linux-kernel - [021/105] staging: hv: use sync_bitops when interacting with the hypervisor

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Date:	Tue, 12 Apr 2011 07:34:10 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Olaf Hering <olaf@...fle.de>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Hank Janssen <hjanssen@...rosoft.com>
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@...fle.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@...fle.de>
Acked-by: Haiyang Zhang <haiyangz@...rosoft.com>
Acked-by: Hank Janssen <hjanssen@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.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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