linux-kernel - [GIT PULL v2] tracing: tracing: user

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Date:   Wed, 28 Jun 2023 10:54:25 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        sunliming <sunliming@...inos.cn>,
        Beau Belgrave <beaub@...ux.microsoft.com>
Subject: [GIT PULL v2] tracing: tracing: user_event fix for 6.4


Linus,

tracing: Fix user event write on buffer disabled

The user events write currently returns the size of what was suppose to be
written when tracing is disabled and nothing was written. Instead, behave like
trace_marker and return -EBADF, as that is what is returned if a file is opened
for read only, and a write is performed on it. Writing to the buffer
that is disabled is like trying to write to a file opened for read
only, as the buffer still can be read, but just not written to.

This also includes test cases for this use case.


Please pull the latest trace-v6.4-rc7-v2 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-v6.4-rc7-v2

Tag SHA1: 02efa9f9b19b0d881812bae9b3e28d539b67a863
Head SHA1: e155047e53d25f09d055c08ae9d6c269520e90d8


sunliming (3):
      tracing/user_events: Fix incorrect return value for writing operation when events are disabled
      selftests/user_events: Enable the event before write_fault test in ftrace self-test
      selftests/user_events: Add test cases when event is disabled

----
 kernel/trace/trace_events_user.c                  | 3 ++-
 tools/testing/selftests/user_events/ftrace_test.c | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
---------------------------
diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 8df0550415e7..09f7d9167b8e 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -2096,7 +2096,8 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i)
 
 		if (unlikely(faulted))
 			return -EFAULT;
-	}
+	} else
+		return -EBADF;
 
 	return ret;
 }
diff --git a/tools/testing/selftests/user_events/ftrace_test.c b/tools/testing/selftests/user_events/ftrace_test.c
index eb6904d89f14..5beb0aef1d81 100644
--- a/tools/testing/selftests/user_events/ftrace_test.c
+++ b/tools/testing/selftests/user_events/ftrace_test.c
@@ -324,6 +324,10 @@ TEST_F(user, write_events) {
 	io[0].iov_base = &reg.write_index;
 	io[0].iov_len = sizeof(reg.write_index);
 
+	/* Write should return -EBADF when event is not enabled */
+	ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
+	ASSERT_EQ(EBADF, errno);
+
 	/* Enable event */
 	self->enable_fd = open(enable_file, O_RDWR);
 	ASSERT_NE(-1, write(self->enable_fd, "1", sizeof("1")))
@@ -400,6 +404,10 @@ TEST_F(user, write_fault) {
 	ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
 	ASSERT_EQ(0, reg.write_index);
 
+	/* Enable event */
+	self->enable_fd = open(enable_file, O_RDWR);
+	ASSERT_NE(-1, write(self->enable_fd, "1", sizeof("1")))
+
 	/* Write should work normally */
 	ASSERT_NE(-1, writev(self->data_fd, (const struct iovec *)io, 2));