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Subject[021/105] staging: hv: use sync_bitops when interacting with the hypervisor
2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Olaf Hering <olaf@aepfle.de>

commit 22356585712d1ff08fbfed152edd8b386873b238 upstream.

Locking is required when tweaking bits located in a shared page, use the
sync_ version of bitops. Without this change vmbus_on_event() will miss
events and as a result, vmbus_isr() will not schedule the receive tasklet.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Haiyang Zhang <haiyangz@microsoft.com>
Acked-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/staging/hv/channel.c | 8 ++++----
drivers/staging/hv/connection.c | 4 ++--
drivers/staging/hv/vmbus_drv.c | 2 +-
drivers/staging/hv/vmbus_private.h | 1 +
4 files changed, 8 insertions(+), 7 deletions(-)
--- a/drivers/staging/hv/channel.c
+++ b/drivers/staging/hv/channel.c
@@ -76,14 +76,14 @@ static void vmbus_setevent(struct vmbus_

if (channel->offermsg.monitor_allocated) {
/* Each u32 represents 32 channels */
- set_bit(channel->offermsg.child_relid & 31,
+ sync_set_bit(channel->offermsg.child_relid & 31,
(unsigned long *) gVmbusConnection.SendInterruptPage +
(channel->offermsg.child_relid >> 5));

monitorpage = gVmbusConnection.MonitorPages;
monitorpage++; /* Get the child to parent monitor page */

- set_bit(channel->monitor_bit,
+ sync_set_bit(channel->monitor_bit,
(unsigned long *)&monitorpage->trigger_group
[channel->monitor_grp].pending);

@@ -99,7 +99,7 @@ static void VmbusChannelClearEvent(struc

if (Channel->offermsg.monitor_allocated) {
/* Each u32 represents 32 channels */
- clear_bit(Channel->offermsg.child_relid & 31,
+ sync_clear_bit(Channel->offermsg.child_relid & 31,
(unsigned long *)gVmbusConnection.SendInterruptPage +
(Channel->offermsg.child_relid >> 5));

@@ -107,7 +107,7 @@ static void VmbusChannelClearEvent(struc
(struct hv_monitor_page *)gVmbusConnection.MonitorPages;
monitorPage++; /* Get the child to parent monitor page */

- clear_bit(Channel->monitor_bit,
+ sync_clear_bit(Channel->monitor_bit,
(unsigned long *)&monitorPage->trigger_group
[Channel->monitor_grp].Pending);
}
--- a/drivers/staging/hv/connection.c
+++ b/drivers/staging/hv/connection.c
@@ -281,7 +281,7 @@ void VmbusOnEvents(void)
for (dword = 0; dword < maxdword; dword++) {
if (recvInterruptPage[dword]) {
for (bit = 0; bit < 32; bit++) {
- if (test_and_clear_bit(bit, (unsigned long *)&recvInterruptPage[dword])) {
+ if (sync_test_and_clear_bit(bit, (unsigned long *)&recvInterruptPage[dword])) {
relid = (dword << 5) + bit;
DPRINT_DBG(VMBUS, "event detected for relid - %d", relid);

@@ -320,7 +320,7 @@ int VmbusPostMessage(void *buffer, size_
int VmbusSetEvent(u32 childRelId)
{
/* Each u32 represents 32 channels */
- set_bit(childRelId & 31,
+ sync_set_bit(childRelId & 31,
(unsigned long *)gVmbusConnection.SendInterruptPage +
(childRelId >> 5));

--- a/drivers/staging/hv/vmbus_drv.c
+++ b/drivers/staging/hv/vmbus_drv.c
@@ -291,7 +291,7 @@ static int vmbus_on_isr(struct hv_driver
event = (union hv_synic_event_flags *)page_addr + VMBUS_MESSAGE_SINT;

/* Since we are a child, we only need to check bit 0 */
- if (test_and_clear_bit(0, (unsigned long *) &event->flags32[0])) {
+ if (sync_test_and_clear_bit(0, (unsigned long *) &event->flags32[0])) {
DPRINT_DBG(VMBUS, "received event %d", event->flags32[0]);
ret |= 0x2;
}
--- a/drivers/staging/hv/vmbus_private.h
+++ b/drivers/staging/hv/vmbus_private.h
@@ -31,6 +31,7 @@
#include "channel_mgmt.h"
#include "ring_buffer.h"
#include <linux/list.h>
+#include <asm/sync_bitops.h>


/*



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