Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 10 Mar 2023 13:38:24 +0100 | Subject | Re: [PATCH v2 001/101] lib: Add option iterator | From | Thomas Zimmermann <> |
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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@suse.de> 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@suse.de> > > 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.c > > Just 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 [unhandled content-type:application/pgp-signature] | ![\](/images/icornerr.gif) |