From 77a40f97030b27b3fc1640a3ed203870f0817f57 Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Fri, 30 Aug 2019 12:36:32 -0400 Subject: rcu: Remove kfree_rcu() special casing and lazy-callback handling This commit removes kfree_rcu() special-casing and the lazy-callback handling from Tree RCU. It moves some of this special casing to Tiny RCU, the removal of which will be the subject of later commits. This results in a nice negative delta. Suggested-by: Paul E. McKenney Signed-off-by: Joel Fernandes (Google) [ paulmck: Add slab.h #include, thanks to kbuild test robot . ] Signed-off-by: Paul E. McKenney --- kernel/rcu/srcutree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/rcu/srcutree.c') diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 5dffade2d7cd..d0a9d5b69087 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -853,7 +853,7 @@ static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp, local_irq_save(flags); sdp = this_cpu_ptr(ssp->sda); spin_lock_rcu_node(sdp); - rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp, false); + rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp); rcu_segcblist_advance(&sdp->srcu_cblist, rcu_seq_current(&ssp->srcu_gp_seq)); s = rcu_seq_snap(&ssp->srcu_gp_seq); @@ -1052,7 +1052,7 @@ void srcu_barrier(struct srcu_struct *ssp) sdp->srcu_barrier_head.func = srcu_barrier_cb; debug_rcu_head_queue(&sdp->srcu_barrier_head); if (!rcu_segcblist_entrain(&sdp->srcu_cblist, - &sdp->srcu_barrier_head, 0)) { + &sdp->srcu_barrier_head)) { debug_rcu_head_unqueue(&sdp->srcu_barrier_head); atomic_dec(&ssp->srcu_barrier_cpu_cnt); } -- cgit v1.2.3 From 844a378de3372c923909681706d62336d702531e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 4 Nov 2019 08:08:30 -0800 Subject: srcu: Apply *_ONCE() to ->srcu_last_gp_end The ->srcu_last_gp_end field is accessed from any CPU at any time by synchronize_srcu(), so non-initialization references need to use READ_ONCE() and WRITE_ONCE(). This commit therefore makes that change. Reported-by: syzbot+08f3e9d26e5541e1ecf2@syzkaller.appspotmail.com Acked-by: Marco Elver Signed-off-by: Paul E. McKenney --- kernel/rcu/srcutree.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'kernel/rcu/srcutree.c') diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 5dffade2d7cd..21acdff3bd27 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -530,7 +530,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) idx = rcu_seq_state(ssp->srcu_gp_seq); WARN_ON_ONCE(idx != SRCU_STATE_SCAN2); cbdelay = srcu_get_delay(ssp); - ssp->srcu_last_gp_end = ktime_get_mono_fast_ns(); + WRITE_ONCE(ssp->srcu_last_gp_end, ktime_get_mono_fast_ns()); rcu_seq_end(&ssp->srcu_gp_seq); gpseq = rcu_seq_current(&ssp->srcu_gp_seq); if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, gpseq)) @@ -762,6 +762,7 @@ static bool srcu_might_be_idle(struct srcu_struct *ssp) unsigned long flags; struct srcu_data *sdp; unsigned long t; + unsigned long tlast; /* If the local srcu_data structure has callbacks, not idle. */ local_irq_save(flags); @@ -780,9 +781,9 @@ static bool srcu_might_be_idle(struct srcu_struct *ssp) /* First, see if enough time has passed since the last GP. */ t = ktime_get_mono_fast_ns(); + tlast = READ_ONCE(ssp->srcu_last_gp_end); if (exp_holdoff == 0 || - time_in_range_open(t, ssp->srcu_last_gp_end, - ssp->srcu_last_gp_end + exp_holdoff)) + time_in_range_open(t, tlast, tlast + exp_holdoff)) return false; /* Too soon after last GP. */ /* Next, check for probable idleness. */ -- cgit v1.2.3