xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

rcu: Abstract rcu_start_future_gp() from rcu_nocb_wait_gp()

Browse Source 
CPUs going idle will need to record the need for a future grace
period, but won't actually need to block waiting on it.  This commit
therefore splits rcu_start_future_gp(), which does the recording, from
rcu_nocb_wait_gp(), which now invokes rcu_start_future_gp() to do the
recording, after which rcu_nocb_wait_gp() does the waiting.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
2012-12-30 15:21:01 -08:00
committed by Paul E. McKenney
parent 8b425aa8f1
commit 0446be4897
3 changed files with 130 additions and 99 deletions
Download Patch File Download Diff File Expand all files Collapse all files

104
kernel/rcutree_plugin.h
View File

@@ -2022,22 +2022,12 @@ static int rcu_nocb_needs_gp(struct rcu_state *rsp)
}
/*
* Clean up this rcu_node structure's no-CBs state at the end of
* a grace period, and also return whether any no-CBs CPU associated
* with this rcu_node structure needs another grace period.
* Wake up any no-CBs CPUs' kthreads that were waiting on the just-ended
* grace period.
*/
static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
{
int c = rnp->completed;
int needmore;
wake_up_all(&rnp->nocb_gp_wq[c & 0x1]);
rnp->need_future_gp[c & 0x1] = 0;
needmore = rnp->need_future_gp[(c + 1) & 0x1];
trace_rcu_future_grace_period(rsp->name, rnp->gpnum, rnp->completed,
c, rnp->level, rnp->grplo, rnp->grphi,
needmore ? "CleanupMore" : "Cleanup");
return needmore;
wake_up_all(&rnp->nocb_gp_wq[rnp->completed & 0x1]);
}
/*
@@ -2175,84 +2165,16 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
bool d;
unsigned long flags;
struct rcu_node *rnp = rdp->mynode;
struct rcu_node *rnp_root = rcu_get_root(rdp->rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);
c = rnp->completed + 2;
/* Count our request for a grace period. */
rnp->need_future_gp[c & 0x1]++;
trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
rnp->completed, c, rnp->level,
rnp->grplo, rnp->grphi, "Startleaf");
if (rnp->gpnum != rnp->completed) {
/*
* This rcu_node structure believes that a grace period
* is in progress, so we are done. When this grace
* period ends, our request will be acted upon.
*/
trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
rnp->completed, c, rnp->level,
rnp->grplo, rnp->grphi,
"Startedleaf");
raw_spin_unlock_irqrestore(&rnp->lock, flags);
} else {
/*
* Might not be a grace period, check root rcu_node
* structure to see if we must start one.
*/
if (rnp != rnp_root)
raw_spin_lock(&rnp_root->lock); /* irqs disabled. */
if (rnp_root->gpnum != rnp_root->completed) {
trace_rcu_future_grace_period(rdp->rsp->name,
rnp->gpnum,
rnp->completed,
c, rnp->level,
rnp->grplo, rnp->grphi,
"Startedleafroot");
raw_spin_unlock(&rnp_root->lock); /* irqs disabled. */
} else {
/*
* No grace period, so we need to start one.
* The good news is that we can wait for exactly
* one grace period instead of part of the current
* grace period and all of the next grace period.
* Adjust counters accordingly and start the
* needed grace period.
*/
rnp->need_future_gp[c & 0x1]--;
c = rnp_root->completed + 1;
rnp->need_future_gp[c & 0x1]++;
rnp_root->need_future_gp[c & 0x1]++;
trace_rcu_future_grace_period(rdp->rsp->name,
rnp->gpnum,
rnp->completed,
c, rnp->level,
rnp->grplo, rnp->grphi,
"Startedroot");
rcu_start_gp(rdp->rsp);
raw_spin_unlock(&rnp->lock);
}
/* Clean up locking and irq state. */
if (rnp != rnp_root)
raw_spin_unlock_irqrestore(&rnp->lock, flags);
else
local_irq_restore(flags);
}
c = rcu_start_future_gp(rnp, rdp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
/*
* Wait for the grace period. Do so interruptibly to avoid messing
* up the load average.
*/
trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
rnp->completed, c, rnp->level,
rnp->grplo, rnp->grphi, "StartWait");
trace_rcu_future_gp(rnp, rdp, c, "StartWait");
for (;;) {
wait_event_interruptible(
rnp->nocb_gp_wq[c & 0x1],
@@ -2260,14 +2182,9 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
if (likely(d))
break;
flush_signals(current);
trace_rcu_future_grace_period(rdp->rsp->name,
rnp->gpnum, rnp->completed, c,
rnp->level, rnp->grplo,
rnp->grphi, "ResumeWait");
trace_rcu_future_gp(rnp, rdp, c, "ResumeWait");
}
trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
rnp->completed, c, rnp->level,
rnp->grplo, rnp->grphi, "EndWait");
trace_rcu_future_gp(rnp, rdp, c, "EndWait");
smp_mb(); /* Ensure that CB invocation happens after GP end. */
}
@@ -2375,9 +2292,8 @@ static int rcu_nocb_needs_gp(struct rcu_state *rsp)
return 0;
}
static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
{
return 0;
}
static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq)