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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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