[PW_SID:1095409] kunit: Add support for suppressing warning backtraces by linux-riscv-bot · Pull Request #1947 · linux-riscv/linux

linux-riscv-bot · 2026-05-15T14:52:59Z

PR for series 1095409 applied to workflow__riscv__fixes

Name: kunit: Add support for suppressing warning backtraces
URL: https://patchwork.kernel.org/project/linux-riscv/list/?series=1095409
Version: 13

Some unit tests intentionally trigger warning backtraces by passing bad parameters to kernel API functions. Such unit tests typically check the return value from such calls, not the existence of the warning backtrace. Such intentionally generated warning backtraces are neither desirable nor useful for a number of reasons: - They can result in overlooked real problems. - A warning that suddenly starts to show up in unit tests needs to be investigated and has to be marked to be ignored, for example by adjusting filter scripts. Such filters are ad hoc because there is no real standard format for warnings. On top of that, such filter scripts would require constant maintenance. Solve the problem by providing a means to suppress warning backtraces originating from the current kthread while executing test code. Since each KUnit test runs in its own kthread, this effectively scopes suppression to the test that enabled it. Limit changes to generic code to the absolute minimum. Implementation details: Suppression is integrated into the existing KUnit hooks infrastructure in test-bug.h, reusing the kunit_running static branch for zero overhead when no tests are running. Suppression is checked at three points in the warning path: - In warn_slowpath_fmt(), the check runs before any output, fully suppressing both message and backtrace. This covers architectures without __WARN_FLAGS. - In __warn_printk(), the check suppresses the warning message text. This covers architectures that define __WARN_FLAGS but not their own __WARN_printf (arm64, loongarch, parisc, powerpc, riscv, sh), where the message is printed before the trap enters __report_bug(). - In __report_bug(), the check runs before __warn() is called, suppressing the backtrace and stack dump. To avoid double-counting on architectures where both __warn_printk() and __report_bug() run for the same warning, kunit_is_suppressed_warning() takes a bool parameter: true to increment the suppression counter (used in warn_slowpath_fmt and __report_bug), false to check only (used in __warn_printk). The suppression state is dynamically allocated via kunit_kzalloc() and tied to the KUnit test lifecycle via kunit_add_action(), ensuring automatic cleanup at test exit. On cleanup, the node is removed with list_del_rcu() followed by synchronize_rcu() to wait for any concurrent RCU readers to finish. Because kunit_end_suppress_warning() (and the __cleanup wrapper) always runs from process context, synchronize_rcu() is safe. The handle memory remains valid until the test exits, so the suppression count can be read after the scope closes. Writer-side access to the global suppression list is serialized with a spinlock; readers use RCU. To avoid false suppression of warnings fired from hardware interrupt handlers (where current still points to the test task), the check exits early when not in task context. Two API forms are provided: - kunit_warning_suppress(test) { ... }: scoped, uses __cleanup for automatic teardown on scope exit, kunit_add_action() as safety net for abnormal exits (e.g. kthread_exit from failed assertions). Suppression handle is only accessible inside the block. - kunit_start/end_suppress_warning(test): direct functions returning an explicit handle, for retaining the handle within the test, or for cross-function usage. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Alessandro Carminati <acarmina@redhat.com> Reviewed-by: Kees Cook <kees@kernel.org> Reviewed-by: David Gow <david@davidgow.net> Signed-off-by: Albert Esteve <aesteve@redhat.com> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>

Add unit tests to verify that warning backtrace suppression works. Tests cover both API forms: - Scoped: kunit_warning_suppress() with in-block count verification and post-block inactivity check. - Direct functions: kunit_start/end_suppress_warning() with sequential independent suppression blocks and per-block counts. Furthermore, tests verify incremental warning counting, that kunit_has_active_suppress_warning() transitions correctly around suppression boundaries, and that suppression active in the test kthread does not leak to a separate kthread. If backtrace suppression does _not_ work, the unit tests will likely trigger unsuppressed backtraces, which should actually help to get the affected architectures / platforms fixed. Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Acked-by: Dan Carpenter <dan.carpenter@linaro.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Alessandro Carminati <acarmina@redhat.com> Reviewed-by: David Gow <david@davidgow.net> Signed-off-by: Albert Esteve <aesteve@redhat.com> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>

