The following commit has been merged into the sched/core branch of tip:
Commit-ID: d099dbfd330686a8c09cd8944bcc77a56f9e7815
Gitweb: https://git.kernel.org/tip/d099dbfd330686a8c09cd8944bcc77a56f9e7815
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 26 Jan 2023 16:08:32 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 31 Jan 2023 15:01:46 +01:00
cpuidle: tracing: Warn about !rcu_is_watching()
When using noinstr, WARN when tracing hits when RCU is disabled.
Suggested-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230126151323.466670589@xxxxxxxxxxxxx
---
include/linux/trace_recursion.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index c303f7a..d48cd92 100644
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -135,6 +135,21 @@ extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip);
# define do_ftrace_record_recursion(ip, pip) do { } while (0)
#endif
+#ifdef CONFIG_ARCH_WANTS_NO_INSTR
+# define trace_warn_on_no_rcu(ip) \
+ ({ \
+ bool __ret = !rcu_is_watching(); \
+ if (__ret && !trace_recursion_test(TRACE_RECORD_RECURSION_BIT)) { \
+ trace_recursion_set(TRACE_RECORD_RECURSION_BIT); \
+ WARN_ONCE(true, "RCU not on for: %pS\n", (void *)ip); \
+ trace_recursion_clear(TRACE_RECORD_RECURSION_BIT); \
+ } \
+ __ret; \
+ })
+#else
+# define trace_warn_on_no_rcu(ip) false
+#endif
+
/*
* Preemption is promised to be disabled when return bit >= 0.
*/
@@ -144,6 +159,9 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign
unsigned int val = READ_ONCE(current->trace_recursion);
int bit;
+ if (trace_warn_on_no_rcu(ip))
+ return -1;
+
bit = trace_get_context_bit() + start;
if (unlikely(val & (1 << bit))) {
/*
|