[for-linus][PATCH 0/7] tracing: A few more fixes for 6.5

[for-linus][PATCH 0/7] tracing: A few more fixes for 6.5

[Steven Rostedt]

Tracing fixes for 6.5:

- Fix to /sys/kernel/tracing/per_cpu/cpu*/stats read and entries.
  If a resize shrinks the buffer it clears the read count to notify
  readers that they need to reset. But the read count is also used for
  accounting and this causes the numbers to be off. Instead, create a
  separate variable to use to notify readers to reset.

- Fix the ref counts of the "soft disable" mode. The wrong value was
  used for testing if soft disable mode should be enabled or disable,
  but instead, just change the logic to do the enable and disable
  in place when the SOFT_MODE is set or cleared.

- Several kernel-doc fixes

- Removal of unused external declarations

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace/urgent

Head SHA1: dea499781a1150d285c62b26659f62fb00824fce


Gaosheng Cui (4):
      ring-buffer: Fix kernel-doc warnings in ring_buffer.c
      tracing/synthetic: Fix kernel-doc warnings in trace_events_synth.c
      tracing: Fix kernel-doc warnings in trace_events_trigger.c
      tracing: Fix kernel-doc warnings in trace_seq.c

YueHaibing (1):
      ftrace: Remove unused extern declarations

Zheng Yejian (2):
      ring-buffer: Fix wrong stat of cpu_buffer->read
      tracing: Fix warning in trace_buffered_event_disable()

----
 include/linux/ftrace.h              |  4 ----
 kernel/trace/ring_buffer.c          | 25 +++++++++++++------------
 kernel/trace/trace_events.c         | 14 ++++----------
 kernel/trace/trace_events_synth.c   |  1 +
 kernel/trace/trace_events_trigger.c |  2 ++
 kernel/trace/trace_seq.c            |  1 +
 6 files changed, 21 insertions(+), 26 deletions(-)

[for-linus][PATCH 1/7] ring-buffer: Fix wrong stat of cpu_buffer->read

[Steven Rostedt]

From: Zheng Yejian <zhengyejian1@huawei.com>

When pages are removed in rb_remove_pages(), 'cpu_buffer->read' is set
to 0 in order to make sure any read iterators reset themselves. However,
this will mess 'entries' stating, see following steps:

  # cd /sys/kernel/tracing/
  # 1. Enlarge ring buffer prepare for later reducing:
  # echo 20 > per_cpu/cpu0/buffer_size_kb
  # 2. Write a log into ring buffer of cpu0:
  # taskset -c 0 echo "hello1" > trace_marker
  # 3. Read the log:
  # cat per_cpu/cpu0/trace_pipe
       <...>-332     [000] .....    62.406844: tracing_mark_write: hello1
  # 4. Stop reading and see the stats, now 0 entries, and 1 event readed:
  # cat per_cpu/cpu0/stats
   entries: 0
   [...]
   read events: 1
  # 5. Reduce the ring buffer
  # echo 7 > per_cpu/cpu0/buffer_size_kb
  # 6. Now entries became unexpected 1 because actually no entries!!!
  # cat per_cpu/cpu0/stats
   entries: 1
   [...]
   read events: 0

To fix it, introduce 'page_removed' field to count total removed pages
since last reset, then use it to let read iterators reset themselves
instead of changing the 'read' pointer.

Link: https://lore.kernel.org/linux-trace-kernel/20230724054040.3489499-1-zhengyejian1@huawei.com

Cc: <mhiramat@kernel.org>
Cc: <vnagarnaik@google.com>
Fixes: 83f40318dab0 ("ring-buffer: Make removal of ring buffer pages atomic")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ring_buffer.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index de061dd47313..46b4a3c7c3bf 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -523,6 +523,8 @@ struct ring_buffer_per_cpu {
 	rb_time_t			before_stamp;
 	u64				event_stamp[MAX_NEST];
 	u64				read_stamp;
+	/* pages removed since last reset */
+	unsigned long			pages_removed;
 	/* ring buffer pages to update, > 0 to add, < 0 to remove */
 	long				nr_pages_to_update;
 	struct list_head		new_pages; /* new pages to add */
@@ -559,6 +561,7 @@ struct ring_buffer_iter {
 	struct buffer_page		*head_page;
 	struct buffer_page		*cache_reader_page;
 	unsigned long			cache_read;
+	unsigned long			cache_pages_removed;
 	u64				read_stamp;
 	u64				page_stamp;
 	struct ring_buffer_event	*event;
@@ -1957,6 +1960,8 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages)
 		to_remove = rb_list_head(to_remove)->next;
 		head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD;
 	}
+	/* Read iterators need to reset themselves when some pages removed */
+	cpu_buffer->pages_removed += nr_removed;
 
 	next_page = rb_list_head(to_remove)->next;
 