The drm_test_rect_calc_hscale and drm_test_rect_calc_vscale unit tests intentionally trigger warning backtraces by providing invalid parameters the tested functions. Suppress the backtraces to avoid clogging the kernel log and distracting from real problems. The suppression API also exposes a warning counter, which is used to assert that the expected warning was actually triggered. On CONFIG_BUG=n, WARN_ON() is a no-op and the counter stays zero; the expected count is adjusted accordingly, preserving the return value check on all configurations. Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Acked-by: Dan Carpenter <dan.carpenter@linaro.org> Acked-by: Maíra Canal <mcanal@igalia.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: David Airlie <airlied@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Alessandro Carminati <acarmina@redhat.com> Acked-by: David Gow <david@davidgow.net> Signed-off-by: Albert Esteve <aesteve@redhat.com> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>

Document API functions for suppressing warning backtraces. Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Acked-by: Dan Carpenter <dan.carpenter@linaro.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Alessandro Carminati <acarmina@redhat.com> Reviewed-by: David Gow <david@davidgow.net> Signed-off-by: Albert Esteve <aesteve@redhat.com> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>

linux-riscv-bot · 2026-05-15T14:59:02Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
build-rv32-defconfig
Desc: Builds riscv32 defconfig
Duration: 139.47 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:18:29Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
build-rv64-clang-allmodconfig
Desc: Builds riscv64 allmodconfig with Clang, and checks for errors and added warnings
Duration: 1165.45 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:47:06Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
build-rv64-gcc-allmodconfig
Desc: Builds riscv64 allmodconfig with GCC, and checks for errors and added warnings
Duration: 1715.06 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:47:34Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
build-rv64-nommu-k210-defconfig
Desc: Builds riscv64 defconfig with NOMMU for K210
Duration: 26.14 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:48:03Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
build-rv64-nommu-k210-virt
Desc: Builds riscv64 defconfig with NOMMU for the virt platform
Duration: 27.19 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:48:08Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
checkpatch
Desc: Runs checkpatch.pl on the patch
Duration: 3.55 seconds
Result: WARNING
Output:

WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
#335: 
new file mode 100644

total: 0 errors, 1 warnings, 0 checks, 358 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

Commit 2da4838badd1 ("bug/kunit: Core support for suppressing warning backtraces") has style problems, please review.

NOTE: Ignored message types: ALLOC_SIZEOF_STRUCT CAMELCASE COMMIT_LOG_LONG_LINE GIT_COMMIT_ID MACRO_ARG_REUSE NO_AUTHOR_SIGN_OFF

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.
total: 0 errors, 1 warnings, 0 checks, 358 lines checked
WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?

linux-riscv-bot · 2026-05-15T15:49:37Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
dtb-warn-rv64
Desc: Checks for Device Tree warnings/errors
Duration: 87.53 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:49:39Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
header-inline
Desc: Detects static functions without inline keyword in header files
Duration: 0.25 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:49:42Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
kdoc
Desc: Detects for kdoc errors
Duration: 1.18 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:49:43Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
module-param
Desc: Detect module_param changes
Duration: 0.28 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:49:46Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
verify-fixes
Desc: Verifies that the Fixes: tags exist
Duration: 0.23 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:49:48Z

Patch 1: "[v13,1/4] bug/kunit: Core support for suppressing warning backtraces"
verify-signedoff
Desc: Verifies that Signed-off-by: tags are correct
Duration: 0.31 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T15:52:24Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
build-rv32-defconfig
Desc: Builds riscv32 defconfig
Duration: 140.48 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:09:49Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
build-rv64-clang-allmodconfig
Desc: Builds riscv64 allmodconfig with Clang, and checks for errors and added warnings
Duration: 1042.58 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:33:30Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
build-rv64-gcc-allmodconfig
Desc: Builds riscv64 allmodconfig with GCC, and checks for errors and added warnings
Duration: 1420.21 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:33:58Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
build-rv64-nommu-k210-defconfig
Desc: Builds riscv64 defconfig with NOMMU for K210
Duration: 26.02 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:34:27Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
build-rv64-nommu-k210-virt
Desc: Builds riscv64 defconfig with NOMMU for the virt platform
Duration: 27.27 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:34:31Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
checkpatch
Desc: Runs checkpatch.pl on the patch
Duration: 2.37 seconds
Result: WARNING
Output:

WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
#50: 
new file mode 100644

CHECK: Please use a blank line after function/struct/union/enum declarations
#243: FILE: lib/kunit/backtrace-suppression-test.c:189:
+};
+kunit_test_suites(&backtrace_suppression_test_suite);

total: 0 errors, 1 warnings, 1 checks, 199 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

Commit a8e905db8eb2 ("kunit: Add backtrace suppression self-tests") has style problems, please review.

