Commit 7af08b57 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v6.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace 

Pull more tracing updates from Steven Rostedt:

 - Add trace flag for NEED_RESCHED_LAZY

   Now that NEED_RESCHED_LAZY is upstream, add it to the status bits of
   the common_flags. This will now show when the NEED_RESCHED_LAZY flag
   is set that is used for debugging latency issues in the kernel via a
   trace.

 - Remove leftover "__idx" variable when SRCU was removed from the
   tracepoint code

 - Add rcu_tasks_trace guard

   To add a guard() around the tracepoint code, a rcu_tasks_trace guard
   needs to be created first.

 - Remove __DO_TRACE() macro and just call __DO_TRACE_CALL() directly

   The DO_TRACE() macro has conditional locking depending on what was
   passed into the macro parameters. As the guts of the macro has been
   moved to __DO_TRACE_CALL() to handle static call logic, there's no
   reason to keep the __DO_TRACE() macro around.

   It is better to just do the locking in place without the conditionals
   and call __DO_TRACE_CALL() from those locations. The "cond" passed in
   can also be moved out of that macro. This simplifies the code.

 - Remove the "cond" from the system call tracepoint macros

   The "cond" variable was added to allow some tracepoints to check a
   condition within the static_branch (jump/nop) logic. The system calls
   do not need this. Removing it simplifies the code.

 - Replace scoped_guard() with just guard() in the tracepoint logic

   guard() works just as well as scoped_guard() in the tracepoint logic
   and the scoped_guard() causes some issues.

* tag 'trace-v6.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Use guard() rather than scoped_guard()
  tracing: Remove cond argument from __DECLARE_TRACE_SYSCALL
  tracing: Remove conditional locking from __DO_TRACE()
  rcupdate_trace: Define rcu_tasks_trace lock guard
  tracing: Remove __idx variable from __DO_TRACE
  tracing: Move it_func[0] comment to the relevant context
  tracing: Record task flag NEED_RESCHED_LAZY.
parents 65ae975e 2bd9b57d

Documentation/trace/ftrace.rst

+4 −0
Original line number Diff line number Diff line
@@ -1033,9 +1033,13 @@ explains which is which. 
  irqs-off: 'd' interrupts are disabled. '.' otherwise.



  need-resched:

	- 'B' all, TIF_NEED_RESCHED, PREEMPT_NEED_RESCHED and TIF_RESCHED_LAZY is set,

	- 'N' both TIF_NEED_RESCHED and PREEMPT_NEED_RESCHED is set,

	- 'n' only TIF_NEED_RESCHED is set,

	- 'p' only PREEMPT_NEED_RESCHED is set,

	- 'L' both PREEMPT_NEED_RESCHED and TIF_RESCHED_LAZY is set,

	- 'b' both TIF_NEED_RESCHED and TIF_RESCHED_LAZY is set,

	- 'l' only TIF_RESCHED_LAZY is set

	- '.' otherwise.



  hardirq/softirq:

include/linux/rcupdate_trace.h

+5 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 


#include <linux/sched.h>

#include <linux/rcupdate.h>

#include <linux/cleanup.h>



extern struct lockdep_map rcu_trace_lock_map;
@@ -98,4 +99,8 @@ static inline void rcu_read_lock_trace(void) { BUG(); } 
static inline void rcu_read_unlock_trace(void) { BUG(); }

#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */



DEFINE_LOCK_GUARD_0(rcu_tasks_trace,

	rcu_read_lock_trace(),

	rcu_read_unlock_trace())



#endif /* __LINUX_RCUPDATE_TRACE_H */

include/linux/trace_events.h

+1 −0
Original line number Diff line number Diff line
@@ -184,6 +184,7 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status); 


enum trace_flag_type {

	TRACE_FLAG_IRQS_OFF		= 0x01,

	TRACE_FLAG_NEED_RESCHED_LAZY	= 0x02,

	TRACE_FLAG_NEED_RESCHED		= 0x04,

	TRACE_FLAG_HARDIRQ		= 0x08,

	TRACE_FLAG_SOFTIRQ		= 0x10,

include/linux/tracepoint.h

+30 −52
Original line number Diff line number Diff line
@@ -209,36 +209,6 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 
#define __DO_TRACE_CALL(name, args)	__traceiter_##name(NULL, args)

#endif /* CONFIG_HAVE_STATIC_CALL */



/*

 * it_func[0] is never NULL because there is at least one element in the array

 * when the array itself is non NULL.

 *

 * With @syscall=0, the tracepoint callback array dereference is

 * protected by disabling preemption.

 * With @syscall=1, the tracepoint callback array dereference is

 * protected by Tasks Trace RCU, which allows probes to handle page

 * faults.

 */

#define __DO_TRACE(name, args, cond, syscall)				\

	do {								\

		int __maybe_unused __idx = 0;				\

									\

		if (!(cond))						\

			return;						\

									\

		if (syscall)						\

			rcu_read_lock_trace();				\

		else							\

			preempt_disable_notrace();			\

									\

		__DO_TRACE_CALL(name, TP_ARGS(args));			\

									\

		if (syscall)						\

			rcu_read_unlock_trace();			\

		else							\

			preempt_enable_notrace();			\

	} while (0)



/*

 * Declare an exported function that Rust code can call to trigger this

 * tracepoint. This function does not include the static branch; that is done
@@ -262,7 +232,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 
 * site if it is not watching, as it will need to be active when the

 * tracepoint is enabled.

