[PATCH v2] seq_buf: export seq_buf_putmem_hex() and add KUnit tests

Shuvam Pandey
2026-04-08T14:45:21Z

The seq_buf KUnit suite does not exercise seq_buf_putmem_hex().

Add one test for the len > 8 chunking path and one overflow test
where a later chunk no longer fits in the buffer.

Export seq_buf_putmem_hex() as well so SEQ_BUF_KUNIT_TEST=m links
cleanly. Without the export, modpost reports seq_buf_putmem_hex as
undefined when seq_buf_kunit is built as a module.

Signed-off-by: Shuvam Pandey <shuvampandey1@gmail.com>
---
v2:
- export seq_buf_putmem_hex() so SEQ_BUF_KUNIT_TEST=m links cleanly
- validate with a fresh arm64 build using CONFIG_KUNIT=y and CONFIG_SEQ_BUF_KUNIT_TEST=m

lib/seq_buf.c | 1 +
lib/tests/seq_buf_kunit.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)

diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index f3f3436d60a9403eae5b1ef9b091b027881f14fb..b59488fa8135cdb0340fbeb43d8d74db8ae13146 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -298,6 +298,7 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
}
return 0;
}
+EXPORT_SYMBOL_GPL(seq_buf_putmem_hex);

/**
* seq_buf_path - copy a path into the sequence buffer
diff --git a/lib/tests/seq_buf_kunit.c b/lib/tests/seq_buf_kunit.c
index 8a01579a978e655cd09024d0ea9c4c9cd095263f..eb466386bbefb1c81773cdae65a8ac3df91cd8ea 100644
--- a/lib/tests/seq_buf_kunit.c
+++ b/lib/tests/seq_buf_kunit.c
@@ -184,6 +184,38 @@ static void seq_buf_get_buf_commit_test(struct kunit *test)
KUNIT_EXPECT_TRUE(test, seq_buf_has_overflowed(&s));
}

+static void seq_buf_putmem_hex_test(struct kunit *test)
+{
+ DECLARE_SEQ_BUF(s, 24);
+ const u8 data[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+#ifdef __BIG_ENDIAN
+ const char *expected = "0001020304050607 0809 ";
+#else
+ const char *expected = "0706050403020100 0908 ";
+#endif
+
+ KUNIT_EXPECT_EQ(test, seq_buf_putmem_hex(&s, data, sizeof(data)), 0);
+ KUNIT_EXPECT_FALSE(test, seq_buf_has_overflowed(&s));
+ KUNIT_EXPECT_EQ(test, seq_buf_used(&s), strlen(expected));
+ KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), expected);
+}
+
+static void seq_buf_putmem_hex_overflow_test(struct kunit *test)
+{
+ DECLARE_SEQ_BUF(s, 20);
+ const u8 data[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+#ifdef __BIG_ENDIAN
+ const char *expected = "0001020304050607 ";
+#else
+ const char *expected = "0706050403020100 ";
+#endif
+
+ KUNIT_EXPECT_EQ(test, seq_buf_putmem_hex(&s, data, sizeof(data)), -1);
+ KUNIT_EXPECT_TRUE(test, seq_buf_has_overflowed(&s));
+ KUNIT_EXPECT_EQ(test, seq_buf_used(&s), 20);
+ KUNIT_EXPECT_STREQ(test, seq_buf_str(&s), expected);
+}
+
static struct kunit_case seq_buf_test_cases[] = {
KUNIT_CASE(seq_buf_init_test),
KUNIT_CASE(seq_buf_declare_test),
@@ -194,6 +226,8 @@ static struct kunit_case seq_buf_test_cases[] = {
KUNIT_CASE(seq_buf_printf_test),
KUNIT_CASE(seq_buf_printf_overflow_test),
KUNIT_CASE(seq_buf_get_buf_commit_test),
+ KUNIT_CASE(seq_buf_putmem_hex_test),
+ KUNIT_CASE(seq_buf_putmem_hex_overflow_test),
{}
};