linux/scripts/mod/modpost.h, branch v5.11

modpost: refactor error handling and clarify error/fatal difference

2020-12-21T04:57:08Z

We have 3 log functions. fatal() is special because it lets modpost bail out immediately. The difference between warn() and error() is the only prefix parts ("WARNING:" vs "ERROR:"). In my understanding, the expected handling of error() is to propagate the return code of the function to the exit code of modpost, as check_exports() etc. already does. This is a good manner in general because we should display as many error messages as possible in a single run of modpost. What is annoying about fatal() is that it kills modpost at the first error. People would need to run Kbuild again and again until they fix all errors. But, unfortunately, people tend to do: "This case should not be allowed. Let's replace warn() with fatal()." One of the reasons is probably it is tedious to manually hoist the error code to the main() function. This commit refactors error() so any single call for it automatically makes modpost return the error code. I also added comments in modpost.h for warn(), error(), and fatal(). Please use fatal() only when you have a strong reason to do so. For example: - Memory shortage (i.e. malloc() etc. has failed) - The ELF file is broken, and there is no point to continue parsing - Something really odd has happened For general coding errors, please use error(). Signed-off-by: Masahiro Yamada Tested-by: Quentin Perret

modpost: rename merror() to error()

2020-12-21T04:57:08Z

The log function names, warn(), merror(), fatal() are inconsistent. Commit 2a11665945d5 ("kbuild: distinguish between errors and warnings in modpost") intentionally chose merror() to avoid the conflict with the library function error(). See man page of error(3). But, we are already causing the conflict with warn() because it is also a library function. See man page of warn(3). err() would be a problem for the same reason. The common technique to work around name conflicts is to use macros. For example: /* in a header */ #define error(fmt, ...) __error(fmt, ##__VA_ARGS__) #define warn(fmt, ...) __warn(fmt, ##__VA_ARGS__) /* function definition */ void __error(const char *fmt, ...) { } void __warn(const char *fmt, ...) { } In this way, we can implement our own warn() and error(), still we can include and with no problem. And, commit 93c95e526a4e ("modpost: rework and consolidate logging interface") already did that. Since the log functions are all macros, we can use error() without causing "conflicting types" errors. Signed-off-by: Masahiro Yamada

modpost: change elf_info->size to size_t

2020-06-06T14:39:20Z

Align with the mmap / munmap APIs. Signed-off-by: Masahiro Yamada

modpost: strip .o from modname before calling new_module()

2020-06-06T14:39:20Z

new_module() conditionally strips the .o because the modname has .o suffix when it is called from read_symbols(), but no .o when it is called from read_dump(). It is clearer to strip .o in read_symbols(). I also used flexible-array for mod->name. Signed-off-by: Masahiro Yamada

modpost: remove mod->skip struct member

2020-06-06T14:39:20Z

The meaning of 'skip' is obscure since it does not explain "what to skip". mod->skip is set when it is vmlinux or the module info came from a dump file. So, mod->skip is equivalent to (mod->is_vmlinux || mod->from_dump). For the check in write_namespace_deps_files(), mod->is_vmlinux is unneeded because the -d option is not passed in the first pass of modpost. Signed-off-by: Masahiro Yamada

modpost: add mod->is_vmlinux struct member

2020-06-06T14:39:19Z

is_vmlinux() is called in several places to check whether the current module is vmlinux or not. It is faster and clearer to check mod->is_vmlinux flag. Signed-off-by: Masahiro Yamada

modpost: remove mod->is_dot_o struct member

2020-06-06T14:38:13Z

Previously, there were two cases where mod->is_dot_o is unset: [1] the executable 'vmlinux' in the second pass of modpost [2] modules loaded by read_dump() I think [1] was intended usage to distinguish 'vmlinux.o' and 'vmlinux'. Now that modpost does not parse the executable 'vmlinux', this case does not happen. [2] is obscure, maybe a bug. Module.symver stores module paths without extension. So, none of modules loaded by read_dump() has the .o suffix, and new_module() unsets ->is_dot_o. Anyway, it is not a big deal because handle_symbol() is not called for the case. To sum up, all the parsed ELF files are .o files. mod->is_dot_o is unneeded. Signed-off-by: Masahiro Yamada

modpost: remove get_next_text() and make {grab,release_}file static

2020-06-06T14:38:13Z

get_next_line() is no longer used. Remove. grab_file() and release_file() are only used in modpost.c. Make them static. Signed-off-by: Masahiro Yamada

modpost: add read_text_file() and get_line() helpers

2020-06-06T14:38:12Z

modpost uses grab_file() to open a file, but it is not suitable for a text file because the mmap'ed file is not terminated by null byte. Actually, I see some issues for the use of grab_file(). The new helper, read_text_file() loads the whole file content into a malloc'ed buffer, and appends a null byte. Then, get_line() reads each line. To handle text files, I intend to replace as follows: grab_file() -> read_text_file() get_new_line() -> get_line() Signed-off-by: Masahiro Yamada

modpost: drop RCS/CVS $Revision handling in MODULE_VERSION()

2020-06-06T14:38:12Z

As far as I understood, this code gets rid of '$Revision$' or '$Revision:' of CVS, RCS or whatever in MODULE_VERSION() tags. Remove the primeval code. Signed-off-by: Masahiro Yamada