author: Maximilian Heyne <mheyne@amazon.de> 2021-08-12 13:09:27 +0000
committer: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 2021-08-18 09:07:02 +0200
commit: 128e480afe783b50151124f31deb0ca0cf431d61
parent: 950429a4d346460ff95dd572f29326db60f42267
Commit Summary:
Diffstat:
1 file changed, 13 insertions, 6 deletions
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index d7e361fb0548..0e44098f3977 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -198,12 +198,12 @@ static void disable_dynirq(struct irq_data *data);
static DEFINE_PER_CPU(unsigned int, irq_epoch);
-static void clear_evtchn_to_irq_row(unsigned row)
+static void clear_evtchn_to_irq_row(int *evtchn_row)
{
unsigned col;
for (col = 0; col < EVTCHN_PER_ROW; col++)
- WRITE_ONCE(evtchn_to_irq[row][col], -1);
+ WRITE_ONCE(evtchn_row[col], -1);
}
static void clear_evtchn_to_irq_all(void)
@@ -213,7 +213,7 @@ static void clear_evtchn_to_irq_all(void)
for (row = 0; row < EVTCHN_ROW(xen_evtchn_max_channels()); row++) {
if (evtchn_to_irq[row] == NULL)
continue;
- clear_evtchn_to_irq_row(row);
+ clear_evtchn_to_irq_row(evtchn_to_irq[row]);
}
}
@@ -221,6 +221,7 @@ static int set_evtchn_to_irq(evtchn_port_t evtchn, unsigned int irq)
{
unsigned row;
unsigned col;
+ int *evtchn_row;
if (evtchn >= xen_evtchn_max_channels())
return -EINVAL;
@@ -233,11 +234,18 @@ static int set_evtchn_to_irq(evtchn_port_t evtchn, unsigned int irq)
if (irq == -1)
return 0;
- evtchn_to_irq[row] = (int *)get_zeroed_page(GFP_KERNEL);
- if (evtchn_to_irq[row] == NULL)
+ evtchn_row = (int *) __get_free_pages(GFP_KERNEL, 0);
+ if (evtchn_row == NULL)
return -ENOMEM;
- clear_evtchn_to_irq_row(row);
+ clear_evtchn_to_irq_row(evtchn_row);
+
+ /*
+ * We've prepared an empty row for the mapping. If a different
+ * thread was faster inserting it, we can drop ours.
+ */
+ if (cmpxchg(&evtchn_to_irq[row], NULL, evtchn_row) != NULL)
+ free_page((unsigned long) evtchn_row);
}
WRITE_ONCE(evtchn_to_irq[row][col], irq);