[PATCH v2 0/9] seq_buf: Add seq_buf_strlen()

From: Kees Cook

Date: Fri Sep 18 2026 - 20:27:34 EST


Hi,

While working on seq_buf conversions, we found there was a need for
seq_buf_strlen() (since calling strlen(seq_buf_str()) would be a waste of
time: seq_buf already knows the length), and seq_buf_init_append() (to
start a seq_buf from an existing string buffer). And while implementing
that, we found a bunch of other related things that needed fixing. This
is that series, with tests for each fix.

v1: https://lore.kernel.org/all/20260917002312.i.923-kees@xxxxxxxxxx/
v2:
- seq_buf_do_printk() simplification and more tests
- add seq_buf_init_append() and tests[1]
- finish documenting seq_buf[1] and link it to kernel api docs
- test improvements throughout

-Kees

[1] https://lore.kernel.org/all/20260917011359.1585961-1-morbo@xxxxxxxxxx/


Bill Wendling (1):
seq_buf: Add seq_buf_init_append()

Kees Cook (8):
seq_buf: Do not print an empty line from an overflowed
seq_buf_do_printk()
seq_buf: Do not pop from an overflowed seq_buf
seq_buf: Copy what fits when seq_buf_puts() and seq_buf_putmem()
overflow
seq_buf: Clear what a writer did not claim when a seq_buf overflows
seq_buf: Add seq_buf_strlen()
powerpc/papr_scm: Return the string length from the sysfs show
functions
nvdimm: ndtest: Return the string length from flags_show()
docs: core-api: Document the seq_buf API

Documentation/core-api/kernel-api.rst | 9 +
include/linux/seq_buf.h | 103 ++++-
include/linux/trace_seq.h | 5 +-
arch/powerpc/platforms/pseries/papr_scm.c | 4 +-
lib/seq_buf.c | 35 +-
lib/tests/seq_buf_kunit.c | 471 +++++++++++++++++++++-
tools/testing/nvdimm/test/ndtest.c | 2 +-
7 files changed, 607 insertions(+), 22 deletions(-)

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2.34.1