Merge tag 'trace-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - Added new "bootconfig".

   This looks for a file appended to initrd to add boot config options,
   and has been discussed thoroughly at Linux Plumbers.

   Very useful for adding kprobes at bootup.

   Only enabled if "bootconfig" is on the real kernel command line.

 - Created dynamic event creation.

   Merges common code between creating synthetic events and kprobe
   events.

 - Rename perf "ring_buffer" structure to "perf_buffer"

 - Rename ftrace "ring_buffer" structure to "trace_buffer"

   Had to rename existing "trace_buffer" to "array_buffer"

 - Allow trace_printk() to work withing (some) tracing code.

 - Sort of tracing configs to be a little better organized

 - Fixed bug where ftrace_graph hash was not being protected properly

 - Various other small fixes and clean ups

* tag 'trace-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (88 commits)
  bootconfig: Show the number of nodes on boot message
  tools/bootconfig: Show the number of bootconfig nodes
  bootconfig: Add more parse error messages
  bootconfig: Use bootconfig instead of boot config
  ftrace: Protect ftrace_graph_hash with ftrace_sync
  ftrace: Add comment to why rcu_dereference_sched() is open coded
  tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu
  tracing: Annotate ftrace_graph_hash pointer with __rcu
  bootconfig: Only load bootconfig if "bootconfig" is on the kernel cmdline
  tracing: Use seq_buf for building dynevent_cmd string
  tracing: Remove useless code in dynevent_arg_pair_add()
  tracing: Remove check_arg() callbacks from dynevent args
  tracing: Consolidate some synth_event_trace code
  tracing: Fix now invalid var_ref_vals assumption in trace action
  tracing: Change trace_boot to use synth_event interface
  tracing: Move tracing selftests to bottom of menu
  tracing: Move mmio tracer config up with the other tracers
  tracing: Move tracing test module configs together
  tracing: Move all function tracing configs together
  tracing: Documentation for in-kernel synthetic event API
  ...

33 files changed, 3277 insertions, 682 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 25a0fcfa7a5d..91e885194dbc 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -141,6 +141,15 @@ menuconfig FTRACE
 
 if FTRACE
 
+config BOOTTIME_TRACING
+	bool "Boot-time Tracing support"
+	depends on BOOT_CONFIG && TRACING
+	default y
+	help
+	  Enable developer to setup ftrace subsystem via supplemental
+	  kernel cmdline at boot time for debugging (tracing) driver
+	  initialization and boot process.
+
 config FUNCTION_TRACER
 	bool "Kernel Function Tracer"
 	depends on HAVE_FUNCTION_TRACER
@@ -172,6 +181,77 @@ config FUNCTION_GRAPH_TRACER
 	  the return value. This is done by setting the current return
 	  address on the current task structure into a stack of calls.
 
