+static bool any_other_mm_cpus(struct mm_struct *mm)
+{
+ return cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids;
+}
+
static void smp_flush_cache_mm(struct mm_struct *mm)
{
if (mm->context != NO_CONTEXT) {
- cpumask_t cpu_mask;
- cpumask_copy(&cpu_mask, mm_cpumask(mm));
- cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
- if (!cpumask_empty(&cpu_mask))
+ if (any_other_mm_cpus(mm))
xc1(local_ops->cache_mm, (unsigned long)mm);
local_ops->cache_mm(mm);
}
@@ -1668,10 +1670,7 @@ static void smp_flush_cache_mm(struct mm_struct *mm)
static void smp_flush_tlb_mm(struct mm_struct *mm)
{
if (mm->context != NO_CONTEXT) {
- cpumask_t cpu_mask;
- cpumask_copy(&cpu_mask, mm_cpumask(mm));
- cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
- if (!cpumask_empty(&cpu_mask)) {
+ if (any_other_mm_cpus(mm)) {
xc1(local_ops->tlb_mm, (unsigned long)mm);
if (atomic_read(&mm->mm_users) == 1 && current->active_mm == mm)
cpumask_copy(mm_cpumask(mm),
@@ -1688,10 +1687,7 @@ static void smp_flush_cache_range(struct vm_area_struct *vma,
struct mm_struct *mm = vma->vm_mm;

if (mm->context != NO_CONTEXT) {
- cpumask_t cpu_mask;
- cpumask_copy(&cpu_mask, mm_cpumask(mm));
- cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
- if (!cpumask_empty(&cpu_mask))
+ if (any_other_mm_cpus(mm))
xc3(local_ops->cache_range, (unsigned long)vma, start,
end);
local_ops->cache_range(vma, start, end);
@@ -1705,10 +1701,7 @@ static void smp_flush_tlb_range(struct vm_area_struct *vma,
struct mm_struct *mm = vma->vm_mm;

if (mm->context != NO_CONTEXT) {
- cpumask_t cpu_mask;
- cpumask_copy(&cpu_mask, mm_cpumask(mm));
- cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
- if (!cpumask_empty(&cpu_mask))
+ if (any_other_mm_cpus(mm))
xc3(local_ops->tlb_range, (unsigned long)vma, start,
end);
local_ops->tlb_range(vma, start, end);
@@ -1720,10 +1713,7 @@ static void smp_flush_cache_page(struct vm_area_struct *vma, unsigned long page)
struct mm_struct *mm = vma->vm_mm;

if (mm->context != NO_CONTEXT) {
- cpumask_t cpu_mask;
- cpumask_copy(&cpu_mask, mm_cpumask(mm));
- cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
- if (!cpumask_empty(&cpu_mask))
+ if (any_other_mm_cpus(mm))
xc2(local_ops->cache_page, (unsigned long)vma, page);
local_ops->cache_page(vma, page);
}
@@ -1734,10 +1724,7 @@ static void smp_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
struct mm_struct *mm = vma->vm_mm;

if (mm->context != NO_CONTEXT) {
- cpumask_t cpu_mask;
- cpumask_copy(&cpu_mask, mm_cpumask(mm));
- cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
- if (!cpumask_empty(&cpu_mask))
+ if (any_other_mm_cpus(mm))
xc2(local_ops->tlb_page, (unsigned long)vma, page);
local_ops->tlb_page(vma, page);
}
@@ -1759,10 +1746,7 @@ static void smp_flush_page_to_ram(unsigned long page)

static void smp_flush_sig_insns(struct mm_struct *mm, unsigned long insn_addr)
{
- cpumask_t cpu_mask;
- cpumask_copy(&cpu_mask, mm_cpumask(mm));
- cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
- if (!cpumask_empty(&cpu_mask))
+ if (any_other_mm_cpus(mm))
xc2(local_ops->sig_insns, (unsigned long)mm, insn_addr);
local_ops->sig_insns(mm, insn_addr);
}
--
2.27.0