Hi Am 06.03.23 um 23:37 schrieb Randy Dunlap: [...]
+ * + * The call to option_iter_init() initializes the iterator instance + * from the option string. The while loop walks over the individual + * options in the sting and returns each in the second argument. The + * returned memory is owned by the iterator instance and callers may + * not modify or free it. The call to option_iter_release() frees all + * resources of the iterator. This process does not modify the original + * option string. If the option string contains an empty option (i.e., + * two commas next to each other), option_iter_next() skips the empty + * option automatically.Is that latter skipping over a ",," automatically something that you have observed as needed?
It's not strictly needed for correctness, but many of those fbdev drivers contain code to do that. Like this one:
https://elixir.bootlin.com/linux/v6.2/source/drivers/video/fbdev/vesafb.c#L217 So doing it in the _incr() helper seems useful
I can imagine a driver or module wanting to know that an empty string was entered (i.e., ",,").
I only looked at fbdev drivers, but none of them cared about empty strings. They all have named options and/or key-value pairs.
+ */ + +/** + * option_iter_init - Initializes an option iterator + * @iter: the iterator to initialize + * @options: the options string + */ +void option_iter_init(struct option_iter *iter, const char *options) +{ + if (options && *options) + iter->optbuf = kstrdup(options, GFP_KERNEL); // can be NULL + else + iter->optbuf = NULL; + iter->next_opt = iter->optbuf; +} +EXPORT_SYMBOL(option_iter_init); + +/** + * option_iter_release - Releases an option iterator's resources + * @iter: the iterator + */ +void option_iter_release(struct option_iter *iter) +{ + kfree(iter->optbuf); + iter->next_opt = NULL; +} +EXPORT_SYMBOL(option_iter_release); + +/** + * option_iter_incr - Return current option and advance to the next + * @iter: the iterator + * + * Returns:* Return: matches kernel-doc notation documentation.+ * The current option string, or NULL if there are no more options. + */ +const char *option_iter_incr(struct option_iter *iter) +{ + char *opt; + + if (!iter->next_opt) { // can be OK if kstrdup failed + if (iter->optbuf) // iter has already been released; logic error + pr_err("Incrementing option iterator without string\n"); + return NULL; + } + + do { + opt = strsep(&iter->next_opt, ","); + if (!opt) + return NULL; + } while (!*opt); // found empty option string, try next + + return opt; +} +EXPORT_SYMBOL(option_iter_incr);Looks useful. Thanks.
Thanks. Best regards Thomas
-- 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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