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authorLinus Torvalds <torvalds@linux-foundation.org>2022-03-10 17:23:08 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-10 17:23:08 -0800
commitdda64ead7e82caa47fafe0edc36067ee64df2203 (patch)
treeb3640f49cd50e129228332f61d6cbcae883318d6 /kernel
parent186d32bbf034417b40e2b4e773eeb8ef106c16c1 (diff)
parent78cbc6513217b00be6a9904415ef7ff3619eb035 (diff)
downloadlinux-dda64ead7e82caa47fafe0edc36067ee64df2203.tar.bz2
Merge tag 'trace-v5.17-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt: "Minor tracing fixes: - Fix unregistering the same event twice. A user could disable the same event that osnoise will disable on unregistering. - Inform RCU of a quiescent state in the osnoise testing thread. - Fix some kerneldoc comments" * tag 'trace-v5.17-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace: Fix some W=1 warnings in kernel doc comments tracing/osnoise: Force quiescent states while tracing tracing/osnoise: Do not unregister events twice
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ftrace.c4
-rw-r--r--kernel/trace/trace_osnoise.c31
2 files changed, 33 insertions, 2 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a4b462b6f944..6105b7036482 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -7790,7 +7790,7 @@ int ftrace_is_dead(void)
/**
* register_ftrace_function - register a function for profiling
- * @ops - ops structure that holds the function for profiling.
+ * @ops: ops structure that holds the function for profiling.
*
* Register a function to be called by all functions in the
* kernel.
@@ -7817,7 +7817,7 @@ EXPORT_SYMBOL_GPL(register_ftrace_function);
/**
* unregister_ftrace_function - unregister a function for profiling.
- * @ops - ops structure that holds the function to unregister
+ * @ops: ops structure that holds the function to unregister
*
* Unregister a function that was added to be called by ftrace profiling.
*/
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index cfddb30e65ab..5e3c62a08fc0 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1387,6 +1387,26 @@ static int run_osnoise(void)
}
/*
+ * In some cases, notably when running on a nohz_full CPU with
+ * a stopped tick PREEMPT_RCU has no way to account for QSs.
+ * This will eventually cause unwarranted noise as PREEMPT_RCU
+ * will force preemption as the means of ending the current
+ * grace period. We avoid this problem by calling
+ * rcu_momentary_dyntick_idle(), which performs a zero duration
+ * EQS allowing PREEMPT_RCU to end the current grace period.
+ * This call shouldn't be wrapped inside an RCU critical
+ * section.
+ *
+ * Note that in non PREEMPT_RCU kernels QSs are handled through
+ * cond_resched()
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RCU)) {
+ local_irq_disable();
+ rcu_momentary_dyntick_idle();
+ local_irq_enable();
+ }
+
+ /*
* For the non-preemptive kernel config: let threads runs, if
* they so wish.
*/
@@ -2200,6 +2220,17 @@ static void osnoise_workload_stop(void)
if (osnoise_has_registered_instances())
return;
+ /*
+ * If callbacks were already disabled in a previous stop
+ * call, there is no need to disable then again.
+ *
+ * For instance, this happens when tracing is stopped via:
+ * echo 0 > tracing_on
+ * echo nop > current_tracer.
+ */
+ if (!trace_osnoise_callback_enabled)
+ return;
+
trace_osnoise_callback_enabled = false;
/*
* Make sure that ftrace_nmi_enter/exit() see