# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1273143595 -3600
# Node ID ccae861f52f7f25aa2ab404a6110831402845dac
# Parent 924f54145fda26df64bf6f57010793893b29866f
Reduce '0' debug key's global impact
On large systems, dumping state may cause time management to get
stalled for so long a period that it wouldn't recover. Therefore add
a tasklet-based alternative mechanism to handle Dom0 state dumps.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
xen/common/keyhandler.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 51 insertions(+)
diff -r 924f54145fda -r ccae861f52f7 xen/common/keyhandler.c
--- a/xen/common/keyhandler.c Thu May 06 11:52:22 2010 +0100
+++ b/xen/common/keyhandler.c Thu May 06 11:59:55 2010 +0100
@@ -19,6 +19,7 @@
static struct keyhandler *key_table[256];
static unsigned char keypress_key;
+static bool_t alt_key_handling;
char keyhandler_scratch[1024];
@@ -115,6 +116,26 @@ static struct keyhandler dump_registers_
.desc = "dump registers"
};
+static DECLARE_TASKLET(dump_dom0_tasklet, NULL, 0);
+
+static void dump_dom0_action(unsigned long arg)
+{
+ struct vcpu *v = (void *)arg;
+
+ for ( ; ; )
+ {
+ vcpu_show_execution_state(v);
+ if ( (v = v->next_in_list) == NULL )
+ break;
+ if ( softirq_pending(smp_processor_id()) )
+ {
+ dump_dom0_tasklet.data = (unsigned long)v;
+ tasklet_schedule_on_cpu(&dump_dom0_tasklet, v->processor);
+ break;
+ }
+ }
+}
+
static void dump_dom0_registers(unsigned char key)
{
struct vcpu *v;
@@ -125,7 +146,17 @@ static void dump_dom0_registers(unsigned
printk("'%c' pressed -> dumping Dom0's registers\n", key);
for_each_vcpu ( dom0, v )
+ {
+ if ( alt_key_handling && softirq_pending(smp_processor_id()) )
+ {
+ tasklet_kill(&dump_dom0_tasklet);
+ tasklet_init(&dump_dom0_tasklet, dump_dom0_action,
+ (unsigned long)v);
+ tasklet_schedule_on_cpu(&dump_dom0_tasklet, v->processor);
+ return;
+ }
vcpu_show_execution_state(v);
+ }
}
static struct keyhandler dump_dom0_registers_keyhandler = {
@@ -425,8 +456,28 @@ static struct keyhandler do_debug_key_ke
.desc = "trap to xendbg"
};
+static void do_toggle_alt_key(unsigned char key, struct cpu_user_regs *regs)
+{
+ alt_key_handling = !alt_key_handling;
+ printk("'%c' pressed -> using %s key handling\n", key,
+ alt_key_handling ? "alternative" : "normal");
+}
+
+static struct keyhandler toggle_alt_keyhandler = {
+ .irq_callback = 1,
+ .u.irq_fn = do_toggle_alt_key,
+ .desc = "toggle alternative key handling"
+};
+
void __init initialize_keytable(void)
{
+ if ( num_present_cpus() > 16 )
+ {
+ alt_key_handling = 1;
+ printk(XENLOG_INFO "Defaulting to alternative key handling; "
+ "send 'A' to switch to normal mode.\n");
+ }
+ register_keyhandler('A', &toggle_alt_keyhandler);
register_keyhandler('d', &dump_registers_keyhandler);
register_keyhandler('h', &show_handlers_keyhandler);
register_keyhandler('q', &dump_domains_keyhandler);
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