 */

#define __DECLARE_TRACE_COMMON(name, proto, args, cond, data_proto)	\

#define __DECLARE_TRACE_COMMON(name, proto, args, data_proto)		\

	extern int __traceiter_##name(data_proto);			\

	DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name);	\

	extern struct tracepoint __tracepoint_##name;			\
@@ -297,41 +267,43 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 
	}



#define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\

	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), cond, PARAMS(data_proto)) \

	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \

	static inline void __rust_do_trace_##name(proto)		\

	{								\

		__DO_TRACE(name,					\

			TP_ARGS(args),					\

			TP_CONDITION(cond), 0);				\

		if (cond) {						\

			guard(preempt_notrace)();			\

			__DO_TRACE_CALL(name, TP_ARGS(args));		\

		}							\

	}								\

	static inline void trace_##name(proto)				\

	{								\

		if (static_branch_unlikely(&__tracepoint_##name.key))	\

			__DO_TRACE(name,				\

				TP_ARGS(args),				\

				TP_CONDITION(cond), 0);			\

		if (static_branch_unlikely(&__tracepoint_##name.key)) { \

			if (cond) {					\

				guard(preempt_notrace)();		\

				__DO_TRACE_CALL(name, TP_ARGS(args));	\

			}						\

		}							\

		if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {		\

			WARN_ONCE(!rcu_is_watching(),			\

				  "RCU not watching for tracepoint");	\

		}							\

	}



#define __DECLARE_TRACE_SYSCALL(name, proto, args, cond, data_proto)	\

	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), cond, PARAMS(data_proto)) \

#define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto)		\

	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \

	static inline void __rust_do_trace_##name(proto)		\

	{								\

		__DO_TRACE(name,					\

			TP_ARGS(args),					\

			TP_CONDITION(cond), 1);				\

		guard(rcu_tasks_trace)();				\

		__DO_TRACE_CALL(name, TP_ARGS(args));			\

	}								\

	static inline void trace_##name(proto)				\

	{								\

		might_fault();						\

		if (static_branch_unlikely(&__tracepoint_##name.key))	\

			__DO_TRACE(name,				\

				TP_ARGS(args),				\

				TP_CONDITION(cond), 1);			\

		if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {		\

		if (static_branch_unlikely(&__tracepoint_##name.key)) {	\

			guard(rcu_tasks_trace)();			\

			__DO_TRACE_CALL(name, TP_ARGS(args));		\

		}							\

		if (IS_ENABLED(CONFIG_LOCKDEP)) {			\

			WARN_ONCE(!rcu_is_watching(),			\

				  "RCU not watching for tracepoint");	\

		}							\
@@ -341,6 +313,9 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 
 * We have no guarantee that gcc and the linker won't up-align the tracepoint

 * structures, so we create an array of pointers that will be used for iteration

 * on the tracepoints.

 *

 * it_func[0] is never NULL because there is at least one element in the array

 * when the array itself is non NULL.

 */

#define __DEFINE_TRACE_EXT(_name, _ext, proto, args)			\

	static const char __tpstrtab_##_name[]				\
@@ -412,7 +387,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 




#else /* !TRACEPOINTS_ENABLED */

#define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\

#define __DECLARE_TRACE_COMMON(name, proto, args, data_proto)		\

	static inline void trace_##name(proto)				\

	{ }								\

	static inline int						\
@@ -436,7 +411,11 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 
		return false;						\

	}



#define __DECLARE_TRACE_SYSCALL	__DECLARE_TRACE

#define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\

	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))



#define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto)		\

	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))



#define DEFINE_TRACE_FN(name, reg, unreg, proto, args)

#define DEFINE_TRACE_SYSCALL(name, reg, unreg, proto, args)
@@ -502,7 +481,6 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 


#define DECLARE_TRACE_SYSCALL(name, proto, args)			\

	__DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args),	\

				cpu_online(raw_smp_processor_id()),	\

				PARAMS(void *__data, proto))



#define TRACE_EVENT_FLAGS(event, flag)

kernel/trace/trace.c

+2 −0
Original line number Diff line number Diff line
@@ -2552,6 +2552,8 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status) 
		trace_flags |= TRACE_FLAG_NEED_RESCHED;

	if (test_preempt_need_resched())

		trace_flags |= TRACE_FLAG_PREEMPT_RESCHED;

	if (IS_ENABLED(CONFIG_ARCH_HAS_PREEMPT_LAZY) && tif_test_bit(TIF_NEED_RESCHED_LAZY))

		trace_flags |= TRACE_FLAG_NEED_RESCHED_LAZY;

	return (trace_flags << 16) | (min_t(unsigned int, pc & 0xff, 0xf)) |

		(min_t(unsigned int, migration_disable_value(), 0xf)) << 4;

}