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-rw-r--r--include/linux/tracepoint.h40
-rw-r--r--kernel/tracepoint.c16
2 files changed, 47 insertions, 9 deletions
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 19a690b559ca..d9a084c72541 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -15,6 +15,7 @@
*/
#include <linux/smp.h>
+#include <linux/srcu.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/cpumask.h>
@@ -33,6 +34,8 @@ struct trace_eval_map {
#define TRACEPOINT_DEFAULT_PRIO 10
+extern struct srcu_struct tracepoint_srcu;
+
extern int
tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
extern int
@@ -75,10 +78,16 @@ int unregister_tracepoint_module_notifier(struct notifier_block *nb)
* probe unregistration and the end of module exit to make sure there is no
* caller executing a probe when it is freed.
*/
+#ifdef CONFIG_TRACEPOINTS
static inline void tracepoint_synchronize_unregister(void)
{
+ synchronize_srcu(&tracepoint_srcu);
synchronize_sched();
}
+#else
+static inline void tracepoint_synchronize_unregister(void)
+{ }
+#endif
#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
extern int syscall_regfunc(void);
@@ -129,18 +138,31 @@ extern void syscall_unregfunc(void);
* as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
* "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
*/
-#define __DO_TRACE(tp, proto, args, cond, rcucheck) \
+#define __DO_TRACE(tp, proto, args, cond, rcuidle) \
do { \
struct tracepoint_func *it_func_ptr; \
void *it_func; \
void *__data; \
+ int __maybe_unused idx = 0; \
\
if (!(cond)) \
return; \
- if (rcucheck) \
- rcu_irq_enter_irqson(); \
- rcu_read_lock_sched_notrace(); \
- it_func_ptr = rcu_dereference_sched((tp)->funcs); \
+ \
+ /* srcu can't be used from NMI */ \
+ WARN_ON_ONCE(rcuidle && in_nmi()); \
+ \
+ /* keep srcu and sched-rcu usage consistent */ \
+ preempt_disable_notrace(); \
+ \
+ /* \
+ * For rcuidle callers, use srcu since sched-rcu \
+ * doesn't work from the idle path. \
+ */ \
+ if (rcuidle) \
+ idx = srcu_read_lock_notrace(&tracepoint_srcu); \
+ \
+ it_func_ptr = rcu_dereference_raw((tp)->funcs); \
+ \
if (it_func_ptr) { \
do { \
it_func = (it_func_ptr)->func; \
@@ -148,9 +170,11 @@ extern void syscall_unregfunc(void);
((void(*)(proto))(it_func))(args); \
} while ((++it_func_ptr)->func); \
} \
- rcu_read_unlock_sched_notrace(); \
- if (rcucheck) \
- rcu_irq_exit_irqson(); \
+ \
+ if (rcuidle) \
+ srcu_read_unlock_notrace(&tracepoint_srcu, idx);\
+ \
+ preempt_enable_notrace(); \
} while (0)
#ifndef MODULE
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 6dc6356c3327..955148d91b74 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -31,6 +31,9 @@
extern struct tracepoint * const __start___tracepoints_ptrs[];
extern struct tracepoint * const __stop___tracepoints_ptrs[];
+DEFINE_SRCU(tracepoint_srcu);
+EXPORT_SYMBOL_GPL(tracepoint_srcu);
+
/* Set to 1 to enable tracepoint debug output */
static const int tracepoint_debug;
@@ -67,16 +70,27 @@ static inline void *allocate_probes(int count)
return p == NULL ? NULL : p->probes;
}
-static void rcu_free_old_probes(struct rcu_head *head)
+static void srcu_free_old_probes(struct rcu_head *head)
{
kfree(container_of(head, struct tp_probes, rcu));
}
+static void rcu_free_old_probes(struct rcu_head *head)
+{
+ call_srcu(&tracepoint_srcu, head, srcu_free_old_probes);
+}
+
static inline void release_probes(struct tracepoint_func *old)
{
if (old) {
struct tp_probes *tp_probes = container_of(old,
struct tp_probes, probes[0]);
+ /*
+ * Tracepoint probes are protected by both sched RCU and SRCU,
+ * by calling the SRCU callback in the sched RCU callback we
+ * cover both cases. So let us chain the SRCU and sched RCU
+ * callbacks to wait for both grace periods.
+ */
call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes);
}
}