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rcu/nocb: Add checks for offloaded callback processing 

This commit is a preparatory patch for offloaded callbacks using the
same ->cblist structure used by non-offloaded callbacks.  It therefore
adds rcu_segcblist_is_offloaded() calls where they will be needed when
!rcu_segcblist_is_enabled() no longer flags the offloaded case.  It also
adds checks in rcu_do_batch() to ensure that there are no missed checks:
Currently, it should not be possible for offloaded execution to reach
rcu_do_batch(), though this will change later in this series.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
This commit is contained in:
Paul E. McKenney 2019-04-16 08:19:43 -07:00
parent ce5215c134
commit 750d7f6a43
1 changed files with 8 additions and 3 deletions
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11
kernel/rcu/tree.c
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@ -210,7 +210,8 @@ static long rcu_get_n_cbs_cpu(int cpu)
{
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
if (rcu_segcblist_is_enabled(&rdp->cblist)) /* Online normal CPU? */
if (rcu_segcblist_is_enabled(&rdp->cblist) &&
!rcu_segcblist_is_offloaded(&rdp->cblist)) /* Online normal CPU? */
return rcu_segcblist_n_cbs(&rdp->cblist);
return rcu_get_n_cbs_nocb_cpu(rdp); /* Works for offline, too. */
}
@ -2081,6 +2082,7 @@ static void rcu_do_batch(struct rcu_data *rdp)
struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
long bl, count;
WARN_ON_ONCE(rdp->cblist.offloaded);
/* If no callbacks are ready, just return. */
if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
trace_rcu_batch_start(rcu_state.name,
@ -2299,7 +2301,8 @@ static __latent_entropy void rcu_core(void)
/* No grace period and unregistered callbacks? */
if (!rcu_gp_in_progress() &&
rcu_segcblist_is_enabled(&rdp->cblist)) {
rcu_segcblist_is_enabled(&rdp->cblist) &&
!rcu_segcblist_is_offloaded(&rdp->cblist)) {
local_irq_save(flags);
if (!rcu_segcblist_restempty(&rdp->cblist, RCU_NEXT_READY_TAIL))
rcu_accelerate_cbs_unlocked(rnp, rdp);
@ -2514,7 +2517,8 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func, int cpu, bool lazy)
rdp = this_cpu_ptr(&rcu_data);
/* Add the callback to our list. */
if (unlikely(!rcu_segcblist_is_enabled(&rdp->cblist)) || cpu != -1) {
if (unlikely(!rcu_segcblist_is_enabled(&rdp->cblist)) ||
rcu_segcblist_is_offloaded(&rdp->cblist) || cpu != -1) {
int offline;
if (cpu != -1)
@ -2750,6 +2754,7 @@ static int rcu_pending(void)
/* Has RCU gone idle with this CPU needing another grace period? */
if (!rcu_gp_in_progress() &&
rcu_segcblist_is_enabled(&rdp->cblist) &&
!rcu_segcblist_is_offloaded(&rdp->cblist) &&
!rcu_segcblist_restempty(&rdp->cblist, RCU_NEXT_READY_TAIL))
return 1;