From: Andy Lutomirski Date: Thu, 16 Apr 2015 19:44:47 +0000 (-0700) Subject: errno.h: Improve ENOSYS's comment X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e15f431fe2d53cd4673510736da7d4fa1090e096;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git errno.h: Improve ENOSYS's comment ENOSYS is the mechanism used by user code to detect whether the running kernel implements a given system call. It should not be returned by anything except an unimplemented system call. Unfortunately, it is rather frequently used in the kernel to indicate that various new functions of existing system calls are not implemented. This should be discouraged. Improve the comment in errno.h to help clarify ENOSYS's purpose. Signed-off-by: Andy Lutomirski Cc: Pavel Machek Cc: Michael Kerrisk Cc: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/errno.h index 1e1ea6e6e7a5..88e0914cf2d9 100644 --- a/include/uapi/asm-generic/errno.h +++ b/include/uapi/asm-generic/errno.h @@ -6,7 +6,16 @@ #define EDEADLK 35 /* Resource deadlock would occur */ #define ENAMETOOLONG 36 /* File name too long */ #define ENOLCK 37 /* No record locks available */ -#define ENOSYS 38 /* Function not implemented */ + +/* + * This error code is special: arch syscall entry code will return + * -ENOSYS if users try to call a syscall that doesn't exist. To keep + * failures of syscalls that really do exist distinguishable from + * failures due to attempts to use a nonexistent syscall, syscall + * implementations should refrain from returning -ENOSYS. + */ +#define ENOSYS 38 /* Invalid system call number */ + #define ENOTEMPTY 39 /* Directory not empty */ #define ELOOP 40 /* Too many symbolic links encountered */ #define EWOULDBLOCK EAGAIN /* Operation would block */