[Xen-changelog] [xen staging] x86/IRQ: relax locking in irq_guest_eoi_timer_fn()

[patchbot@xxxxxxx]

commit f6b00177c38068eb2ad1b00f62a3db4a28e18a9c
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Jun 6 11:14:00 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Jun 6 11:14:00 2019 +0200

    x86/IRQ: relax locking in irq_guest_eoi_timer_fn()
    
    This is a timer handler, so it gets entered with IRQs enabled. Therefore
    there's no need to save/restore the IRQ masking flag.
    
    Additionally the final switch()'es ACKTYPE_EOI case re-acquires the lock
    just for it to be dropped again right away. Do away with this.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/irq.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 0035174d1f..d6451a903b 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1109,9 +1109,8 @@ static void irq_guest_eoi_timer_fn(void *data)
     unsigned int irq = desc - irq_desc;
     irq_guest_action_t *action;
     cpumask_t cpu_eoi_map;
-    unsigned long flags;
 
-    spin_lock_irqsave(&desc->lock, flags);
+    spin_lock_irq(&desc->lock);
     
     if ( !(desc->status & IRQ_GUEST) )
         goto out;
@@ -1143,12 +1142,11 @@ static void irq_guest_eoi_timer_fn(void *data)
         cpumask_copy(&cpu_eoi_map, action->cpu_eoi_map);
         spin_unlock_irq(&desc->lock);
         on_selected_cpus(&cpu_eoi_map, set_eoi_ready, desc, 0);
-        spin_lock_irq(&desc->lock);
-        break;
+        return;
     }
 
  out:
-    spin_unlock_irqrestore(&desc->lock, flags);
+    spin_unlock_irq(&desc->lock);
 }
 
 static void __do_IRQ_guest(int irq)
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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