tracing: Remove EVENT_FILE_FL_SOFT_MODE flag

When soft disabling of trace events was first created, it needed to have a
way to know if a file had a user that was using it with soft disabled (for
triggers that need to enable or disable events from a context that can not
really enable or disable the event, it would set SOFT_DISABLED to state it
is disabled). The flag SOFT_MODE was used to denote that an event had a
user that would enable or disable it via the SOFT_DISABLED flag.

Commit 1cf4c0732db3c ("tracing: Modify soft-mode only if there's no other
referrer") fixed a bug where if two users were using the SOFT_DISABLED
flag the accounting would get messed up as the SOFT_MODE flag could only
handle one user. That commit added the sm_ref counter which kept track of
how many users were using the event in "soft mode". This made the
SOFT_MODE flag redundant as it should only be set if the sm_ref counter is
non zero.

Remove the SOFT_MODE flag and just use the sm_ref counter to know the
event is in soft mode or not. This makes the code a bit simpler.

Link: https://lore.kernel.org/all/20250702111908.03759998@batman.local.home/

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Link: https://lore.kernel.org/20250702143657.18dd1882@batman.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 12 insertions, 12 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 120531268abf..0980f4def360 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -768,6 +768,7 @@ 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;
+	bool soft_mode = atomic_read(&file->sm_ref) != 0;
 	int ret = 0;
 	int disable;
 
@@ -782,7 +783,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		 * is set we do not want the event to be enabled before we
 		 * clear the bit.
 		 *
-		 * When soft_disable is not set but the SOFT_MODE flag is,
+		 * When soft_disable is not set but the soft_mode is,
 		 * we do nothing. Do not disable the tracepoint, otherwise
 		 * "soft enable"s (clearing the SOFT_DISABLED bit) wont work.
 		 */
@@ -790,11 +791,11 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 			if (atomic_dec_return(&file->sm_ref) > 0)
 				break;
 			disable = file->flags & EVENT_FILE_FL_SOFT_DISABLED;
-			clear_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags);
+			soft_mode = false;
 			/* Disable use of trace_buffered_event */
 			trace_buffered_event_disable();
 		} else
-			disable = !(file->flags & EVENT_FILE_FL_SOFT_MODE);
+			disable = !soft_mode;
 
 		if (disable && (file->flags & EVENT_FILE_FL_ENABLED)) {
 			clear_bit(EVENT_FILE_FL_ENABLED_BIT, &file->flags);
@@ -812,8 +813,8 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 
 			WARN_ON_ONCE(ret);
 		}
-		/* If in SOFT_MODE, just set the SOFT_DISABLE_BIT, else clear it */
-		if (file->flags & EVENT_FILE_FL_SOFT_MODE)
+		/* If in soft mode, just set the SOFT_DISABLE_BIT, else clear it */
+		if (soft_mode)
 			set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
 		else
 			clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
@@ -823,7 +824,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		 * When soft_disable is set and enable is set, we want to
 		 * register the tracepoint for the event, but leave the event
 		 * as is. That means, if the event was already enabled, we do
-		 * nothing (but set SOFT_MODE). If the event is disabled, we
+		 * nothing (but set soft_mode). If the event is disabled, we
 		 * set SOFT_DISABLED before enabling the event tracepoint, so
 		 * it still seems to be disabled.
 		 */
@@ -832,7 +833,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		else {
 			if (atomic_inc_return(&file->sm_ref) > 1)
 				break;
-			set_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags);
+			soft_mode = true;
 			/* Enable use of trace_buffered_event */
 			trace_buffered_event_enable();
 		}
@@ -840,7 +841,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
 			bool cmd = false, tgid = false;
 
-			/* Keep the event disabled, when going to SOFT_MODE. */
+			/* Keep the event disabled, when going to soft mode. */
 			if (soft_disable)
 				set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
 
@@ -1792,8 +1793,7 @@ event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 	    !(flags & EVENT_FILE_FL_SOFT_DISABLED))
 		strcpy(buf, "1");
 
-	if (flags & EVENT_FILE_FL_SOFT_DISABLED ||
-	    flags & EVENT_FILE_FL_SOFT_MODE)
+	if (atomic_read(&file->sm_ref) != 0)
 		strcat(buf, "*");
 
 	strcat(buf, "\n");
@@ -3584,7 +3584,7 @@ static int probe_remove_event_call(struct trace_event_call *call)
 			continue;
 		/*
 		 * We can't rely on ftrace_event_enable_disable(enable => 0)
-		 * we are going to do, EVENT_FILE_FL_SOFT_MODE can suppress
+		 * we are going to do, soft mode can suppress
 		 * TRACE_REG_UNREGISTER.
 		 */
 		if (file->flags & EVENT_FILE_FL_ENABLED)
@@ -3997,7 +3997,7 @@ static int free_probe_data(void *data)
 
 	edata->ref--;
 	if (!edata->ref) {
-		/* Remove the SOFT_MODE flag */
+		/* Remove soft mode */
 		__ftrace_event_enable_disable(edata->file, 0, 1);
 		trace_event_put_ref(edata->file->event_call);
 		kfree(edata);