+config DYNAMIC_FTRACE
+	bool "enable/disable function tracing dynamically"
+	depends on FUNCTION_TRACER
+	depends on HAVE_DYNAMIC_FTRACE
+	default y
+	help
+	  This option will modify all the calls to function tracing
+	  dynamically (will patch them out of the binary image and
+	  replace them with a No-Op instruction) on boot up. During
+	  compile time, a table is made of all the locations that ftrace
+	  can function trace, and this table is linked into the kernel
+	  image. When this is enabled, functions can be individually
+	  enabled, and the functions not enabled will not affect
+	  performance of the system.
+
+	  See the files in /sys/kernel/debug/tracing:
+	    available_filter_functions
+	    set_ftrace_filter
+	    set_ftrace_notrace
+
+	  This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
+	  otherwise has native performance as long as no tracing is active.
+
+config DYNAMIC_FTRACE_WITH_REGS
+	def_bool y
+	depends on DYNAMIC_FTRACE
+	depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
+
+config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
+	def_bool y
+	depends on DYNAMIC_FTRACE
+	depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
+
+config FUNCTION_PROFILER
+	bool "Kernel function profiler"
+	depends on FUNCTION_TRACER
+	default n
+	help
+	  This option enables the kernel function profiler. A file is created
+	  in debugfs called function_profile_enabled which defaults to zero.
+	  When a 1 is echoed into this file profiling begins, and when a
+	  zero is entered, profiling stops. A "functions" file is created in
+	  the trace_stat directory; this file shows the list of functions that
+	  have been hit and their counters.
+
+	  If in doubt, say N.
+
+config STACK_TRACER
+	bool "Trace max stack"
+	depends on HAVE_FUNCTION_TRACER
+	select FUNCTION_TRACER
+	select STACKTRACE
+	select KALLSYMS
+	help
+	  This special tracer records the maximum stack footprint of the
+	  kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
+
+	  This tracer works by hooking into every function call that the
+	  kernel executes, and keeping a maximum stack depth value and
+	  stack-trace saved.  If this is configured with DYNAMIC_FTRACE
+	  then it will not have any overhead while the stack tracer
+	  is disabled.
+
+	  To enable the stack tracer on bootup, pass in 'stacktrace'
+	  on the kernel command line.
+
+	  The stack tracer can also be enabled or disabled via the
+	  sysctl kernel.stack_tracer_enabled
+
+	  Say N if unsure.
+
 config TRACE_PREEMPT_TOGGLE
 	bool
 	help
@@ -282,6 +362,19 @@ config HWLAT_TRACER
 	 file. Every time a latency is greater than tracing_thresh, it will
 	 be recorded into the ring buffer.
 
+config MMIOTRACE
+	bool "Memory mapped IO tracing"
+	depends on HAVE_MMIOTRACE_SUPPORT && PCI
+	select GENERIC_TRACER
+	help
+	  Mmiotrace traces Memory Mapped I/O access and is meant for
+	  debugging and reverse engineering. It is called from the ioremap
+	  implementation and works via page faults. Tracing is disabled by
+	  default and can be enabled at run-time.
+
+	  See Documentation/trace/mmiotrace.rst.
+	  If you are not helping to develop drivers, say N.
+
 config ENABLE_DEFAULT_TRACERS
 	bool "Trace process context switches and events"
 	depends on !GENERIC_TRACER
@@ -410,30 +503,6 @@ config BRANCH_TRACER
 
 	  Say N if unsure.
 
-config STACK_TRACER
-	bool "Trace max stack"
-	depends on HAVE_FUNCTION_TRACER
-	select FUNCTION_TRACER
-	select STACKTRACE
-	select KALLSYMS
-	help
-	  This special tracer records the maximum stack footprint of the
-	  kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
-
-	  This tracer works by hooking into every function call that the
-	  kernel executes, and keeping a maximum stack depth value and
-	  stack-trace saved.  If this is configured with DYNAMIC_FTRACE
-	  then it will not have any overhead while the stack tracer
-	  is disabled.
-
-	  To enable the stack tracer on bootup, pass in 'stacktrace'
-	  on the kernel command line.
-
-	  The stack tracer can also be enabled or disabled via the
-	  sysctl kernel.stack_tracer_enabled
-
-	  Say N if unsure.
-
 config BLK_DEV_IO_TRACE
 	bool "Support for tracing block IO actions"
 	depends on SYSFS
@@ -531,53 +600,6 @@ config DYNAMIC_EVENTS
 config PROBE_EVENTS
 	def_bool n
 
