Add a new selftest for testing counter and counter_atomic counters api. This test load test_counters test modules and unloads.
The test module runs tests and prints results in dmesg.
There are a number of atomic_t usages in the kernel where atomic_t api is used strictly for counting and not for managing object lifetime. In some cases, atomic_t might not even be needed.
The purpose of these counters is twofold: 1. clearly differentiate atomic_t counters from atomic_t usages that guard object lifetimes, hence prone to overflow and underflow errors. It allows tools that scan for underflow and overflow on atomic_t usages to detect overflow and underflows to scan just the cases that are prone to errors. 2. provides non-atomic counters for cases where atomic isn't necessary.
Simple atomic and non-atomic counters api provides interfaces for simple atomic and non-atomic counters that just count, and don't guard resource lifetimes. Counters will wrap around to 0 when it overflows and should not be used to guard resource lifetimes, device usage and open counts that control state changes, and pm states.
Using counter_atomic to guard lifetimes could lead to use-after free when it overflows and undefined behavior when used to manage state changes and device usage/open states.
Signed-off-by: Shuah Khan skhan@linuxfoundation.org --- MAINTAINERS | 1 + tools/testing/selftests/lib/Makefile | 1 + tools/testing/selftests/lib/config | 1 + tools/testing/selftests/lib/test_counters.sh | 5 +++++ 4 files changed, 8 insertions(+) create mode 100755 tools/testing/selftests/lib/test_counters.sh
diff --git a/MAINTAINERS b/MAINTAINERS index 1d3abcfa76ab..fc802ef0ee95 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15847,6 +15847,7 @@ L: linux-kernel@vger.kernel.org S: Maintained F: include/linux/counters.h F: lib/test_counters.c +F: tools/testing/selftests/lib/test_counters.sh
SIMPLE FIRMWARE INTERFACE (SFI) S: Obsolete diff --git a/tools/testing/selftests/lib/Makefile b/tools/testing/selftests/lib/Makefile index a105f094676e..e8960d7934e2 100644 --- a/tools/testing/selftests/lib/Makefile +++ b/tools/testing/selftests/lib/Makefile @@ -5,5 +5,6 @@ all:
TEST_PROGS := printf.sh bitmap.sh prime_numbers.sh strscpy.sh +TEST_PROGS += test_counters.sh
include ../lib.mk diff --git a/tools/testing/selftests/lib/config b/tools/testing/selftests/lib/config index b80ee3f6e265..6ed25024d371 100644 --- a/tools/testing/selftests/lib/config +++ b/tools/testing/selftests/lib/config @@ -3,3 +3,4 @@ CONFIG_TEST_BITMAP=m CONFIG_PRIME_NUMBERS=m CONFIG_TEST_STRSCPY=m CONFIG_TEST_BITOPS=m +CONFIG_TEST_COUNTERS=m diff --git a/tools/testing/selftests/lib/test_counters.sh b/tools/testing/selftests/lib/test_counters.sh new file mode 100755 index 000000000000..d1a130190e3f --- /dev/null +++ b/tools/testing/selftests/lib/test_counters.sh @@ -0,0 +1,5 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# Tests the Simple Atomic and Non-atomic Counters interfaces using +# test_counters kernel module +$(dirname $0)/../kselftest/module.sh "test_counters" test_counters