lock_sock_fast(9)

💅 lock_sock_fast(9) — like, the fast version of lock_sock, bestie

okay so this page lives in the Kernel API Manual (section 9, kernel developer vibes only 🧚) and it's about one lil function that's gonna save you so much time if you respect its rules. let's get into it ✨

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🌸 NAME 🌸

lock_sock_fast — the fast version of lock_sock. that's it, that's the whole name. short, sweet, iconic 👑

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🦋 SYNOPSIS 🦋

bool lock_sock_fast (struct sock *sk );

literally one argument, returns a bool, no cap. 🫶

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🎀 ARGUMENTS 🎀

• sk — the socket. that's the whole description, she's lowkey mysterious like that 🙈

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✨ DESCRIPTION ✨

okay bestie, listen carefully because this one has rules 💀

you should only use this version for a very small section, where the process won't block. like, in-and-out, blink-and-you-miss-it energy. if it's a big sprawling critical section, this is not the function for you, go use the regular one, i'm begging 😭

it returns false if the fast path is taken, and here's exactly what the world looks like in that case:

• sk_lock.slock is locked
• owned = 0
• BH disabled

it returns true if the slow path is taken, and then the state flips to:

• sk_lock.slock is unlocked
• owned = 1
• BH enabled

so yeah — false = fast path, true = slow path. yes, it's a little upside-down from what your brain wants, no i don't make the rules 💅 write it down. put it on a sticky note. put it on your forehead, idc, just don't get it backwards.

⚠️ fr fr: small section only, and only where the process won't block. that's the whole deal you're making with this function.

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🔥 SEE ALSO 🔥

all the related lore lives in the kernel file ./include/net/sock.h, and these are the siblings/cousins/friends-of-friends you might wanna check out:

• struct sock_common(9)
• struct sock(9)
• sk_user_data_is_nocopy(9)
• __locked_read_sk_user_data_with_flags(9)
• __rcu_dereference_sk_user_data_with_flags(9)
• sk_for_each_entry_offset_rcu(9)
• SOCK_CONNECT_BIND(9)
• unlock_sock_fast(9)
• sk_wmem_alloc_get(9)
• sk_rmem_alloc_get(9)
• sk_has_allocations(9)
• skwq_has_sleeper(9)
• sock_poll_wait(9)
• sk_page_frag(9)
• _sock_tx_timestamp(9)
• sk_eat_skb(9)

(and yes, unlock_sock_fast(9) is right there — she's the other half of the duo, don't leave her hanging 🫶)

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🌈 sign-off 🌈

bestie this page comes to you from the ./include/net directory, dated October 2026, and it's literally titled lock_sock_fast(9) under the Kernel API Manual. go forth, lock fast, stay tiny, and remember: small section, no blocking, and always check your return value 💖✨🎀