@@ -1978,12 +1983,6 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages)
 		cpu_buffer->head_page = list_entry(next_page,
 						struct buffer_page, list);
 
-	/*
-	 * change read pointer to make sure any read iterators reset
-	 * themselves
-	 */
-	cpu_buffer->read = 0;
-
 	/* pages are removed, resume tracing and then free the pages */
 	atomic_dec(&cpu_buffer->record_disabled);
 	raw_spin_unlock_irq(&cpu_buffer->reader_lock);
@@ -4395,6 +4394,7 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
 
 	iter->cache_reader_page = iter->head_page;
 	iter->cache_read = cpu_buffer->read;
+	iter->cache_pages_removed = cpu_buffer->pages_removed;
 
 	if (iter->head) {
 		iter->read_stamp = cpu_buffer->read_stamp;
@@ -4849,12 +4849,13 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 	buffer = cpu_buffer->buffer;
 
 	/*
-	 * Check if someone performed a consuming read to
-	 * the buffer. A consuming read invalidates the iterator
-	 * and we need to reset the iterator in this case.
+	 * Check if someone performed a consuming read to the buffer
+	 * or removed some pages from the buffer. In these cases,
+	 * iterator was invalidated and we need to reset it.
 	 */
 	if (unlikely(iter->cache_read != cpu_buffer->read ||
-		     iter->cache_reader_page != cpu_buffer->reader_page))
+		     iter->cache_reader_page != cpu_buffer->reader_page ||
+		     iter->cache_pages_removed != cpu_buffer->pages_removed))
 		rb_iter_reset(iter);
 
  again:
@@ -5298,6 +5299,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 	cpu_buffer->last_overrun = 0;
 
 	rb_head_page_activate(cpu_buffer);
+	cpu_buffer->pages_removed = 0;
 }
 
 /* Must have disabled the cpu buffer then done a synchronize_rcu */
-- 
2.40.1

[for-linus][PATCH 2/7] ring-buffer: Fix kernel-doc warnings in ring_buffer.c

[Steven Rostedt]

From: Gaosheng Cui <cuigaosheng1@huawei.com>

Fix kernel-doc warnings:

kernel/trace/ring_buffer.c:954: warning: Function parameter or
member 'cpu' not described in 'ring_buffer_wake_waiters'
kernel/trace/ring_buffer.c:3383: warning: Excess function parameter
'event' description in 'ring_buffer_unlock_commit'
kernel/trace/ring_buffer.c:5359: warning: Excess function parameter
'cpu' description in 'ring_buffer_reset_online_cpus'

Link: https://lkml.kernel.org/r/20230724140827.1023266-2-cuigaosheng1@huawei.com

Cc: <mhiramat@kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ring_buffer.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 46b4a3c7c3bf..52dea5dd5362 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -950,6 +950,7 @@ static void rb_wake_up_waiters(struct irq_work *work)
 /**
  * ring_buffer_wake_waiters - wake up any waiters on this ring buffer
  * @buffer: The ring buffer to wake waiters on
+ * @cpu: The CPU buffer to wake waiters on
  *
  * In the case of a file that represents a ring buffer is closing,
  * it is prudent to wake up any waiters that are on this.
@@ -3375,7 +3376,6 @@ void ring_buffer_nest_end(struct trace_buffer *buffer)
 /**
  * ring_buffer_unlock_commit - commit a reserved
  * @buffer: The buffer to commit to
- * @event: The event pointer to commit.
  *
  * This commits the data to the ring buffer, and releases any locks held.
  *
@@ -5358,7 +5358,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
 /**
  * ring_buffer_reset_online_cpus - reset a ring buffer per CPU buffer
  * @buffer: The ring buffer to reset a per cpu buffer of
- * @cpu: The CPU buffer to be reset
  */
 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
 {
-- 
2.40.1

