rcu: Remove rsp parameter from rcu_get_root()

There now is only one rcu_state structure in a given build of the
Linux kernel, so there is no need to pass it as a parameter to RCU's
functions.  This commit therefore removes the rsp parameter from
rcu_get_root().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 1a2956d..8d0e18f 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -623,9 +623,9 @@ EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
 /*
  * Return the root node of the specified rcu_state structure.
  */
-static struct rcu_node *rcu_get_root(struct rcu_state *rsp)
+static struct rcu_node *rcu_get_root(void)
 {
-       return &rsp->node[0];
+       return &rcu_state.node[0];
 }
 
 /*
@@ -1318,7 +1318,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gp_seq)
        unsigned long gpa;
        unsigned long j;
        int ndetected = 0;
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
        long totqlen = 0;
 
        /* Kick and suppress, if so configured. */
@@ -1367,7 +1367,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gp_seq)
                        pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n",
                               rsp->name, j - gpa, j, gpa,
                               jiffies_till_next_fqs,
-                              rcu_get_root(rsp)->qsmask);
+                              rcu_get_root()->qsmask);
                        /* In this case, the current CPU might be at fault. */
                        sched_show_task(current);
                }
@@ -1389,7 +1389,7 @@ static void print_cpu_stall(struct rcu_state *rsp)
        int cpu;
        unsigned long flags;
        struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
        long totqlen = 0;
 
        /* Kick and suppress, if so configured. */
@@ -1835,7 +1835,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
        unsigned long oldmask;
        unsigned long mask;
        struct rcu_data *rdp;
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
 
        WRITE_ONCE(rsp->gp_activity, jiffies);
        raw_spin_lock_irq_rcu_node(rnp);
@@ -1962,7 +1962,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
  */
 static bool rcu_gp_fqs_check_wake(struct rcu_state *rsp, int *gfp)
 {
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
 
        /* Someone like call_rcu() requested a force-quiescent-state scan. */
        *gfp = READ_ONCE(rsp->gp_flags);
@@ -1981,7 +1981,7 @@ static bool rcu_gp_fqs_check_wake(struct rcu_state *rsp, int *gfp)
  */
 static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time)
 {
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
 
        WRITE_ONCE(rsp->gp_activity, jiffies);
        rsp->n_force_qs++;
@@ -2010,7 +2010,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
        bool needgp = false;
        unsigned long new_gp_seq;
        struct rcu_data *rdp;
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
        struct swait_queue_head *sq;
 
        WRITE_ONCE(rsp->gp_activity, jiffies);
@@ -2058,7 +2058,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
                WRITE_ONCE(rsp->gp_activity, jiffies);
                rcu_gp_slow(rsp, gp_cleanup_delay);
        }
-       rnp = rcu_get_root(rsp);
+       rnp = rcu_get_root();
        raw_spin_lock_irq_rcu_node(rnp); /* GP before rsp->gp_seq update. */
 
        /* Declare grace period done. */
@@ -2094,7 +2094,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
        unsigned long j;
        int ret;
        struct rcu_state *rsp = arg;
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
 
        rcu_bind_gp_kthread();
        for (;;) {
@@ -2190,14 +2190,14 @@ static int __noreturn rcu_gp_kthread(void *arg)
  * which is released before return.
  */
 static void rcu_report_qs_rsp(unsigned long flags)
-       __releases(rcu_get_root(rsp)->lock)
+       __releases(rcu_get_root()->lock)
 {
        struct rcu_state *rsp = &rcu_state;
 
-       raw_lockdep_assert_held_rcu_node(rcu_get_root(rsp));
+       raw_lockdep_assert_held_rcu_node(rcu_get_root());
        WARN_ON_ONCE(!rcu_gp_in_progress());
        WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
-       raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);
+       raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(), flags);
        rcu_gp_kthread_wake(rsp);
 }
 
@@ -2654,7 +2654,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
                        return;
                rnp_old = rnp;
        }
-       /* rnp_old == rcu_get_root(rsp), rnp == NULL. */
+       /* rnp_old == rcu_get_root(), rnp == NULL. */
 
        /* Reached the root of the rcu_node tree, acquire lock. */
        raw_spin_lock_irqsave_rcu_node(rnp_old, flags);
@@ -2679,7 +2679,7 @@ rcu_check_gp_start_stall(struct rcu_state *rsp, struct rcu_node *rnp,
        const unsigned long gpssdelay = rcu_jiffies_till_stall_check() * HZ;
        unsigned long flags;
        unsigned long j;
-       struct rcu_node *rnp_root = rcu_get_root(rsp);
+       struct rcu_node *rnp_root = rcu_get_root();
        static atomic_t warned = ATOMIC_INIT(0);
 
        if (!IS_ENABLED(CONFIG_PROVE_RCU) || rcu_gp_in_progress() ||
@@ -3397,7 +3397,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
 {
        unsigned long flags;
        struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
 
        /* Set up local state, ensuring consistent view of global state. */
        raw_spin_lock_irqsave_rcu_node(rnp, flags);
@@ -3646,7 +3646,7 @@ static void rcu_migrate_callbacks(int cpu, struct rcu_state *rsp)
        unsigned long flags;
        struct rcu_data *my_rdp;
        struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
-       struct rcu_node *rnp_root = rcu_get_root(rdp->rsp);
+       struct rcu_node *rnp_root = rcu_get_root();
        bool needwake;
 
        if (rcu_is_nocb_cpu(cpu) || rcu_segcblist_empty(&rdp->cblist))
@@ -3744,7 +3744,7 @@ static int __init rcu_spawn_gp_kthread(void)
        for_each_rcu_flavor(rsp) {
                t = kthread_create(rcu_gp_kthread, rsp, "%s", rsp->name);
                BUG_ON(IS_ERR(t));
-               rnp = rcu_get_root(rsp);
+               rnp = rcu_get_root();
                raw_spin_lock_irqsave_rcu_node(rnp, flags);
                rsp->gp_kthread = t;
                if (kthread_prio) {

diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 298a690..0bcbb03 100644 (file)
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -288,7 +288,7 @@ static bool exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
 {
        struct rcu_data *rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id());
        struct rcu_node *rnp = rdp->mynode;
-       struct rcu_node *rnp_root = rcu_get_root(rsp);
+       struct rcu_node *rnp_root = rcu_get_root();
 
        /* Low-contention fastpath. */
        if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s) &&
@@ -479,7 +479,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
        unsigned long mask;
        int ndetected;
        struct rcu_node *rnp;
-       struct rcu_node *rnp_root = rcu_get_root(rsp);
+       struct rcu_node *rnp_root = rcu_get_root();
        int ret;
 
        trace_rcu_exp_grace_period(rsp->name, rcu_exp_gp_seq_endval(rsp), TPS("startwait"));
@@ -643,7 +643,7 @@ static void _synchronize_rcu_expedited(struct rcu_state *rsp,
 
        /* Wait for expedited grace period to complete. */
        rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id());
-       rnp = rcu_get_root(rsp);
+       rnp = rcu_get_root();
        wait_event(rnp->exp_wq[rcu_seq_ctr(s) & 0x3],
                   sync_exp_work_done(rsp, s));
        smp_mb(); /* Workqueue actions happen before return. */

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 99f5170..545e4ac 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -685,7 +685,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
  */
 static void rcu_print_detail_task_stall(struct rcu_state *rsp)
 {
-       struct rcu_node *rnp = rcu_get_root(rsp);
+       struct rcu_node *rnp = rcu_get_root();
 
        rcu_print_detail_task_stall_rnp(rnp);
        rcu_for_each_leaf_node(rsp, rnp)