Rob Norris 96f382d113 spl/thread: explicitly define thread_func_t as noreturn ... All of our thread entry functions have this signature: void (*)(void*) __attribute__((noreturn)) The low-level `__thread_create()` function accepts a `thread_func_t` as the entry point, which is defined more simply as: void (*)(void *) And then the `thread_create()` and `thread_create_named()` macros cast the passed-in function point down to `thread_func_t`, that is, casting away the `noreturn` attribute. Clang considers casting between these two types to be invalid because both the caller and the callee may have elided parts of the stack frame save and restore, knowing that they won't be needed. Recent Linux appears to be setting `-Wcast-function-type-strict`, which causes this invalid cast to emit a warning, which with `-Werror` is converted to an error, breaking the build. This commit fixes this in the simplest possible way: adding `noreturn` to the `thread_func_t` attribute. Since all our thread entry functions already have this attribute, it's arguably a just a consistency fix anyway. I considered removing the casts in the macros, which silences the warnings, but it turns out that Clang has a bug that won't emit this error for implicit conversions, only explicit casts. So leaving them there seems like a reasonable belt-and-suspenders approach. Also, frankly, this whole mechanism seems a little undercooked inside LLVM, so I'm content go with my intuition about the smallest, least invaisve change. **NOTE**: `__thread_create` is exported by `spl.ko` and has a `thread_func_t` arg, so this is an ABI break. Whether that matters in practice, I have no idea. Further reading: - 1aad641c79 - https://github.com/llvm/llvm-project/issues/7325 - https://github.com/llvm/llvm-project/issues/41465 Sponsored-by: https://despairlabs.com/sponsor/ Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Rob Norris <robn@despairlabs.com> Closes #16672 Closes #16673		2024-10-21 11:38:30 -07:00
..
freebsd	freebsd: Use compiler.h from FreeBSD's base's linuxkpi	2024-10-16 13:00:40 -04:00
linux	spl/thread: explicitly define thread_func_t as noreturn	2024-10-21 11:38:30 -07:00