write_seqlock(9)

💅 write_seqlock(9) — a Kernel API Manual moment

okay so first of all, bestie, this page lives in the Kernel API Manual and it's about write_seqlock. yes the name is a mouthful, no we're not skipping it, it's iconic. ✨

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🌸 NAME

write_seqlock — start a seqlock_t write side critical section

like, you're opening the write side of the party. main character energy only.

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🎀 SYNOPSIS

void write_seqlock (seqlock_t *sl );

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💖 ARGUMENTS

• sl — pointer to seqlock_t. that's it. that's the whole argument list. she's low maintenance.

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✨ DESCRIPTION

write_seqlock opens a write side critical section for the given seqlock_t. periodt.

and like, it also implicitly acquires the spinlock_t embedded inside that sequential lock — so it's doing two things at once, multi-tasking queen 🫶. because of that, all seqlock_t write side sections are automatically serialized and non-preemptible. no cap, that's just how she runs.

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🦋 CONTEXT

okay this is the important bit, so listen up 🙈 — if the seqlock_t read section, or other write side critical sections, can be invoked from hardirq or softirq contexts, use the _irqsave or _bh variants of this function instead.

like literally do not rawdog the plain version in irq context, bestie, that's not the vibe 💀

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👑 SEE ALSO

Kernel file ./include/linux/seqlock.h and honestly her whole extended 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_begin(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_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)

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k bye bestie, this page came from ./include/linux and it's dated October 2026, and yes we're still calling it write_seqlock(9) because consistency is cute 💅✨