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    Subject[34-longterm 020/196] staging: hv: use sync_bitops when interacting with the hypervisor
    Date
    From: Olaf Hering <olaf@aepfle.de>

    -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
    -------------------

    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>
    Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    ---
    drivers/staging/hv/Channel.c | 8 ++++----
    drivers/staging/hv/Connection.c | 4 ++--
    drivers/staging/hv/Vmbus.c | 2 +-
    drivers/staging/hv/VmbusPrivate.h | 1 +
    4 files changed, 8 insertions(+), 7 deletions(-)

    diff --git a/drivers/staging/hv/Channel.c b/drivers/staging/hv/Channel.c
    index e69e9ee..d0b435e 100644
    --- a/drivers/staging/hv/Channel.c
    +++ b/drivers/staging/hv/Channel.c
    @@ -76,14 +76,14 @@ static void VmbusChannelSetEvent(struct vmbus_channel *Channel)

    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);

    @@ -103,7 +103,7 @@ static void VmbusChannelClearEvent(struct vmbus_channel *channel)

    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));

    @@ -111,7 +111,7 @@ static void VmbusChannelClearEvent(struct vmbus_channel *channel)
    (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);
    }
    diff --git a/drivers/staging/hv/Connection.c b/drivers/staging/hv/Connection.c
    index e0ea9cf..e39d422 100644
    --- a/drivers/staging/hv/Connection.c
    +++ b/drivers/staging/hv/Connection.c
    @@ -285,7 +285,7 @@ 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);

    @@ -330,7 +330,7 @@ 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));

    diff --git a/drivers/staging/hv/Vmbus.c b/drivers/staging/hv/Vmbus.c
    index 2f84bf7..0680868 100644
    --- a/drivers/staging/hv/Vmbus.c
    +++ b/drivers/staging/hv/Vmbus.c
    @@ -255,7 +255,7 @@ static int VmbusOnISR(struct hv_driver *drv)
    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;
    }
    diff --git a/drivers/staging/hv/VmbusPrivate.h b/drivers/staging/hv/VmbusPrivate.h
    index 05ad2c9..5a37cce 100644
    --- 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>


    /*
    --
    1.7.9.3


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