Messages in this thread Patch in this message | | | From | Randy Dunlap <> | Subject | [RFC PATCH 1/2] init.h: improve __setup and early_param documentation | Date | Sun, 20 Feb 2022 21:08:52 -0800 |
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Igor noted in [1] that there are quite a few __setup() handling functions that return incorrect values. Doing this can be harmless, but it can also cause strings to be added to init's argument or environment list, polluting them.
Since __setup() handling and return values are not documented, first add documentation for that. Also add more documentation for early_param() handling and return values.
For __setup() functions, returning 0 (not handled) has questionable value if it is just a malformed option value, as in rodata=junk since returning 0 would just cause "rodata=junk" to be added to init's environment unnecessarily: Run /sbin/init as init process with arguments: /sbin/init with environment: HOME=/ TERM=linux splash=native rodata=junk
Also, there are no recommendations on whether to print a warning when an unknown parameter value is seen. I am not addressing that here.
[1] lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- include/linux/init.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- linux-next-20220217.orig/include/linux/init.h +++ linux-next-20220217/include/linux/init.h @@ -320,12 +320,19 @@ struct obs_kernel_param { __aligned(__alignof__(struct obs_kernel_param)) \ = { __setup_str_##unique_id, fn, early } +/* + * NOTE: __setup functions return values: + * @fn returns 1 (or non-zero) if the option argument is "handled" + * and returns 0 if the option argument is "not handled". + */ #define __setup(str, fn) \ __setup_param(str, fn, fn, 0) /* - * NOTE: fn is as per module_param, not __setup! - * Emits warning if fn returns non-zero. + * NOTE: @fn is as per module_param, not __setup! + * I.e., @fn returns 0 for no error or non-zero for error + * (possibly @fn returns a -errno value, but it does not matter). + * Emits warning if @fn returns non-zero. */ #define early_param(str, fn) \ __setup_param(str, fn, fn, 1)
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