prb_reserve(9)

💅 prb_reserve — from the Kernel API Manual ✨

okay bestie, settle in, because this is the function every printk writer girlie needs in her life: prb_reserve 🎀

✨ NAME ✨

prb_reserve — reserve space in the ringbuffer. that's it, that's the vibe 💖

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🌸 SYNOPSIS 🌸

bool prb_reserve (struct prb_reserved_entry *e , struct
       printk_ringbuffer *rb , struct printk_record *r );

🦋 ARGUMENTS 🦋

• e — the entry structure you're gonna set up. it's giving "hold my spot" energy 💅
• rb — the ringbuffer you're reserving data in. the main character, lowkey 👑
• r — the record structure you're allocating buffers for 🎀

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💜 DESCRIPTION 💜

so this is the public function, the one that's actually out here for writers to reserve data. no cap 📣

you (the writer) tell it how much text space you want by setting the text_buf_size field of r. and like, to make sure r is properly initialized, you should use prb_rec_init_wr — don't skip that step bestie, it's important 🙈

on success, the fields info and text_buf of r get set by this function, and you should fill them in before committing. also on success, you can use prb_record_text_space on e to query the actual space used for the text data block 🔥

Important: info->text_len needs to be set correctly by the writer so the data can be readable and/or extended. its value is initialized to 0. literally do not forget this one, i'm begging 😭

⭐ CONTEXT ⭐

Any context. and — plot twist — it disables local interrupts on success 💀✨

🫶 RETURN 🫶

true if at least text data could be allocated, otherwise false. slay either way, at least you know 💖

🌈 SEE ALSO 🌈

• Kernel file ./kernel/printk/printk_ringbuffer.c
• printk_ringbuffer overview(9)
• prb_reserve_in_last(9)
• prb_commit(9)
• prb_final_commit(9)
• prb_next_reserve_seq(9)
• prb_read_valid(9)
• prb_read_valid_info(9)
• prb_first_valid_seq(9)
• prb_next_seq(9)
• prb_init(9)
• prb_record_text_space(9)

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and that's the whole page, bestie, you ate that 🍓 this little number lives in ./kernel/printk, dropped October 2026, and it's prb_reserve(9) forever and always 🧚💜 periodt.