[Xen-changelog] [xen master] remove on-stack cpumask from stop_machine_run()

[patchbot@xxxxxxx]

commit 07d650f6699f06687732ec35eb539609cd70c7d9
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Mon Jun 3 17:17:51 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jun 3 17:17:51 2019 +0200

    remove on-stack cpumask from stop_machine_run()
    
    The "allbutself" cpumask in stop_machine_run() is not needed. Instead
    of allocating it on the stack it can easily be avoided.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/common/stop_machine.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/xen/common/stop_machine.c b/xen/common/stop_machine.c
index ce6f5624c4..681b40906d 100644
--- a/xen/common/stop_machine.c
+++ b/xen/common/stop_machine.c
@@ -69,8 +69,8 @@ static void stopmachine_wait_state(void)
 
 int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
 {
-    cpumask_t allbutself;
     unsigned int i, nr_cpus;
+    unsigned int this = smp_processor_id();
     int ret;
 
     BUG_ON(!local_irq_is_enabled());
@@ -79,9 +79,9 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned 
int cpu)
     if ( !get_cpu_maps() )
         return -EBUSY;
 
-    cpumask_andnot(&allbutself, &cpu_online_map,
-                   cpumask_of(smp_processor_id()));
-    nr_cpus = cpumask_weight(&allbutself);
+    nr_cpus = num_online_cpus();
+    if ( cpu_online(this) )
+        nr_cpus--;
 
     /* Must not spin here as the holder will expect us to be descheduled. */
     if ( !spin_trylock(&stopmachine_lock) )
@@ -100,8 +100,9 @@ int stop_machine_run(int (*fn)(void *), void *data, 
unsigned int cpu)
 
     smp_wmb();
 
-    for_each_cpu ( i, &allbutself )
-        tasklet_schedule_on_cpu(&per_cpu(stopmachine_tasklet, i), i);
+    for_each_online_cpu ( i )
+        if ( i != this )
+            tasklet_schedule_on_cpu(&per_cpu(stopmachine_tasklet, i), i);
 
     stopmachine_set_state(STOPMACHINE_PREPARE);
     stopmachine_wait_state();
@@ -112,7 +113,7 @@ int stop_machine_run(int (*fn)(void *), void *data, 
unsigned int cpu)
     spin_debug_disable();
 
     stopmachine_set_state(STOPMACHINE_INVOKE);
-    if ( (cpu == smp_processor_id()) || (cpu == NR_CPUS) )
+    if ( (cpu == this) || (cpu == NR_CPUS) )
     {
         ret = (*fn)(data);
         if ( ret )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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