-config DYNAMIC_FTRACE
-	bool "enable/disable function tracing dynamically"
-	depends on FUNCTION_TRACER
-	depends on HAVE_DYNAMIC_FTRACE
-	default y
-	help
-	  This option will modify all the calls to function tracing
-	  dynamically (will patch them out of the binary image and
-	  replace them with a No-Op instruction) on boot up. During
-	  compile time, a table is made of all the locations that ftrace
-	  can function trace, and this table is linked into the kernel
-	  image. When this is enabled, functions can be individually
-	  enabled, and the functions not enabled will not affect
-	  performance of the system.
-
-	  See the files in /sys/kernel/debug/tracing:
-	    available_filter_functions
-	    set_ftrace_filter
-	    set_ftrace_notrace
-
-	  This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
-	  otherwise has native performance as long as no tracing is active.
-
-config DYNAMIC_FTRACE_WITH_REGS
-	def_bool y
-	depends on DYNAMIC_FTRACE
-	depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
-
-config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
-	def_bool y
-	depends on DYNAMIC_FTRACE
-	depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
-
-config FUNCTION_PROFILER
-	bool "Kernel function profiler"
-	depends on FUNCTION_TRACER
-	default n
-	help
-	  This option enables the kernel function profiler. A file is created
-	  in debugfs called function_profile_enabled which defaults to zero.
-	  When a 1 is echoed into this file profiling begins, and when a
-	  zero is entered, profiling stops. A "functions" file is created in
-	  the trace_stat directory; this file shows the list of functions that
-	  have been hit and their counters.
-
-	  If in doubt, say N.
-
 config BPF_KPROBE_OVERRIDE
 	bool "Enable BPF programs to override a kprobed function"
 	depends on BPF_EVENTS
@@ -592,54 +614,6 @@ config FTRACE_MCOUNT_RECORD
 	depends on DYNAMIC_FTRACE
 	depends on HAVE_FTRACE_MCOUNT_RECORD
 
-config FTRACE_SELFTEST
-	bool
-
-config FTRACE_STARTUP_TEST
-	bool "Perform a startup test on ftrace"
-	depends on GENERIC_TRACER
-	select FTRACE_SELFTEST
-	help
-	  This option performs a series of startup tests on ftrace. On bootup
-	  a series of tests are made to verify that the tracer is
-	  functioning properly. It will do tests on all the configured
-	  tracers of ftrace.
-
-config EVENT_TRACE_STARTUP_TEST
-	bool "Run selftest on trace events"
-	depends on FTRACE_STARTUP_TEST
-	default y
-	help
-	  This option performs a test on all trace events in the system.
-	  It basically just enables each event and runs some code that
-	  will trigger events (not necessarily the event it enables)
-	  This may take some time run as there are a lot of events.
-
-config EVENT_TRACE_TEST_SYSCALLS
-	bool "Run selftest on syscall events"
-	depends on EVENT_TRACE_STARTUP_TEST
-	help
-	 This option will also enable testing every syscall event.
-	 It only enables the event and disables it and runs various loads
-	 with the event enabled. This adds a bit more time for kernel boot
-	 up since it runs this on every system call defined.
-
-	 TBD - enable a way to actually call the syscalls as we test their
-	       events
-
-config MMIOTRACE
-	bool "Memory mapped IO tracing"
-	depends on HAVE_MMIOTRACE_SUPPORT && PCI
-	select GENERIC_TRACER
-	help
-	  Mmiotrace traces Memory Mapped I/O access and is meant for
-	  debugging and reverse engineering. It is called from the ioremap
-	  implementation and works via page faults. Tracing is disabled by
-	  default and can be enabled at run-time.
-
-	  See Documentation/trace/mmiotrace.rst.
-	  If you are not helping to develop drivers, say N.
-
 config TRACING_MAP
 	bool
 	depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
@@ -680,16 +654,6 @@ config TRACE_EVENT_INJECT
 
 	  If unsure, say N.
 
-config MMIOTRACE_TEST
-	tristate "Test module for mmiotrace"
-	depends on MMIOTRACE && m
-	help
-	  This is a dumb module for testing mmiotrace. It is very dangerous
-	  as it will write garbage to IO memory starting at a given address.
-	  However, it should be safe to use on e.g. unused portion of VRAM.
-
-	  Say N, unless you absolutely know what you are doing.
-
 config TRACEPOINT_BENCHMARK
 	bool "Add tracepoint that benchmarks tracepoints"
 	help
@@ -736,6 +700,81 @@ config RING_BUFFER_BENCHMARK
 
 	  If unsure, say N.
 
