# HG changeset patch
# Parent 3b563b2c79f991f226bd383d40402d96ddf9a168
x86/irq: Prevent call to xfree in dump_irqs while in an irq context.

Because of c/s 24707:96987c324a4f, dump_irqs() can now be called in an irq
context when a bug condition is encountered.  If this is the case, ignore the
call to xsm_show_irq_ssid() and the subsequent call to xfree.

This prevents an assertion failure in xfree(), and should allow all the debug
information to be dumped, before failing with a BUG() because of the underlying
race condition we are attempting to reproduce.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

diff -r 3b563b2c79f9 xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -2039,7 +2039,7 @@ static void dump_irqs(unsigned char key)
     struct domain *d;
     const struct pirq *info;
     unsigned long flags;
-    char *ssid;
+    char *ssid = NULL;
 
     printk("Guest interrupt information:\n");
 
@@ -2051,7 +2051,8 @@ static void dump_irqs(unsigned char key)
         if ( !irq_desc_initialized(desc) || desc->handler == &no_irq_type )
             continue;
 
-        ssid = xsm_show_irq_sid(irq);
+        if ( ! in_irq() )
+            ssid = xsm_show_irq_sid(irq);
 
         spin_lock_irqsave(&desc->lock, flags);
 
@@ -2098,7 +2099,8 @@ static void dump_irqs(unsigned char key)
 
         spin_unlock_irqrestore(&desc->lock, flags);
 
-        xfree(ssid);
+        if ( ! in_irq() )
+            xfree(ssid);
     }
 
     dump_ioapic_irq_info();