Hi Am 10.03.23 um 09:21 schrieb Geert Uytterhoeven:
Hi Thomas, On Thu, Mar 9, 2023 at 5:02 PM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:Add struct option_iter and helpers that walk over individual options of an option string. Add documentation. Kernel parameters often have the format of param=opt1,opt2:val,opt3 where the option string contains a number of comma-separated options. Drivers usually use strsep() in a loop to extract individual options from the string. Each call to strsep() modifies the given string, so callers have to duplicate kernel parameters that are to be parsed multiple times. The new struct option_iter and its helpers wrap this code behind a clean interface. Drivers can iterate over the options without having to know the details of the option-string format. The iterator handles string memory internally without modifying the original options. v2: * improve documentation (Randy) * implement option_iter_next() as function * allow modification of the returned options Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>Thanks for your patch! I> ---Documentation/core-api/kernel-api.rst | 9 +++ include/linux/cmdline.h | 36 +++++++++ lib/Makefile | 2 +- lib/cmdline_iter.c | 109 ++++++++++++++++++++++++++ 4 files changed, 155 insertions(+), 1 deletion(-) create mode 100644 include/linux/cmdline.h create mode 100644 lib/cmdline_iter.cJust wondering, is there any code that can be shared with/reused from the existing lib/cmdline.c?
AFAIU, cmdline.o is linked into early-boot code, which prevents it from using dynamic memory allocation, such as kstrdup() and kfree(). The linker warns about this:
LD arch/x86/boot/compressed/vmlinux ld: arch/x86/boot/compressed/kaslr.o: in function `get_option': kaslr.c:(.text+0x532): undefined reference to `kstrdup' ld: arch/x86/boot/compressed/vmlinux: hidden symbol `kstrdup' isn't defined ld: final link failed: bad value So the iterator is in a separate source file.The code in cmdline.c mostly deals with parsing individual values or key-value pairs. Nothing moves over the complete string and returns options one by one. There's not much to share AFAICT.
Best regards Thomas
Gr{oetje,eeting}s,
Geert
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
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