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, 155 insertions, 0 deletions

diff --git a/fs/fs_struct.c b/fs/fs_struct.c
new file mode 100644
index 000000000..394875d06
--- /dev/null
+++ b/fs/fs_struct.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/export.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/fs.h>
+#include <linux/path.h>
+#include <linux/slab.h>
+#include <linux/fs_struct.h>
+#include <linux/init_task.h>
+#include "internal.h"
+
+/*
+ * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
+ * It can block.
+ */
+void set_fs_root(struct fs_struct *fs, const struct path *path)
+{
+	struct path old_root;
+
+	path_get(path);
+	write_seqlock(&fs->seq);
+	old_root = fs->root;
+	fs->root = *path;
+	write_sequnlock(&fs->seq);
+	if (old_root.dentry)
+		path_put(&old_root);
+}
+
+/*
+ * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
+ * It can block.
+ */
+void set_fs_pwd(struct fs_struct *fs, const struct path *path)
+{
+	struct path old_pwd;
+
+	path_get(path);
+	write_seqlock(&fs->seq);
+	old_pwd = fs->pwd;
+	fs->pwd = *path;
+	write_sequnlock(&fs->seq);
+
+	if (old_pwd.dentry)
+		path_put(&old_pwd);
+}
+
+static inline int replace_path(struct path *p, const struct path *old, const struct path *new)
+{
+	if (likely(p->dentry != old->dentry || p->mnt != old->mnt))
+		return 0;
+	*p = *new;
+	return 1;
+}
+
+void chroot_fs_refs(const struct path *old_root, const struct path *new_root)
+{
+	struct task_struct *g, *p;
+	struct fs_struct *fs;
+	int count = 0;
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, p) {
+		task_lock(p);
+		fs = p->fs;
+		if (fs) {
+			int hits = 0;
+			write_seqlock(&fs->seq);
+			hits += replace_path(&fs->root, old_root, new_root);
+			hits += replace_path(&fs->pwd, old_root, new_root);
+			while (hits--) {
+				count++;
+				path_get(new_root);
+			}
+			write_sequnlock(&fs->seq);
+		}
+		task_unlock(p);
+	}
+	read_unlock(&tasklist_lock);
+	while (count--)
+		path_put(old_root);
+}
+
+void free_fs_struct(struct fs_struct *fs)
+{
+	path_put(&fs->root);
+	path_put(&fs->pwd);
+	kmem_cache_free(fs_cachep, fs);
+}
+
+void exit_fs(struct task_struct *tsk)
+{
+	struct fs_struct *fs = tsk->fs;
+
+	if (fs) {
+		int kill;
+		task_lock(tsk);
+		read_seqlock_excl(&fs->seq);
+		tsk->fs = NULL;
+		kill = !--fs->users;
+		read_sequnlock_excl(&fs->seq);
+		task_unlock(tsk);
+		if (kill)
+			free_fs_struct(fs);
+	}
+}
+
+struct fs_struct *copy_fs_struct(struct fs_struct *old)
+{
+	struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
+	/* We don't need to lock fs - think why ;-) */
+	if (fs) {
+		fs->users = 1;
+		fs->in_exec = 0;
+		seqlock_init(&fs->seq);
+		fs->umask = old->umask;
+
+		read_seqlock_excl(&old->seq);
+		fs->root = old->root;
+		path_get(&fs->root);
+		fs->pwd = old->pwd;
+		path_get(&fs->pwd);
+		read_sequnlock_excl(&old->seq);
+	}
+	return fs;
+}
+
+int unshare_fs_struct(void)
+{
+	struct fs_struct *fs = current->fs;
+	struct fs_struct *new_fs = copy_fs_struct(fs);
+	int kill;
+
+	if (!new_fs)
+		return -ENOMEM;
+
+	task_lock(current);
+	read_seqlock_excl(&fs->seq);
+	kill = !--fs->users;
+	current->fs = new_fs;
+	read_sequnlock_excl(&fs->seq);
+	task_unlock(current);
+
+	if (kill)
+		free_fs_struct(fs);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(unshare_fs_struct);
+
+/* to be mentioned only in INIT_TASK */
+struct fs_struct init_fs = {
+	.users		= 1,
+	.seq		= __SEQLOCK_UNLOCKED(init_fs.seq),
+	.umask		= 0022,
+};