scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 164 insertions, 0 deletions

diff --git a/drivers/iommu/iommu-debug-pagealloc.c b/drivers/iommu/iommu-debug-pagealloc.c
new file mode 100644
index 000000000..80164df5b
--- /dev/null
+++ b/drivers/iommu/iommu-debug-pagealloc.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2025 - Google Inc
+ * Author: Mostafa Saleh <smostafa@google.com>
+ * IOMMU API debug page alloc sanitizer
+ */
+#include <linux/atomic.h>
+#include <linux/iommu.h>
+#include <linux/iommu-debug-pagealloc.h>
+#include <linux/kernel.h>
+#include <linux/page_ext.h>
+#include <linux/page_owner.h>
+
+#include "iommu-priv.h"
+
+static bool needed;
+DEFINE_STATIC_KEY_FALSE(iommu_debug_initialized);
+
+struct iommu_debug_metadata {
+	atomic_t ref;
+};
+
+static __init bool need_iommu_debug(void)
+{
+	return needed;
+}
+
+struct page_ext_operations page_iommu_debug_ops = {
+	.size = sizeof(struct iommu_debug_metadata),
+	.need = need_iommu_debug,
+};
+
+static struct iommu_debug_metadata *get_iommu_data(struct page_ext *page_ext)
+{
+	return page_ext_data(page_ext, &page_iommu_debug_ops);
+}
+
+static void iommu_debug_inc_page(phys_addr_t phys)
+{
+	struct page_ext *page_ext = page_ext_from_phys(phys);
+	struct iommu_debug_metadata *d;
+
+	if (!page_ext)
+		return;
+
+	d = get_iommu_data(page_ext);
+	WARN_ON(atomic_inc_return_relaxed(&d->ref) <= 0);
+	page_ext_put(page_ext);
+}
+
+static void iommu_debug_dec_page(phys_addr_t phys)
+{
+	struct page_ext *page_ext = page_ext_from_phys(phys);
+	struct iommu_debug_metadata *d;
+
+	if (!page_ext)
+		return;
+
+	d = get_iommu_data(page_ext);
+	WARN_ON(atomic_dec_return_relaxed(&d->ref) < 0);
+	page_ext_put(page_ext);
+}
+
+/*
+ * IOMMU page size doesn't have to match the CPU page size. So, we use
+ * the smallest IOMMU page size to refcount the pages in the vmemmap.
+ * That is important as both map and unmap has to use the same page size
+ * to update the refcount to avoid double counting the same page.
+ * And as we can't know from iommu_unmap() what was the original page size
+ * used for map, we just use the minimum supported one for both.
+ */
+static size_t iommu_debug_page_size(struct iommu_domain *domain)
+{
+	return 1UL << __ffs(domain->pgsize_bitmap);
+}
+
+static bool iommu_debug_page_count(const struct page *page)
+{
+	unsigned int ref;
+	struct page_ext *page_ext = page_ext_get(page);
+	struct iommu_debug_metadata *d = get_iommu_data(page_ext);
+
+	ref = atomic_read(&d->ref);
+	page_ext_put(page_ext);
+	return ref != 0;
+}
+
+void __iommu_debug_check_unmapped(const struct page *page, int numpages)
+{
+	while (numpages--) {
+		if (WARN_ON(iommu_debug_page_count(page))) {
+			pr_warn("iommu: Detected page leak!\n");
+			dump_page_owner(page);
+		}
+		page++;
+	}
+}
+
+void __iommu_debug_map(struct iommu_domain *domain, phys_addr_t phys, size_t size)
+{
+	size_t off, end;
+	size_t page_size = iommu_debug_page_size(domain);
+
+	if (WARN_ON(!phys || check_add_overflow(phys, size, &end)))
+		return;
+
+	for (off = 0 ; off < size ; off += page_size)
+		iommu_debug_inc_page(phys + off);
+}
+
+static void __iommu_debug_update_iova(struct iommu_domain *domain,
+				      unsigned long iova, size_t size, bool inc)
+{
+	size_t off, end;
+	size_t page_size = iommu_debug_page_size(domain);
+
+	if (WARN_ON(check_add_overflow(iova, size, &end)))
+		return;
+
+	for (off = 0 ; off < size ; off += page_size) {
+		phys_addr_t phys = iommu_iova_to_phys(domain, iova + off);
+
+		if (!phys)
+			continue;
+
+		if (inc)
+			iommu_debug_inc_page(phys);
+		else
+			iommu_debug_dec_page(phys);
+	}
+}
+
+void __iommu_debug_unmap_begin(struct iommu_domain *domain,
+			       unsigned long iova, size_t size)
+{
+	__iommu_debug_update_iova(domain, iova, size, false);
+}
+
+void __iommu_debug_unmap_end(struct iommu_domain *domain,
+			     unsigned long iova, size_t size,
+			     size_t unmapped)
+{
+	if ((unmapped == size) || WARN_ON_ONCE(unmapped > size))
+		return;
+
+	/* If unmap failed, re-increment the refcount. */
+	__iommu_debug_update_iova(domain, iova + unmapped,
+				  size - unmapped, true);
+}
+
+void iommu_debug_init(void)
+{
+	if (!needed)
+		return;
+
+	pr_info("iommu: Debugging page allocations, expect overhead or disable iommu.debug_pagealloc");
+	static_branch_enable(&iommu_debug_initialized);
+}
+
+static int __init iommu_debug_pagealloc(char *str)
+{
+	return kstrtobool(str, &needed);
+}
+early_param("iommu.debug_pagealloc", iommu_debug_pagealloc);