[for-linus][PATCH 3/7] tracing/synthetic: Fix kernel-doc warnings in trace_events_synth.c

[Steven Rostedt]

From: Gaosheng Cui <cuigaosheng1@huawei.com>

Fix kernel-doc warning:

kernel/trace/trace_events_synth.c:1257: warning: Function parameter
or member 'mod' not described in 'synth_event_gen_cmd_array_start'

Link: https://lkml.kernel.org/r/20230724140827.1023266-3-cuigaosheng1@huawei.com

Cc: <mhiramat@kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_synth.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index d6a70aff2410..dd398afc8e25 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -1230,6 +1230,7 @@ EXPORT_SYMBOL_GPL(__synth_event_gen_cmd_start);
  * synth_event_gen_cmd_array_start - Start synthetic event command from an array
  * @cmd: A pointer to the dynevent_cmd struct representing the new event
  * @name: The name of the synthetic event
+ * @mod: The module creating the event, NULL if not created from a module
  * @fields: An array of type/name field descriptions
  * @n_fields: The number of field descriptions contained in the fields array
  *
-- 
2.40.1

[for-linus][PATCH 4/7] tracing: Fix kernel-doc warnings in trace_events_trigger.c

[Steven Rostedt]

From: Gaosheng Cui <cuigaosheng1@huawei.com>

Fix kernel-doc warnings:

kernel/trace/trace_events_trigger.c:59: warning: Function parameter
or member 'buffer' not described in 'event_triggers_call'
kernel/trace/trace_events_trigger.c:59: warning: Function parameter
or member 'event' not described in 'event_triggers_call'

Link: https://lkml.kernel.org/r/20230724140827.1023266-4-cuigaosheng1@huawei.com

Cc: <mhiramat@kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_trigger.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index e535959939d3..46439e3bcec4 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -31,7 +31,9 @@ void trigger_data_free(struct event_trigger_data *data)
 /**
  * event_triggers_call - Call triggers associated with a trace event
  * @file: The trace_event_file associated with the event
+ * @buffer: The ring buffer that the event is being written to
  * @rec: The trace entry for the event, NULL for unconditional invocation
+ * @event: The event meta data in the ring buffer
  *
  * For each trigger associated with an event, invoke the trigger
  * function registered with the associated trigger command.  If rec is
-- 
2.40.1

[for-linus][PATCH 5/7] tracing: Fix kernel-doc warnings in trace_seq.c

[Steven Rostedt]

From: Gaosheng Cui <cuigaosheng1@huawei.com>

Fix kernel-doc warning:

kernel/trace/trace_seq.c:142: warning: Function parameter or member
'args' not described in 'trace_seq_vprintf'

Link: https://lkml.kernel.org/r/20230724140827.1023266-5-cuigaosheng1@huawei.com

Cc: <mhiramat@kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_seq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index e5e299260d0c..bac06ee3b98b 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -131,6 +131,7 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask);
  * trace_seq_vprintf - sequence printing of trace information
  * @s: trace sequence descriptor
  * @fmt: printf format string
+ * @args: Arguments for the format string
  *
  * The tracer may use either sequence operations or its own
  * copy to user routines. To simplify formatting of a trace
-- 
2.40.1

[for-linus][PATCH 6/7] ftrace: Remove unused extern declarations

[Steven Rostedt]

From: YueHaibing <yuehaibing@huawei.com>

commit 6a9c981b1e96 ("ftrace: Remove unused function ftrace_arch_read_dyn_info()")
left ftrace_arch_read_dyn_info() extern declaration.
And commit 1d74f2a0f64b ("ftrace: remove ftrace_ip_converted()")
leave ftrace_ip_converted() declaration.

