[for-linus][PATCH 0/3] tracing: Fixes for v7.1

[for-linus][PATCH 0/3] tracing: Fixes for v7.1

[Steven Rostedt]

tracing fixes for v7.1:

- Fix inverted check of registering the stats for branch tracing

  When calling register_stat_tracer() which returns zero on success and
  negative on error, the callers were checking the return of zero as an
  error and printing a warning message. Because this was just a normal
  printk() message and not a WARN(), it wasn't caught in any testing.

  Fix the check to print the warning message when an error actually happens.

- Fix a typo in a comment in tracepoint.h

- Limit the size of event probes to 3K in size

  It is possible to create a dynamic event probe via the tracefs system that
  is greater than the max size of an event that the ring buffer can hold.
  This basically causes the event to become useless. Limit the size of an
  event probe to be 3K as that should be large enough to handle any dynamic
  events being created, and fits within the PAGE_SIZE sub-buffers of the
  ring buffer.

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

Head SHA1: b2aa3b4d64e460ac606f386c24e7d8a873ce6f1a


Breno Leitao (1):
      tracing: branch: Fix inverted check on stat tracer registration

Sheng Che Peng (1):
      tracepoint: Fix typo in tracepoint.h comment

Steven Rostedt (1):
      tracing/probes: Limit size of event probe to 3K

----
 include/linux/tracepoint.h  | 2 +-
 kernel/trace/trace_branch.c | 8 ++++----
 kernel/trace/trace_probe.c  | 6 ++++++
 kernel/trace/trace_probe.h  | 4 +++-
 4 files changed, 14 insertions(+), 6 deletions(-)

[for-linus][PATCH 1/3] tracing: branch: Fix inverted check on stat tracer registration

[Steven Rostedt]

From: Breno Leitao <leitao@debian.org>

init_annotated_branch_stats() and all_annotated_branch_stats() check the
return value of register_stat_tracer() with "if (!ret)", but
register_stat_tracer() returns 0 on success and a negative errno on
failure. The inverted check causes the warning to be printed on every
successful registration, e.g.:

  Warning: could not register annotated branches stats

while leaving real failures silent. The initcall also returned a
hard-coded 1 instead of the actual error.

Invert the check and propagate ret so that the warning fires on real
errors and the initcall reports the correct status.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://patch.msgid.link/20260420-tracing-v1-1-d8f4cd0d6af1@debian.org
Fixes: 002bb86d8d42 ("tracing/ftrace: separate events tracing and stats tracing engine")
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_branch.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 6809b370e991..d1564db95a8f 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -373,10 +373,10 @@ __init static int init_annotated_branch_stats(void)
 	int ret;
 
 	ret = register_stat_tracer(&annotated_branch_stats);
-	if (!ret) {
+	if (ret) {
 		printk(KERN_WARNING "Warning: could not register "
 				    "annotated branches stats\n");
-		return 1;
+		return ret;
 	}
 	return 0;
 }
@@ -438,10 +438,10 @@ __init static int all_annotated_branch_stats(void)
 	int ret;
 
 	ret = register_stat_tracer(&all_branch_stats);
-	if (!ret) {
+	if (ret) {
 		printk(KERN_WARNING "Warning: could not register "
 				    "all branches stats\n");
-		return 1;
+		return ret;
 	}
 	return 0;
 }
-- 
2.53.0

[for-linus][PATCH 2/3] tracepoint: Fix typo in tracepoint.h comment

[Steven Rostedt]

From: Sheng Che Peng <synte4028@gmail.com>

Change "my" to "may" in the description of subsystem configurations.

Link: https://patch.msgid.link/20260422021819.1788091-1-synte4028@gmail.com
Signed-off-by: Sheng Che Peng <synte4028@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/tracepoint.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 578e520b6ee6..763eea4d80d8 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -202,7 +202,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 #define TP_CONDITION(args...)	args
 
 /*
- * Individual subsystem my have a separate configuration to
+ * Individual subsystem may have a separate configuration to
  * enable their tracepoints. By default, this file will create
  * the tracepoints if CONFIG_TRACEPOINTS is defined. If a subsystem
  * wants to be able to disable its tracepoints from being created
-- 
2.53.0

[for-linus][PATCH 3/3] tracing/probes: Limit size of event probe to 3K

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

There currently isn't a max limit an event probe can be. One could make an
event greater than PAGE_SIZE, which makes the event useless because if
it's bigger than the max event that can be recorded into the ring buffer,
then it will never be recorded.

A event probe should never need to be greater than 3K, so make that the
max size. As long as the max is less than the max that can be recorded
onto the ring buffer, it should be fine.

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: 93ccae7a22274 ("tracing/kprobes: Support basic types on dynamic events")
Link: https://patch.msgid.link/20260428122302.706610ba@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.c | 6 ++++++
 kernel/trace/trace_probe.h | 4 +++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index e1c73065dae5..e0d3a0da26af 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -1523,6 +1523,12 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
 	parg->offset = *size;
 	*size += parg->type->size * (parg->count ?: 1);
 
+	if (*size > MAX_PROBE_EVENT_SIZE) {
+		ret = -E2BIG;
+		trace_probe_log_err(ctx->offset, EVENT_TOO_BIG);
+		goto fail;
+	}
+
 	if (parg->count) {
 		len = strlen(parg->type->fmttype) + 6;
 		parg->fmt = kmalloc(len, GFP_KERNEL);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 9fc56c937130..262d8707a3df 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -38,6 +38,7 @@
 #define MAX_BTF_ARGS_LEN	128
 #define MAX_DENTRY_ARGS_LEN	256
 #define MAX_STRING_SIZE		PATH_MAX
+#define MAX_PROBE_EVENT_SIZE	3072
 
 /* Reserved field names */
 #define FIELD_STRING_IP		"__probe_ip"
@@ -561,7 +562,8 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	C(BAD_TYPE4STR,		"This type does not fit for string."),\
 	C(NEED_STRING_TYPE,	"$comm and immediate-string only accepts string type"),\
 	C(TOO_MANY_ARGS,	"Too many arguments are specified"),	\
-	C(TOO_MANY_EARGS,	"Too many entry arguments specified"),
+	C(TOO_MANY_EARGS,	"Too many entry arguments specified"),	\
+	C(EVENT_TOO_BIG,	"Event too big (too many fields?)"),
 
 #undef C
 #define C(a, b)		TP_ERR_##a
-- 
2.53.0