+config TRACE_EVAL_MAP_FILE
+       bool "Show eval mappings for trace events"
+       depends on TRACING
+       help
+	The "print fmt" of the trace events will show the enum/sizeof names
+	instead of their values. This can cause problems for user space tools
+	that use this string to parse the raw data as user space does not know
+	how to convert the string to its value.
+
+	To fix this, there's a special macro in the kernel that can be used
+	to convert an enum/sizeof into its value. If this macro is used, then
+	the print fmt strings will be converted to their values.
+
+	If something does not get converted properly, this option can be
+	used to show what enums/sizeof the kernel tried to convert.
+
+	This option is for debugging the conversions. A file is created
+	in the tracing directory called "eval_map" that will show the
+	names matched with their values and what trace event system they
+	belong too.
+
+	Normally, the mapping of the strings to values will be freed after
+	boot up or module load. With this option, they will not be freed, as
+	they are needed for the "eval_map" file. Enabling this option will
+	increase the memory footprint of the running kernel.
+
+	If unsure, say N.
+
+config GCOV_PROFILE_FTRACE
+	bool "Enable GCOV profiling on ftrace subsystem"
+	depends on GCOV_KERNEL
+	help
+	  Enable GCOV profiling on ftrace subsystem for checking
+	  which functions/lines are tested.
+
+	  If unsure, say N.
+
+	  Note that on a kernel compiled with this config, ftrace will
+	  run significantly slower.
+
+config FTRACE_SELFTEST
+	bool
+
+config FTRACE_STARTUP_TEST
+	bool "Perform a startup test on ftrace"
+	depends on GENERIC_TRACER
+	select FTRACE_SELFTEST
+	help
+	  This option performs a series of startup tests on ftrace. On bootup
+	  a series of tests are made to verify that the tracer is
+	  functioning properly. It will do tests on all the configured
+	  tracers of ftrace.
+
+config EVENT_TRACE_STARTUP_TEST
+	bool "Run selftest on trace events"
+	depends on FTRACE_STARTUP_TEST
+	default y
+	help
+	  This option performs a test on all trace events in the system.
+	  It basically just enables each event and runs some code that
+	  will trigger events (not necessarily the event it enables)
+	  This may take some time run as there are a lot of events.
+
+config EVENT_TRACE_TEST_SYSCALLS
+	bool "Run selftest on syscall events"
+	depends on EVENT_TRACE_STARTUP_TEST
+	help
+	 This option will also enable testing every syscall event.
+	 It only enables the event and disables it and runs various loads
+	 with the event enabled. This adds a bit more time for kernel boot
+	 up since it runs this on every system call defined.
+
+	 TBD - enable a way to actually call the syscalls as we test their
+	       events
+
 config RING_BUFFER_STARTUP_TEST
        bool "Ring buffer startup self test"
        depends on RING_BUFFER
@@ -759,8 +798,18 @@ config RING_BUFFER_STARTUP_TEST
 
 	 If unsure, say N
 
+config MMIOTRACE_TEST
+	tristate "Test module for mmiotrace"
+	depends on MMIOTRACE && m
+	help
+	  This is a dumb module for testing mmiotrace. It is very dangerous
+	  as it will write garbage to IO memory starting at a given address.
+	  However, it should be safe to use on e.g. unused portion of VRAM.
+
+	  Say N, unless you absolutely know what you are doing.
+
 config PREEMPTIRQ_DELAY_TEST
-	tristate "Preempt / IRQ disable delay thread to test latency tracers"
+	tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
 	depends on m
 	help
 	  Select this option to build a test module that can help test latency
@@ -774,45 +823,30 @@ config PREEMPTIRQ_DELAY_TEST
 
 	  If unsure, say N
 
-config TRACE_EVAL_MAP_FILE
-       bool "Show eval mappings for trace events"
-       depends on TRACING
-       help
-	The "print fmt" of the trace events will show the enum/sizeof names
-	instead of their values. This can cause problems for user space tools
-	that use this string to parse the raw data as user space does not know
-	how to convert the string to its value.
-
-	To fix this, there's a special macro in the kernel that can be used
-	to convert an enum/sizeof into its value. If this macro is used, then
-	the print fmt strings will be converted to their values.
-
-	If something does not get converted properly, this option can be
-	used to show what enums/sizeof the kernel tried to convert.
-
-	This option is for debugging the conversions. A file is created
-	in the tracing directory called "eval_map" that will show the
-	names matched with their values and what trace event system they
-	belong too.
+config SYNTH_EVENT_GEN_TEST
+	tristate "Test module for in-kernel synthetic event generation"
+	depends on HIST_TRIGGERS
+	help
+          This option creates a test module to check the base
+          functionality of in-kernel synthetic event definition and
+          generation.
 
