[for-next][PATCH 0/5] ftrace: Updates for 6.14

[for-next][PATCH 0/5] ftrace: Updates for 6.14

[Steven Rostedt]

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
ftrace/for-next

Head SHA1: d576aec24df9f58ed0ebe2ff854daafe837f0225


Masami Hiramatsu (Google) (1):
      fgraph: Get ftrace recursion lock in function_graph_enter

Steven Rostedt (4):
      fgraph: Remove unnecessary disabling of interrupts and recursion
      ftrace: Do not disable interrupts in profiler
      ftrace: Remove unneeded goto jumps
      ftrace: Switch ftrace.c code over to use guard()

----
 arch/powerpc/kernel/trace/ftrace.c       |   6 --
 arch/powerpc/kernel/trace/ftrace_64_pg.c |   6 --
 arch/x86/kernel/ftrace.c                 |   7 --
 kernel/trace/fgraph.c                    |   8 +-
 kernel/trace/ftrace.c                    | 130 +++++++++++--------------------
 kernel/trace/trace_functions_graph.c     |  37 ++++-----
 6 files changed, 67 insertions(+), 127 deletions(-)

[for-next][PATCH 1/5] fgraph: Remove unnecessary disabling of interrupts and recursion

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

The function graph tracer disables interrupts as well as prevents
recursion via NMIs when recording the graph tracer code. There's no reason
to do this today. That disabling goes back to 2008 when the function graph
tracer was first introduced and recursion protection wasn't part of the
code.

Today, there's no reason to disable interrupts or prevent the code from
recursing as the infrastructure can easily handle it.

Before this change:

~# echo function_graph > /sys/kernel/tracing/current_tracer
~# perf stat -r 10 ./hackbench 10
Time: 4.240
Time: 4.236
Time: 4.106
Time: 4.014
Time: 4.314
Time: 3.830
Time: 4.063
Time: 4.323
Time: 3.763
Time: 3.727

 Performance counter stats for '/work/c/hackbench 10' (10 runs):

         33,937.20 msec task-clock                       #    7.008 CPUs utilized               ( +-  1.85% )
            18,220      context-switches                 #  536.874 /sec                        ( +-  6.41% )
               624      cpu-migrations                   #   18.387 /sec                        ( +-  9.07% )
            11,319      page-faults                      #  333.528 /sec                        ( +-  1.97% )
    76,657,643,617      cycles                           #    2.259 GHz                         ( +-  0.40% )
   141,403,302,768      instructions                     #    1.84  insn per cycle              ( +-  0.37% )
    25,518,463,888      branches                         #  751.932 M/sec                       ( +-  0.35% )
       156,151,050      branch-misses                    #    0.61% of all branches             ( +-  0.63% )

            4.8423 +- 0.0892 seconds time elapsed  ( +-  1.84% )

After this change:

~# echo function_graph > /sys/kernel/tracing/current_tracer
~# perf stat -r 10 ./hackbench 10
Time: 3.340
Time: 3.192
Time: 3.129
Time: 2.579
Time: 2.589
Time: 2.798
Time: 2.791
Time: 2.955
Time: 3.044
Time: 3.065

 Performance counter stats for './hackbench 10' (10 runs):

         24,416.30 msec task-clock                       #    6.996 CPUs utilized               ( +-  2.74% )
            16,764      context-switches                 #  686.590 /sec                        ( +-  5.85% )
               469      cpu-migrations                   #   19.208 /sec                        ( +-  6.14% )
            11,519      page-faults                      #  471.775 /sec                        ( +-  1.92% )
    53,895,628,450      cycles                           #    2.207 GHz                         ( +-  0.52% )
   105,552,664,638      instructions                     #    1.96  insn per cycle              ( +-  0.47% )
    17,808,672,667      branches                         #  729.376 M/sec                       ( +-  0.48% )
       133,075,435      branch-misses                    #    0.75% of all branches             ( +-  0.59% )

             3.490 +- 0.112 seconds time elapsed  ( +-  3.22% )

Also removed unneeded "unlikely()" around the retaddr code.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20241223184941.204074053@goodmis.org
Fixes: 9cd2992f2d6c8 ("fgraph: Have set_graph_notrace only affect function_graph tracer") # Performance only
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_functions_graph.c | 37 +++++++++++-----------------
 1 file changed, 15 insertions(+), 22 deletions(-)

