[Xen-changelog] [xen-unstable] Do not deadlock in scheduler when sending VIRQ_CON_RING.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1236349707 0
# Node ID 3fd8f9b349413c5a04d0e3f93e43463f1021c9dc
# Parent  cff29d694a8905e94dfe7506ca1e3482c2c8a76b
Do not deadlock in scheduler when sending VIRQ_CON_RING.
Instead defer the virq notification to tasklet context.

Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
 xen/drivers/char/console.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff -r cff29d694a89 -r 3fd8f9b34941 xen/drivers/char/console.c
--- a/xen/drivers/char/console.c        Thu Mar 05 17:50:05 2009 +0000
+++ b/xen/drivers/char/console.c        Fri Mar 06 14:28:27 2009 +0000
@@ -315,6 +315,12 @@ static void serial_rx(char c, struct cpu
     __serial_rx(c, regs);
 }
 
+static void notify_dom0_con_ring(unsigned long unused)
+{
+    send_guest_global_virq(dom0, VIRQ_CON_RING);
+}
+static DECLARE_TASKLET(notify_dom0_con_ring_tasklet, notify_dom0_con_ring, 0);
+
 static long guest_console_write(XEN_GUEST_HANDLE(char) buffer, int count)
 {
     char kbuf[128], *kptr;
@@ -348,7 +354,7 @@ static long guest_console_write(XEN_GUES
         {
             for ( kptr = kbuf; *kptr != '\0'; kptr++ )
                 putchar_console_ring(*kptr);
-            send_guest_global_virq(dom0, VIRQ_CON_RING);
+            tasklet_schedule(&notify_dom0_con_ring_tasklet);
         }
 
         spin_unlock_irq(&console_lock);
@@ -426,7 +432,7 @@ static void __putstr(const char *str)
     while ( (c = *str++) != '\0' )
         putchar_console_ring(c);
 
-    send_guest_global_virq(dom0, VIRQ_CON_RING);
+    tasklet_schedule(&notify_dom0_con_ring_tasklet);
 }
 
 static int printk_prefix_check(char *p, char **pp)

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