-	Normally, the mapping of the strings to values will be freed after
-	boot up or module load. With this option, they will not be freed, as
-	they are needed for the "eval_map" file. Enabling this option will
-	increase the memory footprint of the running kernel.
+          To test, insert the module, and then check the trace buffer
+	  for the generated sample events.
 
-	If unsure, say N.
+	  If unsure, say N.
 
-config GCOV_PROFILE_FTRACE
-	bool "Enable GCOV profiling on ftrace subsystem"
-	depends on GCOV_KERNEL
+config KPROBE_EVENT_GEN_TEST
+	tristate "Test module for in-kernel kprobe event generation"
+	depends on KPROBE_EVENTS
 	help
-	  Enable GCOV profiling on ftrace subsystem for checking
-	  which functions/lines are tested.
+          This option creates a test module to check the base
+          functionality of in-kernel kprobe event definition.
 
-	  If unsure, say N.
+          To test, insert the module, and then check the trace buffer
+	  for the generated kprobe events.
 
-	  Note that on a kernel compiled with this config, ftrace will
-	  run significantly slower.
+	  If unsure, say N.
 
 endif # FTRACE
 
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 0e63db62225f..f9dcd19165fa 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -44,6 +44,8 @@ obj-$(CONFIG_TRACING) += trace_stat.o
 obj-$(CONFIG_TRACING) += trace_printk.o
 obj-$(CONFIG_TRACING_MAP) += tracing_map.o
 obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o
+obj-$(CONFIG_SYNTH_EVENT_GEN_TEST) += synth_event_gen_test.o
+obj-$(CONFIG_KPROBE_EVENT_GEN_TEST) += kprobe_event_gen_test.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
 obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
 obj-$(CONFIG_PREEMPTIRQ_TRACEPOINTS) += trace_preemptirq.o
@@ -83,6 +85,7 @@ endif
 obj-$(CONFIG_DYNAMIC_EVENTS) += trace_dynevent.o
 obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
 obj-$(CONFIG_UPROBE_EVENTS) += trace_uprobe.o
+obj-$(CONFIG_BOOTTIME_TRACING) += trace_boot.o
 
 obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
 
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 475e29498bca..0735ae8545d8 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -68,14 +68,14 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 {
 	struct blk_io_trace *t;
 	struct ring_buffer_event *event = NULL;
-	struct ring_buffer *buffer = NULL;
+	struct trace_buffer *buffer = NULL;
 	int pc = 0;
 	int cpu = smp_processor_id();
 	bool blk_tracer = blk_tracer_enabled;
 	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
 
 	if (blk_tracer) {
-		buffer = blk_tr->trace_buffer.buffer;
+		buffer = blk_tr->array_buffer.buffer;
 		pc = preempt_count();
 		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 						  sizeof(*t) + len + cgid_len,
@@ -215,7 +215,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 {
 	struct task_struct *tsk = current;
 	struct ring_buffer_event *event = NULL;
-	struct ring_buffer *buffer = NULL;
+	struct trace_buffer *buffer = NULL;
 	struct blk_io_trace *t;
 	unsigned long flags = 0;
 	unsigned long *sequence;
@@ -248,7 +248,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	if (blk_tracer) {
 		tracing_record_cmdline(current);
 
-		buffer = blk_tr->trace_buffer.buffer;
+		buffer = blk_tr->array_buffer.buffer;
 		pc = preempt_count();
 		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 						  sizeof(*t) + pdu_len + cgid_len,
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9bf1f2cd515e..3f7ee102868a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -62,8 +62,6 @@
 	})
 
 /* hash bits for specific function selection */
-#define FTRACE_HASH_BITS 7
-#define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)
 #define FTRACE_HASH_DEFAULT_BITS 10
 #define FTRACE_HASH_MAX_BITS 12
 