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 5504b5e4e7b4..f513603d7df9 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -181,10 +181,9 @@ int trace_graph_entry(struct ftrace_graph_ent *trace,
 	struct trace_array *tr = gops->private;
 	struct trace_array_cpu *data;
 	struct fgraph_times *ftimes;
-	unsigned long flags;
 	unsigned int trace_ctx;
 	long disabled;
-	int ret;
+	int ret = 0;
 	int cpu;
 
 	if (*task_var & TRACE_GRAPH_NOTRACE)
@@ -235,25 +234,21 @@ int trace_graph_entry(struct ftrace_graph_ent *trace,
 	if (tracing_thresh)
 		return 1;
 
-	local_irq_save(flags);
+	preempt_disable_notrace();
 	cpu = raw_smp_processor_id();
 	data = per_cpu_ptr(tr->array_buffer.data, cpu);
-	disabled = atomic_inc_return(&data->disabled);
-	if (likely(disabled == 1)) {
-		trace_ctx = tracing_gen_ctx_flags(flags);
-		if (unlikely(IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) &&
-			tracer_flags_is_set(TRACE_GRAPH_PRINT_RETADDR))) {
+	disabled = atomic_read(&data->disabled);
+	if (likely(!disabled)) {
+		trace_ctx = tracing_gen_ctx();
+		if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) &&
+		    tracer_flags_is_set(TRACE_GRAPH_PRINT_RETADDR)) {
 			unsigned long retaddr = ftrace_graph_top_ret_addr(current);
-
 			ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx, retaddr);
-		} else
+		} else {
 			ret = __trace_graph_entry(tr, trace, trace_ctx);
-	} else {
-		ret = 0;
+		}
 	}
-
-	atomic_dec(&data->disabled);
-	local_irq_restore(flags);
+	preempt_enable_notrace();
 
 	return ret;
 }
@@ -320,7 +315,6 @@ void trace_graph_return(struct ftrace_graph_ret *trace,
 	struct trace_array *tr = gops->private;
 	struct trace_array_cpu *data;
 	struct fgraph_times *ftimes;
-	unsigned long flags;
 	unsigned int trace_ctx;
 	long disabled;
 	int size;
@@ -341,16 +335,15 @@ void trace_graph_return(struct ftrace_graph_ret *trace,
 
 	trace->calltime = ftimes->calltime;
 
-	local_irq_save(flags);
+	preempt_disable_notrace();
 	cpu = raw_smp_processor_id();
 	data = per_cpu_ptr(tr->array_buffer.data, cpu);
-	disabled = atomic_inc_return(&data->disabled);
-	if (likely(disabled == 1)) {
-		trace_ctx = tracing_gen_ctx_flags(flags);
+	disabled = atomic_read(&data->disabled);
+	if (likely(!disabled)) {
+		trace_ctx = tracing_gen_ctx();
 		__trace_graph_return(tr, trace, trace_ctx);
 	}
-	atomic_dec(&data->disabled);
-	local_irq_restore(flags);
+	preempt_enable_notrace();
 }
 
 static void trace_graph_thresh_return(struct ftrace_graph_ret *trace,
-- 
2.45.2

[for-next][PATCH 2/5] ftrace: Do not disable interrupts in profiler

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

The function profiler disables interrupts before processing. This was
there since the profiler was introduced back in 2009 when there were
recursion issues to deal with. The function tracer is much more robust
today and has its own internal recursion protection. There's no reason to
disable interrupts in the function profiler.

Instead, just disable preemption and use the guard() infrastructure while
at it.

Before this change:

~# echo 1 > /sys/kernel/tracing/function_profile_enabled
~# perf stat -r 10 ./hackbench 10
Time: 3.099
Time: 2.556
Time: 2.500
Time: 2.705
Time: 2.985
Time: 2.959
Time: 2.859
Time: 2.621
Time: 2.742
Time: 2.631

 Performance counter stats for '/work/c/hackbench 10' (10 runs):

         23,156.77 msec task-clock                       #    6.951 CPUs utilized               ( +-  2.36% )
            18,306      context-switches                 #  790.525 /sec                        ( +-  5.95% )
               495      cpu-migrations                   #   21.376 /sec                        ( +-  8.61% )
            11,522      page-faults                      #  497.565 /sec                        ( +-  1.80% )
    47,967,124,606      cycles                           #    2.071 GHz                         ( +-  0.41% )
    80,009,078,371      instructions                     #    1.67  insn per cycle              ( +-  0.34% )
    16,389,249,798      branches                         #  707.752 M/sec                       ( +-  0.36% )
       139,943,109      branch-misses                    #    0.85% of all branches             ( +-  0.61% )

