[Xen-devel] [PATCH 5/8] xen/sched: use keyhandler locks when dumping data to console

[Juergen Gross <jgross@suse.com>]

Instead of using the normal locks use the keyhandler provided trylocks
with timeouts. This requires a special primitive for the scheduler
lock.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 xen/common/sched/core.c    |  7 +++++++
 xen/common/sched/cpupool.c |  4 +++-
 xen/common/sched/credit.c  | 25 ++++++++++++++++++-------
 xen/common/sched/credit2.c | 17 +++++++++++------
 xen/common/sched/null.c    | 42 +++++++++++++++++++++++++-----------------
 xen/common/sched/private.h |  1 +
 xen/common/sched/rt.c      |  7 +++++--
 7 files changed, 70 insertions(+), 33 deletions(-)

diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c
index d4e8944e0e..7b8b0fe80e 100644
--- a/xen/common/sched/core.c
+++ b/xen/common/sched/core.c
@@ -21,6 +21,7 @@
 #include <xen/domain.h>
 #include <xen/delay.h>
 #include <xen/event.h>
+#include <xen/keyhandler.h>
 #include <xen/time.h>
 #include <xen/timer.h>
 #include <xen/perfc.h>
@@ -3302,6 +3303,12 @@ void __init sched_setup_dom0_vcpus(struct domain *d)
 }
 #endif
 
+spinlock_t *keyhandler_pcpu_lock(unsigned int cpu)
+{
+    keyhandler_lock_body(spinlock_t *, pcpu_schedule_trylock(cpu),
+                         "could not get pcpu lock, cpu=%u\n", cpu);
+}
+
 #ifdef CONFIG_COMPAT
 #include "compat.c"
 #endif
diff --git a/xen/common/sched/cpupool.c b/xen/common/sched/cpupool.c
index 476916c6ea..5c181e9772 100644
--- a/xen/common/sched/cpupool.c
+++ b/xen/common/sched/cpupool.c
@@ -893,7 +893,9 @@ void dump_runq(unsigned char key)
     s_time_t         now = NOW();
     struct cpupool **c;
 
-    spin_lock(&cpupool_lock);
+    if ( !keyhandler_spin_lock(&cpupool_lock, "could not get cpupools") )
+        return;
+
     local_irq_save(flags);
 
     printk("sched_smt_power_savings: %s\n",
diff --git a/xen/common/sched/credit.c b/xen/common/sched/credit.c
index dee87e7fe2..165ff26bb8 100644
--- a/xen/common/sched/credit.c
+++ b/xen/common/sched/credit.c
@@ -2057,8 +2057,15 @@ csched_dump_pcpu(const struct scheduler *ops, int cpu)
      * - we scan through the runqueue, so we need the proper runqueue
      *   lock (the one of the runqueue of this cpu).
      */
-    spin_lock(&prv->lock);
-    lock = pcpu_schedule_lock(cpu);
+    if ( !keyhandler_spin_lock(&prv->lock, "could not get credit data") )
+        return;
+
+    lock = keyhandler_pcpu_lock(cpu);
+    if ( !lock )
+    {
+        spin_unlock(&prv->lock);
+        return;
+    }
 
     spc = CSCHED_PCPU(cpu);
     runq = &spc->runq;
@@ -2098,7 +2105,8 @@ csched_dump(const struct scheduler *ops)
     struct csched_private *prv = CSCHED_PRIV(ops);
     int loop;
 
-    spin_lock(&prv->lock);
+    if ( !keyhandler_spin_lock(&prv->lock, "could not get credit data") )
+        return;
 
     printk("info:\n"
            "\tncpus              = %u\n"
@@ -2142,12 +2150,15 @@ csched_dump(const struct scheduler *ops)
             spinlock_t *lock;
 
             svc = list_entry(iter_svc, struct csched_unit, active_unit_elem);
-            lock = unit_schedule_lock(svc->unit);
+            lock = keyhandler_pcpu_lock(svc->unit->res->master_cpu);
 
-            printk("\t%3d: ", ++loop);
-            csched_dump_unit(svc);
+            if ( lock )
+            {
+                printk("\t%3d: ", ++loop);
+                csched_dump_unit(svc);
 
-            unit_schedule_unlock(lock, svc->unit);
+                pcpu_schedule_unlock(lock, svc->unit->res->master_cpu);
+            }
         }
     }
 
diff --git a/xen/common/sched/credit2.c b/xen/common/sched/credit2.c
index e76d2ed543..28b03fe744 100644
--- a/xen/common/sched/credit2.c
+++ b/xen/common/sched/credit2.c
@@ -3655,7 +3655,8 @@ csched2_dump(const struct scheduler *ops)
      * We need the private scheduler lock as we access global
      * scheduler data and (below) the list of active domains.
      */
-    read_lock(&prv->lock);
+    if ( !keyhandler_read_lock(&prv->lock, "could not get credit2 data") )
+        return;
 
     printk("Active queues: %d\n"
            "\tdefault-weight     = %d\n",
@@ -3711,12 +3712,15 @@ csched2_dump(const struct scheduler *ops)
             struct csched2_unit * const svc = csched2_unit(unit);
             spinlock_t *lock;
 
-            lock = unit_schedule_lock(unit);
+            lock = keyhandler_pcpu_lock(unit->res->master_cpu);
 