NOTE: Ignored message types: ALLOC_SIZEOF_STRUCT CAMELCASE COMMIT_LOG_LONG_LINE GIT_COMMIT_ID MACRO_ARG_REUSE NO_AUTHOR_SIGN_OFF

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.
total: 0 errors, 1 warnings, 1 checks, 199 lines checked
CHECK: Please use a blank line after function/struct/union/enum declarations
WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?

linux-riscv-bot · 2026-05-15T16:35:58Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
dtb-warn-rv64
Desc: Checks for Device Tree warnings/errors
Duration: 86.20 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:36:00Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
header-inline
Desc: Detects static functions without inline keyword in header files
Duration: 0.24 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:36:03Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
kdoc
Desc: Detects for kdoc errors
Duration: 0.90 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:36:04Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
module-param
Desc: Detect module_param changes
Duration: 0.26 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:36:06Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
verify-fixes
Desc: Verifies that the Fixes: tags exist
Duration: 0.23 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:36:08Z

Patch 2: "[v13,2/4] kunit: Add backtrace suppression self-tests"
verify-signedoff
Desc: Verifies that Signed-off-by: tags are correct
Duration: 0.31 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:38:44Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
build-rv32-defconfig
Desc: Builds riscv32 defconfig
Duration: 141.11 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T16:56:12Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
build-rv64-clang-allmodconfig
Desc: Builds riscv64 allmodconfig with Clang, and checks for errors and added warnings
Duration: 1046.30 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:19:55Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
build-rv64-gcc-allmodconfig
Desc: Builds riscv64 allmodconfig with GCC, and checks for errors and added warnings
Duration: 1421.97 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:20:23Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
build-rv64-nommu-k210-defconfig
Desc: Builds riscv64 defconfig with NOMMU for K210
Duration: 25.93 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:20:52Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
build-rv64-nommu-k210-virt
Desc: Builds riscv64 defconfig with NOMMU for the virt platform
Duration: 27.16 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:20:54Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
checkpatch
Desc: Runs checkpatch.pl on the patch
Duration: 0.80 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:22:22Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
dtb-warn-rv64
Desc: Checks for Device Tree warnings/errors
Duration: 85.78 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:22:23Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
header-inline
Desc: Detects static functions without inline keyword in header files
Duration: 0.25 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:22:26Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
kdoc
Desc: Detects for kdoc errors
Duration: 0.85 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:22:28Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
module-param
Desc: Detect module_param changes
Duration: 0.26 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:22:30Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
verify-fixes
Desc: Verifies that the Fixes: tags exist
Duration: 0.24 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:22:32Z

Patch 3: "[v13,3/4] drm: Suppress intentional warning backtraces in scaling unit tests"
verify-signedoff
Desc: Verifies that Signed-off-by: tags are correct
Duration: 0.29 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:25:06Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
build-rv32-defconfig
Desc: Builds riscv32 defconfig
Duration: 140.01 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T17:42:03Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
build-rv64-clang-allmodconfig
Desc: Builds riscv64 allmodconfig with Clang, and checks for errors and added warnings
Duration: 1015.39 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:05:07Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
build-rv64-gcc-allmodconfig
Desc: Builds riscv64 allmodconfig with GCC, and checks for errors and added warnings
Duration: 1382.01 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:05:35Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
build-rv64-nommu-k210-defconfig
Desc: Builds riscv64 defconfig with NOMMU for K210
Duration: 26.09 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:06:04Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
build-rv64-nommu-k210-virt
Desc: Builds riscv64 defconfig with NOMMU for the virt platform
Duration: 27.29 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:06:07Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
checkpatch
Desc: Runs checkpatch.pl on the patch
Duration: 0.72 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:07:34Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
dtb-warn-rv64
Desc: Checks for Device Tree warnings/errors
Duration: 85.66 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:07:36Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
header-inline
Desc: Detects static functions without inline keyword in header files
Duration: 0.25 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:07:39Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
kdoc
Desc: Detects for kdoc errors
Duration: 0.86 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:07:41Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
module-param
Desc: Detect module_param changes
Duration: 0.26 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:07:43Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
verify-fixes
Desc: Verifies that the Fixes: tags exist
Duration: 0.24 seconds
Result: PASS

linux-riscv-bot · 2026-05-15T18:07:45Z

Patch 4: "[v13,4/4] kunit: Add documentation for warning backtrace suppression API"
verify-signedoff
Desc: Verifies that Signed-off-by: tags are correct
Duration: 0.30 seconds
Result: PASS

alessandrocarminati and others added 4 commits May 15, 2026 14:52

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