Link: https://lore.kernel.org/linux-trace-kernel/20230725134808.9716-1-yuehaibing@huawei.com

Cc: <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/linux/ftrace.h | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ce156c7704ee..aad9cf8876b5 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -684,7 +684,6 @@ void __init
 ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable);
 
 /* defined in arch */
-extern int ftrace_ip_converted(unsigned long ip);
 extern int ftrace_dyn_arch_init(void);
 extern void ftrace_replace_code(int enable);
 extern int ftrace_update_ftrace_func(ftrace_func_t func);
@@ -859,9 +858,6 @@ static inline int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_a
 }
 #endif
 
-/* May be defined in arch */
-extern int ftrace_arch_read_dyn_info(char *buf, int size);
-
 extern int skip_trace(unsigned long ip);
 extern void ftrace_module_init(struct module *mod);
 extern void ftrace_module_enable(struct module *mod);
-- 
2.40.1

[for-linus][PATCH 7/7] tracing: Fix warning in trace_buffered_event_disable()

[Steven Rostedt]

From: Zheng Yejian <zhengyejian1@huawei.com>

Warning happened in trace_buffered_event_disable() at
  WARN_ON_ONCE(!trace_buffered_event_ref)

  Call Trace:
   ? __warn+0xa5/0x1b0
   ? trace_buffered_event_disable+0x189/0x1b0
   __ftrace_event_enable_disable+0x19e/0x3e0
   free_probe_data+0x3b/0xa0
   unregister_ftrace_function_probe_func+0x6b8/0x800
   event_enable_func+0x2f0/0x3d0
   ftrace_process_regex.isra.0+0x12d/0x1b0
   ftrace_filter_write+0xe6/0x140
   vfs_write+0x1c9/0x6f0
   [...]

The cause of the warning is in __ftrace_event_enable_disable(),
trace_buffered_event_enable() was called once while
trace_buffered_event_disable() was called twice.
Reproduction script show as below, for analysis, see the comments:
 ```
 #!/bin/bash

 cd /sys/kernel/tracing/

 # 1. Register a 'disable_event' command, then:
 #    1) SOFT_DISABLED_BIT was set;
 #    2) trace_buffered_event_enable() was called first time;
 echo 'cmdline_proc_show:disable_event:initcall:initcall_finish' > \
     set_ftrace_filter

 # 2. Enable the event registered, then:
 #    1) SOFT_DISABLED_BIT was cleared;
 #    2) trace_buffered_event_disable() was called first time;
 echo 1 > events/initcall/initcall_finish/enable

 # 3. Try to call into cmdline_proc_show(), then SOFT_DISABLED_BIT was
 #    set again!!!
 cat /proc/cmdline

 # 4. Unregister the 'disable_event' command, then:
 #    1) SOFT_DISABLED_BIT was cleared again;
 #    2) trace_buffered_event_disable() was called second time!!!
 echo '!cmdline_proc_show:disable_event:initcall:initcall_finish' > \
     set_ftrace_filter
 ```

To fix it, IIUC, we can change to call trace_buffered_event_enable() at
fist time soft-mode enabled, and call trace_buffered_event_disable() at
last time soft-mode disabled.

Link: https://lore.kernel.org/linux-trace-kernel/20230726095804.920457-1-zhengyejian1@huawei.com

Cc: <mhiramat@kernel.org>
Fixes: 0fc1b09ff1ff ("tracing: Use temp buffer when filtering events")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 5d6ae4eae510..578f1f7d49a6 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -611,7 +611,6 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 {
 	struct trace_event_call *call = file->event_call;
 	struct trace_array *tr = file->tr;
-	unsigned long file_flags = file->flags;
 	int ret = 0;
 	int disable;
 
@@ -635,6 +634,8 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 				break;
 			disable = file->flags & EVENT_FILE_FL_SOFT_DISABLED;
 			clear_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags);
+			/* Disable use of trace_buffered_event */
+			trace_buffered_event_disable();
 		} else
 			disable = !(file->flags & EVENT_FILE_FL_SOFT_MODE);
 
@@ -673,6 +674,8 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 			if (atomic_inc_return(&file->sm_ref) > 1)
 				break;
 			set_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags);
+			/* Enable use of trace_buffered_event */
+			trace_buffered_event_enable();
 		}
 
 		if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
@@ -712,15 +715,6 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		break;
 	}
 
-	/* Enable or disable use of trace_buffered_event */
-	if ((file_flags & EVENT_FILE_FL_SOFT_DISABLED) !=
-	    (file->flags & EVENT_FILE_FL_SOFT_DISABLED)) {
-		if (file->flags & EVENT_FILE_FL_SOFT_DISABLED)
-			trace_buffered_event_enable();
-		else
-			trace_buffered_event_disable();
-	}
-
 	return ret;
 }
 
-- 
2.40.1