Hi everyone, I'm a really new contributor and I sent off this RFC to LKML <https://lore.kernel.org/lkml/20250723140129.276874-1-rakaguna...@gmail.com/T/#m1372eb992552491ac37f46f27e5ad09d9efa35ad>, when I probably should have floated the idea here first. In any case, I've pasted my RFC patch below and I would really like any feedback / suggestions on the idea.
Thanks, Raka ---------- Forwarded message --------- From: Raka Gunarto <rakaguna...@gmail.com> Date: Wed, Jul 23, 2025 at 3:01 PM Subject: [RFC PATCH 0/1] compiler_types.h: introduce ASSUME_NONNULL macro for static analysis To: <linux-ker...@vger.kernel.org> Cc: Raka Gunarto <rakaguna...@gmail.com> This proposed patch introduces a new macro ASSUME_NONNULL to suppress false positives of null pointer dereference warnings during static analysis. The patch only includes the macro definition for Clang so far, as I could not silence GCC's static analyzer false positives without ensuring that it wouldn't affect the emitted code. I tested this patch and use of the macro successfully eliminates false positives when used properly and does not affect final code generation. I am new to contributing to the kernel, so I apologise in advance for any mistakes. I welcome all feedback or suggestions for improvement. Rationale: - Use of this optional macro can silence false positives which may reduce patches that fix false positives (such as AI generated patches). - Clear documentation of a non null assumption for other developers - Signal to reviewers to subject patches that use this macro to additional scrutiny, and require justification on why there isn't a null check in the code instead. Motivation: While running Clang's static analyzer on the Linux kernel, I encountered hundreds of false positives related to null pointer dereferences. One such example is in mm/slub.c, where the static analyzer incorrectly reports a potential null pointer dereference on line 3169. n is non-null at that point, but it is non obvious to the static analyzer (and to humans) that get_node() will always return a non-null pointer. Since it is in a performance crtical context, adding a null check would be undesirable (I think). A macro like this can be used to signal the pointer is invariably non-null, without adding a runtime check. Raka Gunarto (1): compiler_types.h: introduce ASSUME_NONNULL macro for static analysis include/linux/compiler-clang.h | 10 ++++++++++ include/linux/compiler_types.h | 5 +++++ 2 files changed, 15 insertions(+) -- 2.43.0 _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
