Replace process_pending_timers() with process_pending_softirqs().

This ensures that any critical softirqs are handled in a timely manner
(e.g., TIME_CALIBRATE_SOFTIRQ) while still avoiding being preempted by
the scheduler (by SCHEDULE_SOFTIRQ), which is the reason for avoiding
use of do_softirq() directly.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index 35c272358264843035e8c5014f4ee8fb9a852c08..45030ba40200db145b0ec8d0461dd2aa4b21974d 100644 (file)
--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -230,7 +230,7 @@ static void acpi_processor_idle(void)
 
     sched_tick_suspend();
     /* sched_tick_suspend() can raise TIMER_SOFTIRQ. Process it now. */
-    process_pending_timers();
+    process_pending_softirqs();
 
     /*
      * Interrupts must be disabled during bus mastering calculations and

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index c4b4a66921385ede51132b16c3b816e65ec1869d..8f69aab2a94b51325ce2f19965b027e6a66d6ce3 100644 (file)
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -924,7 +924,7 @@ int __init construct_dom0(
             ((unsigned int *)vphysmap_start)[pfn] = mfn;
         set_gpfn_from_mfn(mfn, pfn);
         if (!(pfn & 0xfffff))
-            process_pending_timers();
+            process_pending_softirqs();
     }
     si->first_p2m_pfn = pfn;
     si->nr_p2m_frames = d->tot_pages - count;
@@ -945,7 +945,7 @@ int __init construct_dom0(
             ++alloc_epfn;
 #endif
             if (!(pfn & 0xfffff))
-                process_pending_timers();
+                process_pending_softirqs();
         }
     }
     BUG_ON(pfn != d->tot_pages);
@@ -967,7 +967,7 @@ int __init construct_dom0(
 #undef pfn
             page++; pfn++;
             if (!(pfn & 0xfffff))
-                process_pending_timers();
+                process_pending_softirqs();
         }
     }
 

diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 5bf5461ce8f45058ab8f4aa4d94d285c230a3877..5220d5173a1c230b580fac99af3e92fbe01514bc 100644 (file)
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -1327,7 +1327,7 @@ void __cpu_die(unsigned int cpu)
                }
                mdelay(100);
                mb();
-               process_pending_timers();
+               process_pending_softirqs();
                if ((++i % 10) == 0)
                        printk(KERN_ERR "CPU %u still not dead...\n", cpu);
        }
@@ -1547,7 +1547,7 @@ int __devinit __cpu_up(unsigned int cpu)
        cpu_set(cpu, smp_commenced_mask);
        while (!cpu_isset(cpu, cpu_online_map)) {
                mb();
-               process_pending_timers();
+               process_pending_softirqs();
        }
 
        cpufreq_add_cpu(cpu);

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 19a7bd24d136a3b66b2febda8e06d1da4cbf38fc..7139c3d39b796832a8a3bb52d0f49cfb442d2bdf 100644 (file)
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -893,7 +893,7 @@ void __init scrub_heap_pages(void)
 
     for ( mfn = first_valid_mfn; mfn < max_page; mfn++ )
     {
-        process_pending_timers();
+        process_pending_softirqs();
 
         pg = mfn_to_page(mfn);
 

diff --git a/xen/common/softirq.c b/xen/common/softirq.c
index ecf33793889fdfa01818636afd34fdaf3c9aaed2..7b04f36f2d45ba1d45adfa3b7c4802d60963b0bc 100644 (file)
--- a/xen/common/softirq.c
+++ b/xen/common/softirq.c
@@ -22,7 +22,7 @@ irq_cpustat_t irq_stat[NR_CPUS];
 
 static softirq_handler softirq_handlers[NR_SOFTIRQS];
 
-asmlinkage void do_softirq(void)
+static void __do_softirq(unsigned long ignore_mask)
 {
     unsigned int i, cpu;
     unsigned long pending;
@@ -38,7 +38,7 @@ asmlinkage void do_softirq(void)
         if ( rcu_pending(cpu) )
             rcu_check_callbacks(cpu);
 