@@ -146,7 +144,7 @@ static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
 {
 	struct trace_array *tr = op->private;
 
-	if (tr && this_cpu_read(tr->trace_buffer.data->ftrace_ignore_pid))
+	if (tr && this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid))
 		return;
 
 	op->saved_func(ip, parent_ip, op, regs);
@@ -1103,9 +1101,6 @@ struct ftrace_page {
 #define ENTRY_SIZE sizeof(struct dyn_ftrace)
 #define ENTRIES_PER_PAGE (PAGE_SIZE / ENTRY_SIZE)
 
-/* estimate from running different kernels */
-#define NR_TO_INIT		10000
-
 static struct ftrace_page	*ftrace_pages_start;
 static struct ftrace_page	*ftrace_pages;
 
@@ -5464,7 +5459,7 @@ static void __init set_ftrace_early_graph(char *buf, int enable)
 	struct ftrace_hash *hash;
 
 	hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
-	if (WARN_ON(!hash))
+	if (MEM_FAIL(!hash, "Failed to allocate hash\n"))
 		return;
 
 	while (buf) {
@@ -5596,8 +5591,8 @@ static const struct file_operations ftrace_notrace_fops = {
 
 static DEFINE_MUTEX(graph_lock);
 
-struct ftrace_hash *ftrace_graph_hash = EMPTY_HASH;
-struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
+struct ftrace_hash __rcu *ftrace_graph_hash = EMPTY_HASH;
+struct ftrace_hash __rcu *ftrace_graph_notrace_hash = EMPTY_HASH;
 
 enum graph_filter_type {
 	GRAPH_FILTER_NOTRACE	= 0,
@@ -5872,8 +5867,15 @@ ftrace_graph_release(struct inode *inode, struct file *file)
 
 		mutex_unlock(&graph_lock);
 
-		/* Wait till all users are no longer using the old hash */
-		synchronize_rcu();
+		/*
+		 * We need to do a hard force of sched synchronization.
+		 * This is because we use preempt_disable() to do RCU, but
+		 * the function tracers can be called where RCU is not watching
+		 * (like before user_exit()). We can not rely on the RCU
+		 * infrastructure to do the synchronization, thus we must do it
+		 * ourselves.
+		 */
+		schedule_on_each_cpu(ftrace_sync);
 
 		free_ftrace_hash(old_hash);
 	}
@@ -6596,7 +6598,7 @@ static void add_to_clear_hash_list(struct list_head *clear_list,
 
 	func = kmalloc(sizeof(*func), GFP_KERNEL);
 	if (!func) {
-		WARN_ONCE(1, "alloc failure, ftrace filter could be stale\n");
+		MEM_FAIL(1, "alloc failure, ftrace filter could be stale\n");
 		return;
 	}
 
@@ -6922,7 +6924,7 @@ ftrace_filter_pid_sched_switch_probe(void *data, bool preempt,
 
 	pid_list = rcu_dereference_sched(tr->function_pids);
 
-	this_cpu_write(tr->trace_buffer.data->ftrace_ignore_pid,
+	this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid,
 		       trace_ignore_this_task(pid_list, next));
 }
 
@@ -6976,7 +6978,7 @@ static void clear_ftrace_pids(struct trace_array *tr)
 	unregister_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr);
 
 	for_each_possible_cpu(cpu)
-		per_cpu_ptr(tr->trace_buffer.data, cpu)->ftrace_ignore_pid = false;
+		per_cpu_ptr(tr->array_buffer.data, cpu)->ftrace_ignore_pid = false;
 
 	rcu_assign_pointer(tr->function_pids, NULL);
 
@@ -7031,9 +7033,10 @@ static void *fpid_next(struct seq_file *m, void *v, loff_t *pos)
 	struct trace_array *tr = m->private;
 	struct trace_pid_list *pid_list = rcu_dereference_sched(tr->function_pids);
 
-	if (v == FTRACE_NO_PIDS)
+	if (v == FTRACE_NO_PIDS) {
+		(*pos)++;
 		return NULL;
-
+	}
 	return trace_pid_next(pid_list, v, pos);
 }
 