-            printk("\t%3d: ", ++loop);
-            csched2_dump_unit(prv, svc);
+            if ( lock )
+            {
+                printk("\t%3d: ", ++loop);
+                csched2_dump_unit(prv, svc);
 
-            unit_schedule_unlock(lock, unit);
+                pcpu_schedule_unlock(lock, unit->res->master_cpu);
+            }
         }
     }
 
@@ -3727,7 +3731,8 @@ csched2_dump(const struct scheduler *ops)
         int loop = 0;
 
         /* We need the lock to scan the runqueue. */
-        spin_lock(&rqd->lock);
+        if ( !keyhandler_spin_lock(&rqd->lock, "could not get runq") )
+            continue;
 
         printk("Runqueue %d:\n", i);
 
diff --git a/xen/common/sched/null.c b/xen/common/sched/null.c
index 3b31703d7e..fe59ce17fe 100644
--- a/xen/common/sched/null.c
+++ b/xen/common/sched/null.c
@@ -28,6 +28,7 @@
  * if the scheduler is used inside a cpupool.
  */
 
+#include <xen/keyhandler.h>
 #include <xen/sched.h>
 #include <xen/softirq.h>
 #include <xen/trace.h>
@@ -982,7 +983,8 @@ static void null_dump(const struct scheduler *ops)
     struct list_head *iter;
     unsigned int loop;
 
-    spin_lock(&prv->lock);
+    if ( !keyhandler_spin_lock(&prv->lock, "could not get null data") )
+        return;
 
     printk("\tcpus_free = %*pbl\n", CPUMASK_PR(&prv->cpus_free));
 
@@ -1001,31 +1003,37 @@ static void null_dump(const struct scheduler *ops)
             struct null_unit * const nvc = null_unit(unit);
             spinlock_t *lock;
 
-            lock = unit_schedule_lock(unit);
+            lock = keyhandler_pcpu_lock(unit->res->master_cpu);
 
-            printk("\t%3d: ", ++loop);
-            dump_unit(prv, nvc);
-            printk("\n");
+            if ( lock )
+            {
+                printk("\t%3d: ", ++loop);
+                dump_unit(prv, nvc);
+                printk("\n");
 
-            unit_schedule_unlock(lock, unit);
+                pcpu_schedule_unlock(lock, unit->res->master_cpu);
+            }
         }
     }
 
     printk("Waitqueue: ");
     loop = 0;
-    spin_lock(&prv->waitq_lock);
-    list_for_each( iter, &prv->waitq )
+    if ( keyhandler_spin_lock(&prv->waitq_lock, "could not get waitq") )
     {
-        struct null_unit *nvc = list_entry(iter, struct null_unit, waitq_elem);
-
-        if ( loop++ != 0 )
-            printk(", ");
-        if ( loop % 24 == 0 )
-            printk("\n\t");
-        printk("%pdv%d", nvc->unit->domain, nvc->unit->unit_id);
+        list_for_each( iter, &prv->waitq )
+        {
+            struct null_unit *nvc = list_entry(iter, struct null_unit,
+                                               waitq_elem);
+
+            if ( loop++ != 0 )
+                printk(", ");
+            if ( loop % 24 == 0 )
+                printk("\n\t");
+            printk("%pdv%d", nvc->unit->domain, nvc->unit->unit_id);
+        }
+        printk("\n");
+        spin_unlock(&prv->waitq_lock);
     }
-    printk("\n");
-    spin_unlock(&prv->waitq_lock);
 
     spin_unlock(&prv->lock);
 }
diff --git a/xen/common/sched/private.h b/xen/common/sched/private.h
index 2a94179baa..6723f74d28 100644
--- a/xen/common/sched/private.h
+++ b/xen/common/sched/private.h
@@ -631,5 +631,6 @@ struct cpupool *cpupool_get_by_id(int poolid);
 void cpupool_put(struct cpupool *pool);
 int cpupool_add_domain(struct domain *d, int poolid);
 void cpupool_rm_domain(struct domain *d);
+spinlock_t *keyhandler_pcpu_lock(unsigned int cpu);
 
 #endif /* __XEN_SCHED_IF_H__ */
diff --git a/xen/common/sched/rt.c b/xen/common/sched/rt.c
index 16379cb2d2..d4b17e0f8b 100644
--- a/xen/common/sched/rt.c
+++ b/xen/common/sched/rt.c
@@ -354,7 +354,9 @@ rt_dump_pcpu(const struct scheduler *ops, int cpu)
     struct rt_private *prv = rt_priv(ops);
     const struct rt_unit *svc;
 
-    spin_lock(&prv->lock);
+    if ( !keyhandler_spin_lock(&prv->lock, "could not get rt data") )
+        return;
+
     printk("CPU[%02d]\n", cpu);
     /* current UNIT (nothing to say if that's the idle unit). */
     svc = rt_unit(curr_on_cpu(cpu));
@@ -373,7 +375,8 @@ rt_dump(const struct scheduler *ops)
     const struct rt_unit *svc;
     const struct rt_dom *sdom;
 
-    spin_lock(&prv->lock);
+    if ( !keyhandler_spin_lock(&prv->lock, "could not get rt data") )
+        return;
 
     if ( list_empty(&prv->sdom) )
         goto out;
-- 
2.16.4


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