On Thu, May 07, 2026 at 09:21:03PM -0700, Boqun Feng wrote: > From: Boqun Feng <[email protected]> > > In order to use preempt_count() to tracking the interrupt disable > nesting level, __preempt_count_{add,sub}_return() are introduced, as > their name suggest, these primitives return the new value of the > preempt_count() after changing it. The following example shows the usage > of it in local_interrupt_disable(): > > // increase the HARDIRQ_DISABLE bit > new_count = __preempt_count_add_return(HARDIRQ_DISABLE_OFFSET); > > // if it's the first-time increment, then disable the interrupt > // at hardware level. > if (new_count & HARDIRQ_DISABLE_MASK == HARDIRQ_DISABLE_OFFSET) { > local_irq_save(flags); > raw_cpu_write(local_interrupt_disable_state.flags, flags); > } > > Having these primitives will avoid a read of preempt_count() after > changing preempt_count() on certain architectures. > > Signed-off-by: Boqun Feng <[email protected]> > Signed-off-by: Boqun Feng <[email protected]> > Link: https://patch.msgid.link/[email protected] > --- > arch/arm64/include/asm/preempt.h | 18 ++++++++++++++++++ > arch/s390/include/asm/preempt.h | 10 ++++++++++ > arch/x86/include/asm/preempt.h | 10 ++++++++++ > include/asm-generic/preempt.h | 14 ++++++++++++++ > 4 files changed, 52 insertions(+)
fwiw: Acked-by: Heiko Carstens <[email protected]> # s390