@@ -7100,7 +7103,7 @@ static void ignore_task_cpu(void *data)
 	pid_list = rcu_dereference_protected(tr->function_pids,
 					     mutex_is_locked(&ftrace_lock));
 
-	this_cpu_write(tr->trace_buffer.data->ftrace_ignore_pid,
+	this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid,
 		       trace_ignore_this_task(pid_list, current));
 }
 
diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
new file mode 100644
index 000000000000..18b0f1cbb947
--- /dev/null
+++ b/kernel/trace/kprobe_event_gen_test.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test module for in-kernel kprobe event creation and generation.
+ *
+ * Copyright (C) 2019 Tom Zanussi <zanussi@kernel.org>
+ */
+
+#include <linux/module.h>
+#include <linux/trace_events.h>
+
+/*
+ * This module is a simple test of basic functionality for in-kernel
+ * kprobe/kretprobe event creation.  The first test uses
+ * kprobe_event_gen_cmd_start(), kprobe_event_add_fields() and
+ * kprobe_event_gen_cmd_end() to create a kprobe event, which is then
+ * enabled in order to generate trace output.  The second creates a
+ * kretprobe event using kretprobe_event_gen_cmd_start() and
+ * kretprobe_event_gen_cmd_end(), and is also then enabled.
+ *
+ * To test, select CONFIG_KPROBE_EVENT_GEN_TEST and build the module.
+ * Then:
+ *
+ * # insmod kernel/trace/kprobe_event_gen_test.ko
+ * # cat /sys/kernel/debug/tracing/trace
+ *
+ * You should see many instances of the "gen_kprobe_test" and
+ * "gen_kretprobe_test" events in the trace buffer.
+ *
+ * To remove the events, remove the module:
+ *
+ * # rmmod kprobe_event_gen_test
+ *
+ */
+
+static struct trace_event_file *gen_kprobe_test;
+static struct trace_event_file *gen_kretprobe_test;
+
+/*
+ * Test to make sure we can create a kprobe event, then add more
+ * fields.
+ */
+static int __init test_gen_kprobe_cmd(void)
+{
+	struct dynevent_cmd cmd;
+	char *buf;
+	int ret;
+
+	/* Create a buffer to hold the generated command */
+	buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* Before generating the command, initialize the cmd object */
+	kprobe_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);
+
+	/*
+	 * Define the gen_kprobe_test event with the first 2 kprobe
+	 * fields.
+	 */
+	ret = kprobe_event_gen_cmd_start(&cmd, "gen_kprobe_test",
+					 "do_sys_open",
+					 "dfd=%ax", "filename=%dx");
+	if (ret)
+		goto free;
+
+	/* Use kprobe_event_add_fields to add the rest of the fields */
+
+	ret = kprobe_event_add_fields(&cmd, "flags=%cx", "mode=+4($stack)");
+	if (ret)
+		goto free;
+
+	/*
+	 * This actually creates the event.
+	 */
+	ret = kprobe_event_gen_cmd_end(&cmd);
+	if (ret)
+		goto free;
+
+	/*
+	 * Now get the gen_kprobe_test event file.  We need to prevent
+	 * the instance and event from disappearing from underneath
+	 * us, which trace_get_event_file() does (though in this case
+	 * we're using the top-level instance which never goes away).
+	 */
+	gen_kprobe_test = trace_get_event_file(NULL, "kprobes",
+					       "gen_kprobe_test");
+	if (IS_ERR(gen_kprobe_test)) {
+		ret = PTR_ERR(gen_kprobe_test);
+		goto delete;
+	}
+
+	/* Enable the event or you won't see anything */
+	ret = trace_array_set_clr_event(gen_kprobe_test->tr,
+					"kprobes", "gen_kprobe_test", true);
+	if (ret) {
+		trace_put_event_file(gen_kprobe_test);
+		goto delete;
+	}
+ out:
+	return ret;
+ delete:
+	/* We got an error after creating the event, delete it */
+	ret = kprobe_event_delete("gen_kprobe