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authorLinus Torvalds <torvalds@linux-foundation.org>2021-08-14 06:31:22 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2021-08-14 06:31:22 -1000
commitba31f97d43be41ca99ab72a6131d7c226306865f (patch)
tree276e708d81eb1ab964252a7392502952d5fea76b
parenta7a4f1c0c8455657b3e19eaaffbad64a5f750c43 (diff)
parent88ca2521bd5b4e8b83743c01a2d4cb09325b51e9 (diff)
downloadlinux-ba31f97d43be41ca99ab72a6131d7c226306865f.tar.bz2
Merge tag 'for-linus-5.14-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross: "A small cleanup patch and a fix of a rare race in the Xen evtchn driver" * tag 'for-linus-5.14-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/events: Fix race in set_evtchn_to_irq xen/events: remove redundant initialization of variable irq
-rw-r--r--drivers/xen/events/events_base.c22
1 files changed, 15 insertions, 7 deletions
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index d7e361fb0548..a78704ae3618 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);
@@ -1009,7 +1017,7 @@ static void __unbind_from_irq(unsigned int irq)
int xen_bind_pirq_gsi_to_irq(unsigned gsi,
unsigned pirq, int shareable, char *name)
{
- int irq = -1;
+ int irq;
struct physdev_irq irq_op;
int ret;