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rcu/nocb: Consolidate rcu_nocb_cpu_offload/deoffload functions

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The rcu_nocb_cpu_offload() and rcu_nocb_cpu_deoffload() functions are
nearly duplicates.

Therefore, extract the common logic into rcu_nocb_cpu_toggle_offload()
which takes an 'offload' boolean, and make both exported functions
simple wrappers.

This eliminates a bunch of duplicate code at the call sites, namely
mutex locking, CPU hotplug locking and CPU online checks.

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
This commit is contained in:
Joel Fernandes 2026-01-03 10:37:54 -05:00
parent 3e3d7d8f3a
commit 18d01ff3b9
1 changed files with 35 additions and 35 deletions
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70
kernel/rcu/tree_nocb.h
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@ -1081,30 +1081,6 @@ static int rcu_nocb_rdp_deoffload(struct rcu_data *rdp)
return 0;
}
int rcu_nocb_cpu_deoffload(int cpu)
{
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
int ret = 0;
cpus_read_lock();
mutex_lock(&rcu_state.nocb_mutex);
if (rcu_rdp_is_offloaded(rdp)) {
if (!cpu_online(cpu)) {
ret = rcu_nocb_rdp_deoffload(rdp);
if (!ret)
cpumask_clear_cpu(cpu, rcu_nocb_mask);
} else {
pr_info("NOCB: Cannot CB-deoffload online CPU %d\n", rdp->cpu);
ret = -EINVAL;
}
}
mutex_unlock(&rcu_state.nocb_mutex);
cpus_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(rcu_nocb_cpu_deoffload);
static bool rcu_nocb_rdp_offload_wait_cond(struct rcu_data *rdp)
{
unsigned long flags;
@ -1149,28 +1125,52 @@ static int rcu_nocb_rdp_offload(struct rcu_data *rdp)
return 0;
}
int rcu_nocb_cpu_offload(int cpu)
/* Common helper for CPU offload/deoffload operations. */
static int rcu_nocb_cpu_toggle_offload(int cpu, bool offload)
{
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
int ret = 0;
cpus_read_lock();
mutex_lock(&rcu_state.nocb_mutex);
if (!rcu_rdp_is_offloaded(rdp)) {
if (!cpu_online(cpu)) {
ret = rcu_nocb_rdp_offload(rdp);
if (!ret)
cpumask_set_cpu(cpu, rcu_nocb_mask);
} else {
pr_info("NOCB: Cannot CB-offload online CPU %d\n", rdp->cpu);
ret = -EINVAL;
}
/* Already in desired state, nothing to do. */
if (rcu_rdp_is_offloaded(rdp) == offload)
goto out_unlock;
if (cpu_online(cpu)) {
pr_info("NOCB: Cannot CB-%soffload online CPU %d\n",
offload ? "" : "de", rdp->cpu);
ret = -EINVAL;
goto out_unlock;
}
if (offload) {
ret = rcu_nocb_rdp_offload(rdp);
if (!ret)
cpumask_set_cpu(cpu, rcu_nocb_mask);
} else {
ret = rcu_nocb_rdp_deoffload(rdp);
if (!ret)
cpumask_clear_cpu(cpu, rcu_nocb_mask);
}
out_unlock:
mutex_unlock(&rcu_state.nocb_mutex);
cpus_read_unlock();
return ret;
}
int rcu_nocb_cpu_deoffload(int cpu)
{
return rcu_nocb_cpu_toggle_offload(cpu, false /* de-offload */);
}
EXPORT_SYMBOL_GPL(rcu_nocb_cpu_deoffload);
int rcu_nocb_cpu_offload(int cpu)
{
return rcu_nocb_cpu_toggle_offload(cpu, true /* offload */);
}
EXPORT_SYMBOL_GPL(rcu_nocb_cpu_offload);
#ifdef CONFIG_RCU_LAZY