parse_thread_config_string(9)

💅 parse_thread_config_string(9) — the kernel API manual, bestie edition ✨

Okay so this is parse_thread_config_string(9), straight out of the Kernel API Manual, and it's honestly giving "small function, big responsibilities" energy. Buckle up 🎀

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🌸 NAME 🌸

parse_thread_config_string — she takes the configuration string you hand her and updates all the counts and other parameters for the various types of threads you're about to create. No cap, that's the whole job. 💖

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✨ SYNOPSIS ✨

int parse_thread_config_string (const char *string , struct
thread_count_config *config );

That return type is int, she's const char * on the way in and a struct thread_count_config * on the way through. Slay. 🫶

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🦋 ARGUMENTS 🦋

• string — the thread parameter configuration string. That's the input, the raw text, the little stringy friend you're feeding in. 🍓
• config — the thread configuration data she's gonna update. This is the struct that gets its glow-up. ✨

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👑 DESCRIPTION 👑

So here's the vibe: the configuration string should contain one or more comma-separated specs, each of them shaped like this:

"typename=number"

And the supported type names? Bestie, let me list them, because the list is iconic and you need all of them:

• cpu
• ack
• bio
• bioRotationInterval
• logical
• physical
• hash

Periodt. Those are the only names she knows. 💅

Heads up: if an error happens while parsing a single key/value pair, the function deems it serious enough to stop further parsing. Like, she's not gonna push through and pretend it's fine. One bad pair and she's out. 😭

And now the part that's genuinely important, so listen up:

This function can't set the "reason" value that the caller wants to pass back. Why? Because we'd want to format that reason to say which field was invalid, and we can't allocate the "reason" strings dynamically. So instead: if an error occurs, she'll log the details and pass back an error. That's the compromise, that's the deal, that's the design. 🙈

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🔥 RETURN 🔥

One of these three, bestie:

• VDO_SUCCESS 🎉
• -EINVAL
• -ENOMEM

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🌈 SEE ALSO 🌈

Okay this list is long and I'm obsessed with it. Everything below is in the kernel file ./drivers/md/dm-vdo/dm-vdo-target.c, and yes, we're listing every single one because we don't skip entries in this house 💜:

• free_device_config(9)
• get_version_number(9)
• parse_bool(9)
• parse_memory(9)
• parse_slab_size(9)
• process_one_thread_config_spec(9)
• parse_one_thread_config_spec(9)
• process_one_key_value_pair(9)
• parse_one_key_value_pair(9)
• parse_key_value_pairs(9)
• parse_optional_arguments(9)
• handle_parse_error(9)
• parse_device_config(9)
• get_thread_id_for_phase(9)
• advance_phase(9)
• finish_operation_callback(9)
• decode_from_super_block(9)
• decode_vdo(9)
• pre_load_callback(9)
• get_bit_array_size(9)
• grow_bit_array(9)
• allocate_instance(9)
• check_may_grow_physical(9)
• grow_layout(9)
• validate_new_device_config(9)
• write_super_block_for_suspend(9)
• suspend_callback(9)
• was_new(9)
• requires_repair(9)
• get_load_type(9)
• load_callback(9)
• handle_load_error(9)
• write_super_block_for_resume(9)
• resume_callback(9)
• grow_logical_callback(9)
• handle_logical_growth_error(9)
• perform_grow_logical(9)
• copy_partition(9)
• grow_physical_callback(9)
• handle_physical_growth_error(9)
• perform_grow_physical(9)
• apply_new_vdo_configuration(9)

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And that's the page, bestie! 🧚 This lil masterpiece lives in ./drivers/md/dm-vdo, dated October 2026, and it goes out to absolutely everyone in the group chat. Mwah. 💖✨💅