             3.332 +- 0.101 seconds time elapsed  ( +-  3.04% )

After this change:

~# echo 1 > /sys/kernel/tracing/function_profile_enabled
~# perf stat -r 10 ./hackbench 10
Time: 1.869
Time: 1.428
Time: 1.575
Time: 1.569
Time: 1.685
Time: 1.511
Time: 1.611
Time: 1.672
Time: 1.724
Time: 1.715

 Performance counter stats for '/work/c/hackbench 10' (10 runs):

         13,578.21 msec task-clock                       #    6.931 CPUs utilized               ( +-  2.23% )
            12,736      context-switches                 #  937.973 /sec                        ( +-  3.86% )
               341      cpu-migrations                   #   25.114 /sec                        ( +-  5.27% )
            11,378      page-faults                      #  837.960 /sec                        ( +-  1.74% )
    27,638,039,036      cycles                           #    2.035 GHz                         ( +-  0.27% )
    45,107,762,498      instructions                     #    1.63  insn per cycle              ( +-  0.23% )
     8,623,868,018      branches                         #  635.125 M/sec                       ( +-  0.27% )
       125,738,443      branch-misses                    #    1.46% of all branches             ( +-  0.32% )

            1.9590 +- 0.0484 seconds time elapsed  ( +-  2.47% )

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20241223184941.373853944@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9b17efb1a87d..63a9ffa65e17 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -789,27 +789,24 @@ function_profile_call(unsigned long ip, unsigned long parent_ip,
 {
 	struct ftrace_profile_stat *stat;
 	struct ftrace_profile *rec;
-	unsigned long flags;
 
 	if (!ftrace_profile_enabled)
 		return;
 
-	local_irq_save(flags);
+	guard(preempt_notrace)();
 
 	stat = this_cpu_ptr(&ftrace_profile_stats);
 	if (!stat->hash || !ftrace_profile_enabled)
-		goto out;
+		return;
 
 	rec = ftrace_find_profiled_func(stat, ip);
 	if (!rec) {
 		rec = ftrace_profile_alloc(stat, ip);
 		if (!rec)
-			goto out;
+			return;
 	}
 
 	rec->counter++;
- out:
-	local_irq_restore(flags);
 }
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -856,19 +853,19 @@ static void profile_graph_return(struct ftrace_graph_ret *trace,
 	unsigned long long calltime;
 	unsigned long long rettime = trace_clock_local();
 	struct ftrace_profile *rec;
-	unsigned long flags;
 	int size;
 
-	local_irq_save(flags);
+	guard(preempt_notrace)();
+
 	stat = this_cpu_ptr(&ftrace_profile_stats);
 	if (!stat->hash || !ftrace_profile_enabled)
-		goto out;
+		return;
 
 	profile_data = fgraph_retrieve_data(gops->idx, &size);
 
 	/* If the calltime was zero'd ignore it */
 	if (!profile_data || !profile_data->calltime)
-		goto out;
+		return;
 
 	calltime = rettime - profile_data->calltime;
 
@@ -896,9 +893,6 @@ static void profile_graph_return(struct ftrace_graph_ret *trace,
 		rec->time += calltime;
 		rec->time_squared += calltime * calltime;
 	}
-
- out:
-	local_irq_restore(flags);
 }
 
 static struct fgraph_ops fprofiler_ops = {
-- 
2.45.2

[for-next][PATCH 3/5] ftrace: Remove unneeded goto jumps

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

There are some goto jumps to exit a program to just return a value. The
code after the label doesn't free anything nor does it do any unlocks. It
simply returns the variable that was set before the jump.

