__read_seqcount_retry(9)

🦋 __read_seqcount_retry(9) — Kernel API Manual 🦋

💖 NAME 💖

__read_seqcount_retry — end a seqcount_t read section w/o barrier

✨ SYNOPSIS ✨

__read_seqcount_retry (s , start );

🎀 ARGUMENTS 🎀

• s — pointer to seqcount_t or any of the seqcount_LOCKNAME_t variants.
• start — count, from read_seqcount_begin.

🦋 DESCRIPTION 🦋

Okay so __read_seqcount_retry is giving read_seqcount_retry energy, but it has no smp_rmb barrier. No barrier, no cap. Callers should ensure that smp_rmb or equivalent ordering is provided before actually loading any of the variables that are to be protected in this critical section.

Use carefully, only in critical code, and comment how the barrier is provided. 💅

🌈 RETURN 🌈

true if a read section retry is required, else false. Lowkey simple, bestie.

👑 SEE ALSO 👑

Kernel file: ./include/linux/seqlock.h — the whole seqlock 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)
• 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_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)

okay bye bestie! 🫶✨ this page is sourced from ./include/linux, dated October 2026, and it's all about __read_seqcount_retry(9) 🎀