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Merge branches 'fixes.2015.07.22a' and 'initexp.2015.08.04a' into HEAD

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fixes.2015.07.22a: Miscellaneous fixes.
initexp.2015.08.04a: Initialization and expedited updates.
	(Single branch due to conflicts.)
This commit is contained in:
Paul E. McKenney
2015-08-04 08:40:58 -07:00
parent 9a54f98e34 af859beaab
commit 8ff4fbfd69
20 changed files with 435 additions and 476 deletions
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117
kernel/rcu/tree_plugin.h
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@@ -82,10 +82,8 @@ static void __init rcu_bootup_announce_oddness(void)
pr_info("\tRCU lockdep checking is enabled.\n");
if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_RUNNABLE))
pr_info("\tRCU torture testing starts during boot.\n");
if (IS_ENABLED(CONFIG_RCU_CPU_STALL_INFO))
pr_info("\tAdditional per-CPU info printed with stalls.\n");
if (NUM_RCU_LVL_4 != 0)
pr_info("\tFour-level hierarchy is enabled.\n");
if (RCU_NUM_LVLS >= 4)
pr_info("\tFour(or more)-level hierarchy is enabled.\n");
if (RCU_FANOUT_LEAF != 16)
pr_info("\tBuild-time adjustment of leaf fanout to %d.\n",
RCU_FANOUT_LEAF);
@@ -418,8 +416,6 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp)
rcu_print_detail_task_stall_rnp(rnp);
}
#ifdef CONFIG_RCU_CPU_STALL_INFO
static void rcu_print_task_stall_begin(struct rcu_node *rnp)
{
pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):",
@@ -431,18 +427,6 @@ static void rcu_print_task_stall_end(void)
pr_cont("\n");
}
#else /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
static void rcu_print_task_stall_begin(struct rcu_node *rnp)
{
}
static void rcu_print_task_stall_end(void)
{
}
#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_INFO */
/*
* Scan the current list of tasks blocked within RCU read-side critical
* sections, printing out the tid of each.
@@ -552,8 +536,6 @@ void synchronize_rcu(void)
EXPORT_SYMBOL_GPL(synchronize_rcu);
static DECLARE_WAIT_QUEUE_HEAD(sync_rcu_preempt_exp_wq);
static unsigned long sync_rcu_preempt_exp_count;
static DEFINE_MUTEX(sync_rcu_preempt_exp_mutex);
/*
* Return non-zero if there are any tasks in RCU read-side critical
@@ -573,7 +555,7 @@ static int rcu_preempted_readers_exp(struct rcu_node *rnp)
* for the current expedited grace period. Works only for preemptible
* RCU -- other RCU implementation use other means.
*
* Caller must hold sync_rcu_preempt_exp_mutex.
* Caller must hold the root rcu_node's exp_funnel_mutex.
*/
static int sync_rcu_preempt_exp_done(struct rcu_node *rnp)
{
@@ -589,7 +571,7 @@ static int sync_rcu_preempt_exp_done(struct rcu_node *rnp)
* recursively up the tree. (Calm down, calm down, we do the recursion
* iteratively!)
*
* Caller must hold sync_rcu_preempt_exp_mutex.
* Caller must hold the root rcu_node's exp_funnel_mutex.
*/
static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
bool wake)
@@ -628,7 +610,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
* set the ->expmask bits on the leaf rcu_node structures to tell phase 2
* that work is needed here.
*
* Caller must hold sync_rcu_preempt_exp_mutex.
* Caller must hold the root rcu_node's exp_funnel_mutex.
*/
static void
sync_rcu_preempt_exp_init1(struct rcu_state *rsp, struct rcu_node *rnp)
@@ -671,7 +653,7 @@ sync_rcu_preempt_exp_init1(struct rcu_state *rsp, struct rcu_node *rnp)
* invoke rcu_report_exp_rnp() to clear out the upper-level ->expmask bits,
* enabling rcu_read_unlock_special() to do the bit-clearing.
*
* Caller must hold sync_rcu_preempt_exp_mutex.
* Caller must hold the root rcu_node's exp_funnel_mutex.