Remove these unneeded goto jumps.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20241223184941.544855549@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 63a9ffa65e17..2c1691aa1d2f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1669,14 +1669,12 @@ unsigned long ftrace_location(unsigned long ip)
 	loc = ftrace_location_range(ip, ip);
 	if (!loc) {
 		if (!kallsyms_lookup_size_offset(ip, &size, &offset))
-			goto out;
+			return 0;
 
 		/* map sym+0 to __fentry__ */
 		if (!offset)
 			loc = ftrace_location_range(ip, ip + size - 1);
 	}
-
-out:
 	return loc;
 }
 
@@ -2071,7 +2069,7 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops,
 			continue;
 
 		if (rec == end)
-			goto err_out;
+			return -EBUSY;
 
 		in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
 		in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
@@ -2084,7 +2082,6 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops,
 			rec->flags |= FTRACE_FL_IPMODIFY;
 	} while_for_each_ftrace_rec();
 
-err_out:
 	return -EBUSY;
 }
 
@@ -5720,12 +5717,10 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
 					   parser->idx, enable);
 		trace_parser_clear(parser);
 		if (ret < 0)
-			goto out;
+			return ret;
 	}
 
-	ret = read;
- out:
-	return ret;
+	return read;
 }
 
 ssize_t
-- 
2.45.2

[for-next][PATCH 4/5] ftrace: Switch ftrace.c code over to use guard()

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

There are a few functions in ftrace.c that have "goto out" or equivalent
on error in order to release locks that were taken. This can be error
prone or just simply make the code more complex.

Switch every location that ends with unlocking a mutex on error over to
using the guard(mutex)() infrastructure to let the compiler worry about
releasing locks. This makes the code easier to read and understand.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20241223184941.718001540@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 97 +++++++++++++++----------------------------
 1 file changed, 34 insertions(+), 63 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 2c1691aa1d2f..6ebc76bafd38 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -536,24 +536,21 @@ static int function_stat_show(struct seq_file *m, void *v)
 {
 	struct ftrace_profile *rec = v;
 	char str[KSYM_SYMBOL_LEN];
-	int ret = 0;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	static struct trace_seq s;
 	unsigned long long avg;
 	unsigned long long stddev;
 #endif
-	mutex_lock(&ftrace_profile_lock);
+	guard(mutex)(&ftrace_profile_lock);
 
 	/* we raced with function_profile_reset() */
-	if (unlikely(rec->counter == 0)) {
-		ret = -EBUSY;
-		goto out;
-	}
+	if (unlikely(rec->counter == 0))
+		return -EBUSY;
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	avg = div64_ul(rec->time, rec->counter);
 	if (tracing_thresh && (avg < tracing_thresh))
-		goto out;
+		return 0;
 #endif
 
 	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
@@ -590,10 +587,8 @@ static int function_stat_show(struct seq_file *m, void *v)
 	trace_print_seq(m, &s);
 #endif
 	seq_putc(m, '\n');
-out:
-	mutex_unlock(&ftrace_profile_lock);
 
-	return ret;
+	return 0;
 }
 
 static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
@@ -944,20 +939,16 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
 
 	val = !!val;
 
-	mutex_lock(&ftrace_profile_lock);
+	guard(mutex)(&ftrace_profile_lock);
 	if (ftrace_profile_enabled ^ val) {
 		if (val) {
 			ret = ftrace_profile_init();
-			if (ret < 0) {
-				cnt = ret;
-				goto out;
-			}
+			if (ret < 0)
+				return ret;
 
 			ret = register_ftrace_profiler();
-			if (ret < 0) {
-				cnt = ret;
-				goto out;
-			}
+			if (ret < 0)
+				return ret;
 			ftrace_profile_enabled = 1;
 		} else {
 			ftrace_profile_enabled = 0;
@@ -968,8 +959,6 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
 			unregister_ftrace_profiler();
 		}
 	}
- out:
-	mutex_unlock(&ftrace_profile_lock);
 
 	*ppos += cnt;
 
@@ -5610,20 +5599,15 @@ static DEFINE_MUTEX(ftrace_cmd_mutex);
 __init int register_ftrace_command(struct ftrace_func_command *cmd)
 {
 	struct ftrace_func_command *p;
-	int ret = 0;
 
-	mutex_lock(&ftrace_cmd_mutex);
+	guard(mutex)(&ftrace_cmd_mutex);
 	list_for_each_entry(p, &ftrace_commands, list) {
-		if (strcmp(cmd->name, p->name) == 0) {
-			ret = -EBUSY;
-			goto out_unlock;
-		}
+		if (strcmp(cmd->name, p->name) == 0)
+			return -EBUSY;
 	}
 	list_add(&cmd->list, &ftrace_commands);
- out_unlock:
-	mutex_unlock(&ftrace_cmd_mutex);
 