-        if ( (pending = softirq_pending(cpu)) == 0 )
+        if ( (pending = (softirq_pending(cpu) & ~ignore_mask)) == 0 )
             break;
 
         i = find_first_set_bit(pending);
@@ -47,6 +47,18 @@ asmlinkage void do_softirq(void)
     }
 }
 
+void process_pending_softirqs(void)
+{
+    ASSERT(!in_irq() && local_irq_is_enabled());
+    /* Do not enter scheduler as it can preempt the calling context. */
+    __do_softirq(1ul<<SCHEDULE_SOFTIRQ);
+}
+
+asmlinkage void do_softirq(void)
+{
+    __do_softirq(0);
+}
+
 void open_softirq(int nr, softirq_handler handler)
 {
     ASSERT(nr < NR_SOFTIRQS);

diff --git a/xen/common/timer.c b/xen/common/timer.c
index 5cf61118d54c17bacf57d37b234300586683074b..7a84bac671fe2e8dbf75858f42eae0debefe9256 100644 (file)
--- a/xen/common/timer.c
+++ b/xen/common/timer.c
@@ -467,15 +467,6 @@ static void timer_softirq_action(void)
     spin_unlock_irq(&ts->lock);
 }
 
-
-void process_pending_timers(void)
-{
-    unsigned int cpu = smp_processor_id();
-    ASSERT(!in_irq() && local_irq_is_enabled());
-    if ( test_and_clear_bit(TIMER_SOFTIRQ, &softirq_pending(cpu)) )
-        timer_softirq_action();
-}
-
 s_time_t align_timer(s_time_t firsttick, uint64_t period)
 {
     if ( !period )

diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 97e38ad48519d41d7ee1fa98c15af2d71649662e..b1ed507f18e254a0575ff81e528060464c6cefd8 100644 (file)
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -650,7 +650,7 @@ void __init console_endboot(void)
             printk("%d... ", 3-i);
             for ( j = 0; j < 100; j++ )
             {
-                process_pending_timers();
+                process_pending_softirqs();
                 mdelay(10);
             }
         }

diff --git a/xen/include/xen/softirq.h b/xen/include/xen/softirq.h
index 5d5661fd43e65d29f0d4ac131c3eabd61f539b4f..b02c8e2509069a8a5b9f6af72321162c433c4e47 100644 (file)
--- a/xen/include/xen/softirq.h
+++ b/xen/include/xen/softirq.h
@@ -33,6 +33,13 @@ void cpumask_raise_softirq(cpumask_t mask, unsigned int nr);
 void cpu_raise_softirq(unsigned int cpu, unsigned int nr);
 void raise_softirq(unsigned int nr);
 
+/*
+ * Process pending softirqs on this CPU. This should be called periodically
+ * when performing work that prevents softirqs from running in a timely manner.
+ * Use this instead of do_softirq() when you do not want to be preempted.
+ */
+void process_pending_softirqs(void);
+
 /*
  * TASKLETS -- dynamically-allocatable tasks run in softirq context
  * on at most one CPU at a time.

diff --git a/xen/include/xen/timer.h b/xen/include/xen/timer.h
index 1994eff00fee7160a961729cf4f49b3d518d62c1..f5340d07b75d46f7e0d283bd863a74598a70f528 100644 (file)
--- a/xen/include/xen/timer.h
+++ b/xen/include/xen/timer.h
@@ -102,12 +102,6 @@ extern void migrate_timer(struct timer *timer, unsigned int new_cpu);
  */
 extern void kill_timer(struct timer *timer);
 
-/*
- * Process pending timers on this CPU. This should be called periodically
- * when performing work that prevents softirqs from running in a timely manner.
- */
-extern void process_pending_timers(void);
-
 /*
  * Bootstrap initialisation. Must be called before any other timer function.
  */