ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/rust/helpers/cpumask.c b/rust/helpers/cpumask.c
new file mode 100644
index 000000000..5deced5b9
--- /dev/null
+++ b/rust/helpers/cpumask.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/cpumask.h>
+
+__rust_helper
+void rust_helper_cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
+{
+	cpumask_set_cpu(cpu, dstp);
+}
+
+__rust_helper
+void rust_helper___cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
+{
+	__cpumask_set_cpu(cpu, dstp);
+}
+
+__rust_helper
+void rust_helper_cpumask_clear_cpu(int cpu, struct cpumask *dstp)
+{
+	cpumask_clear_cpu(cpu, dstp);
+}
+
+__rust_helper
+void rust_helper___cpumask_clear_cpu(int cpu, struct cpumask *dstp)
+{
+	__cpumask_clear_cpu(cpu, dstp);
+}
+
+__rust_helper
+bool rust_helper_cpumask_test_cpu(int cpu, struct cpumask *srcp)
+{
+	return cpumask_test_cpu(cpu, srcp);
+}
+
+__rust_helper
+void rust_helper_cpumask_setall(struct cpumask *dstp)
+{
+	cpumask_setall(dstp);
+}
+
+__rust_helper
+bool rust_helper_cpumask_empty(struct cpumask *srcp)
+{
+	return cpumask_empty(srcp);
+}
+
+__rust_helper
+bool rust_helper_cpumask_full(struct cpumask *srcp)
+{
+	return cpumask_full(srcp);
+}
+
+__rust_helper
+unsigned int rust_helper_cpumask_weight(struct cpumask *srcp)
+{
+	return cpumask_weight(srcp);
+}
+
+__rust_helper
+void rust_helper_cpumask_copy(struct cpumask *dstp, const struct cpumask *srcp)
+{
+	cpumask_copy(dstp, srcp);
+}
+
+__rust_helper
+bool rust_helper_alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
+{
+	return alloc_cpumask_var(mask, flags);
+}
+
+__rust_helper
+bool rust_helper_zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
+{
+	return zalloc_cpumask_var(mask, flags);
+}
+
+#ifndef CONFIG_CPUMASK_OFFSTACK
+__rust_helper
+void rust_helper_free_cpumask_var(cpumask_var_t mask)
+{
+	free_cpumask_var(mask);
+}
+#endif