From: Sebastian Andrzej Siewior Date: Thu, 12 Oct 2017 18:37:12 +0200 Subject: [PATCH] srcu: replace local_irqsave() with a locallock Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.10-rt5.tar.xz There are two instances which disable interrupts in order to become a stable this_cpu_ptr() pointer. The restore part is coupled with spin_unlock_irqrestore() which does not work on RT. Replace the local_irq_save() call with the appropriate local_lock() version of it. Signed-off-by: Sebastian Andrzej Siewior --- kernel/rcu/srcutree.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -25,6 +25,7 @@ #include #include #include +#include #include "rcu.h" #include "rcu_segcblist.h" @@ -735,6 +736,7 @@ static void srcu_flip(struct srcu_struct smp_mb(); /* D */ /* Pairs with C. */ } +static DEFINE_LOCAL_IRQ_LOCK(sp_llock); /* * If SRCU is likely idle, return true, otherwise return false. * @@ -764,13 +766,13 @@ static bool srcu_might_be_idle(struct sr unsigned long t; /* If the local srcu_data structure has callbacks, not idle. */ - local_irq_save(flags); + local_lock_irqsave(sp_llock, flags); sdp = this_cpu_ptr(ssp->sda); if (rcu_segcblist_pend_cbs(&sdp->srcu_cblist)) { - local_irq_restore(flags); + local_unlock_irqrestore(sp_llock, flags); return false; /* Callbacks already present, so not idle. */ } - local_irq_restore(flags); + local_unlock_irqrestore(sp_llock, flags); /* * No local callbacks, so probabalistically probe global state. @@ -850,7 +852,7 @@ void __call_srcu(struct srcu_struct *ssp } rhp->func = func; idx = srcu_read_lock(ssp); - local_irq_save(flags); + local_lock_irqsave(sp_llock, flags); sdp = this_cpu_ptr(ssp->sda); spin_lock_rcu_node(sdp); rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp, false); @@ -866,7 +868,8 @@ void __call_srcu(struct srcu_struct *ssp sdp->srcu_gp_seq_needed_exp = s; needexp = true; } - spin_unlock_irqrestore_rcu_node(sdp, flags); + spin_unlock_rcu_node(sdp); + local_unlock_irqrestore(sp_llock, flags); if (needgp) srcu_funnel_gp_start(ssp, sdp, s, do_norm); else if (needexp)