-	return ret;
+	return 0;
 }
 
 /*
@@ -5633,20 +5617,17 @@ __init int register_ftrace_command(struct ftrace_func_command *cmd)
 __init int unregister_ftrace_command(struct ftrace_func_command *cmd)
 {
 	struct ftrace_func_command *p, *n;
-	int ret = -ENODEV;
 
-	mutex_lock(&ftrace_cmd_mutex);
+	guard(mutex)(&ftrace_cmd_mutex);
+
 	list_for_each_entry_safe(p, n, &ftrace_commands, list) {
 		if (strcmp(cmd->name, p->name) == 0) {
-			ret = 0;
 			list_del_init(&p->list);
-			goto out_unlock;
+			return 0;
 		}
 	}
- out_unlock:
-	mutex_unlock(&ftrace_cmd_mutex);
 
-	return ret;
+	return -ENODEV;
 }
 
 static int ftrace_process_regex(struct ftrace_iterator *iter,
@@ -5656,7 +5637,7 @@ static int ftrace_process_regex(struct ftrace_iterator *iter,
 	struct trace_array *tr = iter->ops->private;
 	char *func, *command, *next = buff;
 	struct ftrace_func_command *p;
-	int ret = -EINVAL;
+	int ret;
 
 	func = strsep(&next, ":");
 
@@ -5673,17 +5654,14 @@ static int ftrace_process_regex(struct ftrace_iterator *iter,
 
 	command = strsep(&next, ":");
 
-	mutex_lock(&ftrace_cmd_mutex);
+	guard(mutex)(&ftrace_cmd_mutex);
+
 	list_for_each_entry(p, &ftrace_commands, list) {
-		if (strcmp(p->name, command) == 0) {
-			ret = p->func(tr, hash, func, command, next, enable);
-			goto out_unlock;
-		}
+		if (strcmp(p->name, command) == 0)
+			return p->func(tr, hash, func, command, next, enable);
 	}
- out_unlock:
-	mutex_unlock(&ftrace_cmd_mutex);
 
-	return ret;
+	return -EINVAL;
 }
 
 static ssize_t
@@ -8280,7 +8258,7 @@ pid_write(struct file *filp, const char __user *ubuf,
 	if (!cnt)
 		return 0;
 
-	mutex_lock(&ftrace_lock);
+	guard(mutex)(&ftrace_lock);
 
 	switch (type) {
 	case TRACE_PIDS:
@@ -8296,14 +8274,13 @@ pid_write(struct file *filp, const char __user *ubuf,
 					     lockdep_is_held(&ftrace_lock));
 		break;
 	default:
-		ret = -EINVAL;
 		WARN_ON_ONCE(1);
-		goto out;
+		return -EINVAL;
 	}
 
 	ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt);
 	if (ret < 0)
-		goto out;
+		return ret;
 
 	switch (type) {
 	case TRACE_PIDS:
@@ -8332,11 +8309,8 @@ pid_write(struct file *filp, const char __user *ubuf,
 
 	ftrace_update_pid_func();
 	ftrace_startup_all(0);
- out:
-	mutex_unlock(&ftrace_lock);
 
-	if (ret > 0)
-		*ppos += ret;
+	*ppos += ret;
 
 	return ret;
 }
@@ -8739,17 +8713,17 @@ static int
 ftrace_enable_sysctl(const struct ctl_table *table, int write,
 		     void *buffer, size_t *lenp, loff_t *ppos)
 {
-	int ret = -ENODEV;
+	int ret;
 
-	mutex_lock(&ftrace_lock);
+	guard(mutex)(&ftrace_lock);
 
 	if (unlikely(ftrace_disabled))
-		goto out;
+		return -ENODEV;
 
 	ret = proc_dointvec(table, write, buffer, lenp, ppos);
 
 	if (ret || !write || (last_ftrace_enabled == !!ftrace_enabled))
-		goto out;
+		return ret;
 
 	if (ftrace_enabled) {
 
@@ -8763,8 +8737,7 @@ ftrace_enable_sysctl(const struct ctl_table *table, int write,
 	} else {
 		if (is_permanent_ops_registered()) {
 			ftrace_enabled = true;
-			ret = -EBUSY;
-			goto out;
+			return -EBUSY;
 		}
 
