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| author | Paul E. McKenney <paulmck@kernel.org> | 2022-01-25 00:41:32 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-04-12 00:31:02 +0200 |
| commit | e2f638365dd6283b7df1cb5e82f5b2746359f062 (patch) | |
| tree | 0ef8c2583600ad1870fa6aea5e6c9ca49ae40358 /kernel/rcu/srcutree.c | |
| parent | srcu: Dynamically allocate srcu_node array (diff) | |
| download | linux-e2f638365dd6283b7df1cb5e82f5b2746359f062.tar.xz linux-e2f638365dd6283b7df1cb5e82f5b2746359f062.zip | |
srcu: Add size-state transitioning code
This is just dead code at the moment, and will be used once
the state-transition code is activated.
Because srcu_barrier() must be aware of transition before call_srcu(), the
state machine waits for an SRCU grace period before callbacks are queued
to the non-CPU-0 queues. This requres that portions of srcu_barrier()
be enclosed in an SRCU read-side critical section.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/srcutree.c')
| -rw-r--r-- | kernel/rcu/srcutree.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index e98cc218e42b..00f9aed6f7b9 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -562,6 +562,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) unsigned long mask; struct srcu_data *sdp; struct srcu_node *snp; + int ss_state; /* Prevent more than one additional grace period. */ mutex_lock(&ssp->srcu_cb_mutex); @@ -629,6 +630,15 @@ static void srcu_gp_end(struct srcu_struct *ssp) } else { spin_unlock_irq_rcu_node(ssp); } + + /* Transition to big if needed. */ + ss_state = smp_load_acquire(&ssp->srcu_size_state); + if (ss_state != SRCU_SIZE_SMALL && ss_state != SRCU_SIZE_BIG) { + if (ss_state == SRCU_SIZE_ALLOC) + init_srcu_struct_nodes(ssp); + else + smp_store_release(&ssp->srcu_size_state, ss_state + 1); + } } /* @@ -1178,6 +1188,7 @@ static void srcu_barrier_one_cpu(struct srcu_struct *ssp, struct srcu_data *sdp) void srcu_barrier(struct srcu_struct *ssp) { int cpu; + int idx; unsigned long s = rcu_seq_snap(&ssp->srcu_barrier_seq); check_init_srcu_struct(ssp); @@ -1193,11 +1204,13 @@ void srcu_barrier(struct srcu_struct *ssp) /* Initial count prevents reaching zero until all CBs are posted. */ atomic_set(&ssp->srcu_barrier_cpu_cnt, 1); + idx = srcu_read_lock(ssp); if (smp_load_acquire(&ssp->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER) srcu_barrier_one_cpu(ssp, per_cpu_ptr(ssp->sda, 0)); else for_each_possible_cpu(cpu) srcu_barrier_one_cpu(ssp, per_cpu_ptr(ssp->sda, cpu)); + srcu_read_unlock(ssp, idx); /* Remove the initial count, at which point reaching zero can happen. */ if (atomic_dec_and_test(&ssp->srcu_barrier_cpu_cnt)) |