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rcu: Remove "cpu" argument to rcu_needs_cpu()

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The "cpu" argument to rcu_needs_cpu() is always the current CPU, so drop
it.  This in turn allows the "cpu" argument to rcu_cpu_has_callbacks()
to be removed, which allows the uses of "cpu" in both functions to be
replaced with a this_cpu_ptr().  Again, the anticipated cross-CPU uses
of these functions has been replaced by NO_HZ_FULL.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
This commit is contained in:
Paul E. McKenney 2014-10-21 13:23:08 -07:00
parent 38200cf247
commit aa6da5140b
5 changed files with 11 additions and 11 deletions
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2
include/linux/rcupdate.h
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@ -1103,7 +1103,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
__kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))
#if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL) #if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL)
static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) static inline int rcu_needs_cpu(unsigned long *delta_jiffies)
{ {
*delta_jiffies = ULONG_MAX; *delta_jiffies = ULONG_MAX;
return 0; return 0;

2
include/linux/rcutree.h
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@ -32,7 +32,7 @@
void rcu_note_context_switch(void); void rcu_note_context_switch(void);
#ifndef CONFIG_RCU_NOCB_CPU_ALL #ifndef CONFIG_RCU_NOCB_CPU_ALL
int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies); int rcu_needs_cpu(unsigned long *delta_jiffies);
#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ #endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
void rcu_cpu_stall_reset(void); void rcu_cpu_stall_reset(void);

4
kernel/rcu/tree.c
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@ -3159,7 +3159,7 @@ static int rcu_pending(void)
* non-NULL, store an indication of whether all callbacks are lazy. * non-NULL, store an indication of whether all callbacks are lazy.
* (If there are no callbacks, all of them are deemed to be lazy.) * (If there are no callbacks, all of them are deemed to be lazy.)
*/ */
static int __maybe_unused rcu_cpu_has_callbacks(int cpu, bool *all_lazy) static int __maybe_unused rcu_cpu_has_callbacks(bool *all_lazy)
{ {
bool al = true; bool al = true;
bool hc = false; bool hc = false;
@ -3167,7 +3167,7 @@ static int __maybe_unused rcu_cpu_has_callbacks(int cpu, bool *all_lazy)
struct rcu_state *rsp; struct rcu_state *rsp;
for_each_rcu_flavor(rsp) { for_each_rcu_flavor(rsp) {
rdp = per_cpu_ptr(rsp->rda, cpu); rdp = this_cpu_ptr(rsp->rda);
if (!rdp->nxtlist) if (!rdp->nxtlist)
continue; continue;
hc = true; hc = true;

12
kernel/rcu/tree_plugin.h
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@ -1512,10 +1512,10 @@ static void rcu_prepare_kthreads(int cpu)
* any flavor of RCU. * any flavor of RCU.
*/ */
#ifndef CONFIG_RCU_NOCB_CPU_ALL #ifndef CONFIG_RCU_NOCB_CPU_ALL
int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) int rcu_needs_cpu(unsigned long *delta_jiffies)
{ {
*delta_jiffies = ULONG_MAX; *delta_jiffies = ULONG_MAX;
return rcu_cpu_has_callbacks(cpu, NULL); return rcu_cpu_has_callbacks(NULL);
} }
#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ #endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
@ -1624,15 +1624,15 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
* The caller must have disabled interrupts. * The caller must have disabled interrupts.
*/ */
#ifndef CONFIG_RCU_NOCB_CPU_ALL #ifndef CONFIG_RCU_NOCB_CPU_ALL
int rcu_needs_cpu(int cpu, unsigned long *dj) int rcu_needs_cpu(unsigned long *dj)
{ {
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
/* Snapshot to detect later posting of non-lazy callback. */ /* Snapshot to detect later posting of non-lazy callback. */
rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted; rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted;
/* If no callbacks, RCU doesn't need the CPU. */ /* If no callbacks, RCU doesn't need the CPU. */
if (!rcu_cpu_has_callbacks(cpu, &rdtp->all_lazy)) { if (!rcu_cpu_has_callbacks(&rdtp->all_lazy)) {
*dj = ULONG_MAX; *dj = ULONG_MAX;
return 0; return 0;
} }
@ -1679,7 +1679,7 @@ static void rcu_prepare_for_idle(int cpu)
/* Handle nohz enablement switches conservatively. */ /* Handle nohz enablement switches conservatively. */
tne = ACCESS_ONCE(tick_nohz_active); tne = ACCESS_ONCE(tick_nohz_active);
if (tne != rdtp->tick_nohz_enabled_snap) { if (tne != rdtp->tick_nohz_enabled_snap) {
if (rcu_cpu_has_callbacks(cpu, NULL)) if (rcu_cpu_has_callbacks(NULL))
invoke_rcu_core(); /* force nohz to see update. */ invoke_rcu_core(); /* force nohz to see update. */
rdtp->tick_nohz_enabled_snap = tne; rdtp->tick_nohz_enabled_snap = tne;
return; return;

2
kernel/time/tick-sched.c
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@ -585,7 +585,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
last_jiffies = jiffies; last_jiffies = jiffies;
} while (read_seqretry(&jiffies_lock, seq)); } while (read_seqretry(&jiffies_lock, seq));
if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || if (rcu_needs_cpu(&rcu_delta_jiffies) ||
arch_needs_cpu() || irq_work_needs_cpu()) { arch_needs_cpu() || irq_work_needs_cpu()) {
next_jiffies = last_jiffies + 1; next_jiffies = last_jiffies + 1;
delta_jiffies = 1; delta_jiffies = 1;