*/
static void
sync_rcu_preempt_exp_init2(struct rcu_state *rsp, struct rcu_node *rnp)
@@ -719,51 +701,17 @@ sync_rcu_preempt_exp_init2(struct rcu_state *rsp, struct rcu_node *rnp)
void synchronize_rcu_expedited(void)
{
struct rcu_node *rnp;
struct rcu_node *rnp_unlock;
struct rcu_state *rsp = rcu_state_p;
unsigned long snap;
int trycount = 0;
unsigned long s;
smp_mb(); /* Caller's modifications seen first by other CPUs. */
snap = READ_ONCE(sync_rcu_preempt_exp_count) + 1;
smp_mb(); /* Above access cannot bleed into critical section. */
s = rcu_exp_gp_seq_snap(rsp);
/*
* Block CPU-hotplug operations. This means that any CPU-hotplug
* operation that finds an rcu_node structure with tasks in the
* process of being boosted will know that all tasks blocking
* this expedited grace period will already be in the process of
* being boosted. This simplifies the process of moving tasks
* from leaf to root rcu_node structures.
*/
if (!try_get_online_cpus()) {
/* CPU-hotplug operation in flight, fall back to normal GP. */
wait_rcu_gp(call_rcu);
return;
}
rnp_unlock = exp_funnel_lock(rsp, s);
if (rnp_unlock == NULL)
return; /* Someone else did our work for us. */
/*
* Acquire lock, falling back to synchronize_rcu() if too many
* lock-acquisition failures. Of course, if someone does the
* expedited grace period for us, just leave.
*/
while (!mutex_trylock(&sync_rcu_preempt_exp_mutex)) {
if (ULONG_CMP_LT(snap,
READ_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto mb_ret; /* Others did our work for us. */
}
if (trycount++ < 10) {
udelay(trycount * num_online_cpus());
} else {
put_online_cpus();
wait_rcu_gp(call_rcu);
return;
}
}
if (ULONG_CMP_LT(snap, READ_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto unlock_mb_ret; /* Others did our work for us. */
}
rcu_exp_gp_seq_start(rsp);
/* force all RCU readers onto ->blkd_tasks lists. */
synchronize_sched_expedited();
@@ -779,20 +727,14 @@ void synchronize_rcu_expedited(void)
rcu_for_each_leaf_node(rsp, rnp)
sync_rcu_preempt_exp_init2(rsp, rnp);
put_online_cpus();
/* Wait for snapshotted ->blkd_tasks lists to drain. */
rnp = rcu_get_root(rsp);
wait_event(sync_rcu_preempt_exp_wq,
sync_rcu_preempt_exp_done(rnp));
/* Clean up and exit. */
smp_mb(); /* ensure expedited GP seen before counter increment. */
WRITE_ONCE(sync_rcu_preempt_exp_count, sync_rcu_preempt_exp_count + 1);
unlock_mb_ret:
mutex_unlock(&sync_rcu_preempt_exp_mutex);
mb_ret:
smp_mb(); /* ensure subsequent action seen after grace period. */
rcu_exp_gp_seq_end(rsp);
mutex_unlock(&rnp_unlock->exp_funnel_mutex);
}
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
@@ -1703,8 +1645,6 @@ early_initcall(rcu_register_oom_notifier);
#endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */
#ifdef CONFIG_RCU_CPU_STALL_INFO
#ifdef CONFIG_RCU_FAST_NO_HZ
static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
@@ -1793,33 +1733,6 @@ static void increment_cpu_stall_ticks(void)
raw_cpu_inc(rsp->rda->ticks_this_gp);
}
#else /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
static void print_cpu_stall_info_begin(void)
{
pr_cont(" {");
}
static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
{
pr_cont(" %d", cpu);
}
static void print_cpu_stall_info_end(void)
{
pr_cont("} ");
}
static void zero_cpu_stall_ticks(struct rcu_data *rdp)
{
}
static void increment_cpu_stall_ticks(void)
{
}
#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_INFO */
#ifdef CONFIG_RCU_NOCB_CPU
/*