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Subject[16/74] staging: hv: use sync_bitops when interacting with the hypervisor
2.6.32-longterm 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.

[Backported to 2.6.32 stable kernel by Haiyang Zhang <haiyangz@microsoft.com>]

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 | 6 ++++--
drivers/staging/hv/Vmbus.c | 2 +-
drivers/staging/hv/VmbusPrivate.h | 1 +
4 files changed, 10 insertions(+), 7 deletions(-)

--- a/drivers/staging/hv/Channel.c
+++ b/drivers/staging/hv/Channel.c
@@ -75,14 +75,14 @@ static void VmbusChannelSetEvent(struct

if (Channel->OfferMsg.MonitorAllocated) {
/* Each u32 represents 32 channels */
- set_bit(Channel->OfferMsg.ChildRelId & 31,
+ sync_set_bit(Channel->OfferMsg.ChildRelId & 31,
(unsigned long *) gVmbusConnection.SendInterruptPage +
(Channel->OfferMsg.ChildRelId >> 5));

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

- set_bit(Channel->MonitorBit,
+ sync_set_bit(Channel->MonitorBit,
(unsigned long *)&monitorPage->TriggerGroup
[Channel->MonitorGroup].Pending);

@@ -102,7 +102,7 @@ static void VmbusChannelClearEvent(struc

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

@@ -110,7 +110,7 @@ static void VmbusChannelClearEvent(struc
(struct hv_monitor_page *)gVmbusConnection.MonitorPages;
monitorPage++; /* Get the child to parent monitor page */

- clear_bit(Channel->MonitorBit,
+ sync_clear_bit(Channel->MonitorBit,
(unsigned long *)&monitorPage->TriggerGroup
[Channel->MonitorGroup].Pending);
}
--- a/drivers/staging/hv/Connection.c
+++ b/drivers/staging/hv/Connection.c
@@ -284,7 +284,9 @@ 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);

@@ -329,7 +331,7 @@ int VmbusSetEvent(u32 childRelId)
DPRINT_ENTER(VMBUS);

/* 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.c
+++ b/drivers/staging/hv/Vmbus.c
@@ -254,7 +254,7 @@ static int VmbusOnISR(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/VmbusPrivate.h
+++ b/drivers/staging/hv/VmbusPrivate.h
@@ -32,6 +32,7 @@
#include "ChannelInterface.h"
#include "RingBuffer.h"
#include <linux/list.h>
+#include <asm/sync_bitops.h>


/*



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