 		/* stopping ftrace calls (just send to ftrace_stub) */
@@ -8774,9 +8747,7 @@ ftrace_enable_sysctl(const struct ctl_table *table, int write,
 	}
 
 	last_ftrace_enabled = !!ftrace_enabled;
- out:
-	mutex_unlock(&ftrace_lock);
-	return ret;
+	return 0;
 }
 
 static struct ctl_table ftrace_sysctls[] = {
-- 
2.45.2

[for-next][PATCH 5/5] fgraph: Get ftrace recursion lock in function_graph_enter

[Steven Rostedt]

From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>

Get the ftrace recursion lock in the generic function_graph_enter()
instead of each architecture code.
This changes all function_graph tracer callbacks running in
non-preemptive state. On x86 and powerpc, this is by default, but
on the other architecutres, this will be new.

Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/173379653720.973433.18438622234884980494.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 arch/powerpc/kernel/trace/ftrace.c       | 6 ------
 arch/powerpc/kernel/trace/ftrace_64_pg.c | 6 ------
 arch/x86/kernel/ftrace.c                 | 7 -------
 kernel/trace/fgraph.c                    | 8 +++++++-
 4 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 5ccd791761e8..e41daf2c4a31 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -658,7 +658,6 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	unsigned long sp = arch_ftrace_regs(fregs)->regs.gpr[1];
-	int bit;
 
 	if (unlikely(ftrace_graph_is_dead()))
 		goto out;
@@ -666,14 +665,9 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		goto out;
 
-	bit = ftrace_test_recursion_trylock(ip, parent_ip);
-	if (bit < 0)
-		goto out;
-
 	if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
 		parent_ip = ppc_function_entry(return_to_handler);
 
-	ftrace_test_recursion_unlock(bit);
 out:
 	arch_ftrace_regs(fregs)->regs.link = parent_ip;
 }
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c b/arch/powerpc/kernel/trace/ftrace_64_pg.c
index 98787376eb87..8fb860b90ae1 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.c
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c
@@ -790,7 +790,6 @@ static unsigned long
 __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
 {
 	unsigned long return_hooker;
-	int bit;
 
 	if (unlikely(ftrace_graph_is_dead()))
 		goto out;
@@ -798,16 +797,11 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		goto out;
 
-	bit = ftrace_test_recursion_trylock(ip, parent);
-	if (bit < 0)
-		goto out;
-
 	return_hooker = ppc_function_entry(return_to_handler);
 
 	if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
 		parent = return_hooker;
 
-	ftrace_test_recursion_unlock(bit);
 out:
 	return parent;
 }
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 4dd0ad6c94d6..33f50c80f481 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -615,7 +615,6 @@ void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
 			   unsigned long frame_pointer)
 {
 	unsigned long return_hooker = (unsigned long)&return_to_handler;
-	int bit;
 
 	/*
 	 * When resuming from suspend-to-ram, this function can be indirectly
@@ -635,14 +634,8 @@ void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;
 
-	bit = ftrace_test_recursion_trylock(ip, *parent);
-	if (bit < 0)
-		return;
-
 	if (!function_graph_enter(*parent, ip, frame_pointer, parent))
 		*parent = return_hooker;
-
-	ftrace_test_recursion_unlock(bit);
 }
 
 #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index ddedcb50917f..5c68d6109119 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -650,8 +650,13 @@ int function_graph_enter(unsigned long ret, unsigned long func,
 	struct ftrace_graph_ent trace;
 	unsigned long bitmap = 0;
 	int offset;
+	int bit;
 	int i;
 
+	bit = ftrace_test_recursion_trylock(func, ret);
+	if (bit < 0)
+		return -EBUSY;
+
 	trace.func = func;
 	trace.depth = ++current->curr_ret_depth;
 
@@ -697,12 +702,13 @@ int function_graph_enter(unsigned long ret, unsigned long func,
 	 * flag, set that bit always.
 	 */
 	set_bitmap(current, offset, bitmap | BIT(0));
-
+	ftrace_test_recursion_unlock(bit);
 	return 0;
  out_ret:
 	current->curr_ret_stack -= FGRAPH_FRAME_OFFSET + 1;
  out:
 	current->curr_ret_depth--;
+	ftrace_test_recursion_unlock(bit);
 	return -EBUSY;
 }
 
-- 
2.45.2