llc_pdu_decode_pf_bit(9)

💖 llc_pdu_decode_pf_bit 💖

okay so bestie, welcome to the llc_pdu_decode_pf_bit(9) page — yes it's a section 9 kernel API manual and yes it's lowkey iconic. this is the little function that goes digging in an LLC header and pulls out the poll/final bit for you. it's giving "small function, big responsibility" and we're obsessed 🫶

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🌸 NAME 🌸

llc_pdu_decode_pf_bit — grabs the poll/final bit out of an LLC header, no cap ✨

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🦋 SYNOPSIS 🦋

void llc_pdu_decode_pf_bit (struct sk_buff *skb , u8 *pf_bit );

that's it, that's the whole vibe. returns void, so don't go looking for a return value, there isn't one 💅

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🎀 ARGUMENTS 🎀

• skb — the input skb, aka the packet situation the p/f bit has to be extracted from. it's the main character here 👑
• pf_bit — the poll/final bit itself, which comes out as either 0 or 1. only those two, it's not complicated 🙈

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💜 DESCRIPTION 💜

so what this function actually does is extract the poll/final bit from the LLC header, and how it finds it depends on the type of PDU. different PDU, different bit location — iykyk 🌈

• In I pdus or S pdus, the p/f bit is the right bit of the fourth byte in the header.
• In U pdus, the p/f bit is the fifth bit of the third byte.

that's the whole treasure map bestie, two rules and you're done 🗺️✨

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🔥 SEE ALSO 🔥

Kernel file ./net/llc/llc_pdu.c — plus the entire friend group of functions that live near it, fr fr:

• llc_pdu_set_pf_bit(9)
• llc_pdu_init_as_disc_cmd(9)
• llc_pdu_init_as_i_cmd(9)
• llc_pdu_init_as_rej_cmd(9)
• llc_pdu_init_as_rnr_cmd(9)
• llc_pdu_init_as_rr_cmd(9)
• llc_pdu_init_as_sabme_cmd(9)
• llc_pdu_init_as_dm_rsp(9)
• llc_pdu_init_as_frmr_rsp(9)
• llc_pdu_init_as_rr_rsp(9)
• llc_pdu_init_as_rej_rsp(9)
• llc_pdu_init_as_rnr_rsp(9)
• llc_pdu_init_as_ua_rsp(9)
• llc_pdu_decode_pdu_type(9)
• llc_pdu_get_pf_bit(9)

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pro tip from me to you: if you ever forget which byte the p/f bit hides in, just reread DESCRIPTION. I pdus and S pdus? fourth byte, right bit. U pdus? third byte, fifth bit. write it on your hand, it's fine 💀

and that's the page!! mwah 💋 this beauty ships from the source ./net/llc and is dated October 2026 — go forth and decode those bits, bestie, you're gonna slay 🧚‍♀️⭐💖