From 65b4a59557f6fb5d4355093ad5a2c1bd5598ee41 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 15 Feb 2024 09:04:30 -0800 Subject: srcu: Make Tiny SRCU explicitly disable preemption Because Tiny SRCU is used only in kernels built with either CONFIG_PREEMPT_NONE=y or CONFIG_PREEMPT_VOLUNTARY=y, there has not been any need for TINY SRCU to explicitly disable preemption. However, the prospect of lazy preemption changes that, and the lazy-preemption patches do result in rcutorture runs finding both too-short grace periods and grace-period hangs for Tiny SRCU. This commit therefore adds the needed preempt_disable() and preempt_enable() calls to Tiny SRCU. Signed-off-by: Paul E. McKenney Cc: Ankur Arora Cc: Thomas Gleixner Signed-off-by: Uladzislau Rezki (Sony) --- include/linux/srcutiny.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/srcutiny.h') diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h index 447133171d95..4d96bbdb45f0 100644 --- a/include/linux/srcutiny.h +++ b/include/linux/srcutiny.h @@ -64,8 +64,10 @@ static inline int __srcu_read_lock(struct srcu_struct *ssp) { int idx; + preempt_disable(); // Needed for PREEMPT_AUTO idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1; WRITE_ONCE(ssp->srcu_lock_nesting[idx], READ_ONCE(ssp->srcu_lock_nesting[idx]) + 1); + preempt_enable(); return idx; } -- cgit v1.2.3-59-g8ed1b