write_seqcount_begin(9)

💅 write_seqcount_begin(9) 💅

okay so bestie, welcome to the kernel API manual — this one's a (9) page, and it's about write_seqcount_begin. it lives at ./include/linux and it's dated October 2026, so like… future girl math but make it concurrency 🕰️✨

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🌸 NAME 🌸

write_seqcount_begin — start a seqcount_t write side critical section. that's it. that's the whole vibe check. you're opening the writer's door 🔑

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✨ SYNOPSIS ✨

write_seqcount_begin (s );

literally just hand it s and go, no cap 🫶

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🎀 ARGUMENTS 🎀

• s — pointer to a seqcount_t, or honestly any of the seqcount_LOCKNAME_t variants 💖 (yes queen, the whole little family is welcome)

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🦋 CONTEXT 🦋

okay this part is the important part, so like, pay attention bestie 👀 sequence counter write side sections must be serialized and non-preemptible. that's not a suggestion, that's the law 📜

preemption gets automatically disabled if and only if the seqcount write serialization lock is associated and preemptible. if and only if!! conditional queen 🎀

and if readers can be invoked from hardirq or softirq context? then interrupts or bottom halves must be respectively disabled. respectively!! keep that straight 💀

don't skip the context rules, i'm literally begging — getting this wrong is giving undefined behaviour energy and nobody wants that 😭

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🔥 SEE ALSO 🔥

kernel file ./include/linux/seqlock.h and the whole entire friend group:

• seqcount_init(9)
• SEQCNT_ZERO(9)
• __read_seqcount_begin(9)
• raw_read_seqcount_begin(9)
• read_seqcount_begin(9)
• raw_read_seqcount(9)
• raw_seqcount_try_begin(9)
• raw_seqcount_begin(9)
• __read_seqcount_retry(9)
• read_seqcount_retry(9)
• raw_write_seqcount_begin(9)
• raw_write_seqcount_end(9)
• write_seqcount_begin_nested(9)
• write_seqcount_end(9)
• raw_write_seqcount_barrier(9)
• write_seqcount_invalidate(9)
• SEQCNT_LATCH_ZERO(9)
• seqcount_latch_init(9)
• raw_read_seqcount_latch(9)
• read_seqcount_latch(9)
• raw_read_seqcount_latch_retry(9)
• read_seqcount_latch_retry(9)
• raw_write_seqcount_latch(9)
• write_seqcount_latch_begin(9)
• write_seqcount_latch(9)
• write_seqcount_latch_end(9)
• seqlock_init(9)
• DEFINE_SEQLOCK(9)
• read_seqbegin(9)
• read_seqretry(9)
• write_seqlock(9)
• write_sequnlock(9)
• write_seqlock_bh(9)
• write_sequnlock_bh(9)
• write_seqlock_irq(9)
• write_sequnlock_irq(9)
• write_seqlock_irqsave(9)
• write_sequnlock_irqrestore(9)
• read_seqlock_excl(9)
• read_sequnlock_excl(9)
• read_seqlock_excl_bh(9)
• read_sequnlock_excl_bh(9)
• read_seqlock_excl_irq(9)
• read_sequnlock_excl_irq(9)
• read_seqlock_excl_irqsave(9)
• read_sequnlock_excl_irqrestore(9)
• read_seqbegin_or_lock(9)
• need_seqretry(9)
• done_seqretry(9)
• read_seqbegin_or_lock_irqsave(9)
• done_seqretry_irqrestore(9)
• scoped_seqlock_read(9)

like, the whole friend group showed up to the function 💅 iconic turnout, honestly 🌈

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okay that's the page!! mwah 💋 this has been write_seqcount_begin(9) from the kernel API manual, sourced from ./include/linux and dated October 2026 — go forth and serialize your write side sections, bestie, i believe in you 🧚💜