On Wed, Apr 12, 2017 at 11:13:41PM +0530, Sumit Semwal wrote:
> From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>
> [ Upstream commit 4d63763296ab7865a98bc29cc7d77145815ef89f ]
>
> We use messagecount only once in vmbus_establish_gpadl() to check if
> it is safe to iterate through the submsglist. We can just initialize
> the list header in all cases in create_gpadl_header() instead.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> ---
> drivers/hv/channel.c | 38 ++++++++++++++++----------------------
> 1 file changed, 16 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
> index 1ef37c7..fb1e3df 100644
> --- a/drivers/hv/channel.c
> +++ b/drivers/hv/channel.c
> @@ -223,8 +223,7 @@ EXPORT_SYMBOL_GPL(vmbus_open);
> * create_gpadl_header - Creates a gpadl for the specified buffer
> */
> static int create_gpadl_header(void *kbuffer, u32 size,
> - struct vmbus_channel_msginfo **msginfo,
> - u32 *messagecount)
> + struct vmbus_channel_msginfo **msginfo)
> {
> int i;
> int pagecount;
> @@ -268,7 +267,6 @@ static int create_gpadl_header(void *kbuffer, u32 size,
> gpadl_header->range[0].pfn_array[i] = slow_virt_to_phys(
> kbuffer + PAGE_SIZE * i) >> PAGE_SHIFT;
> *msginfo = msgheader;
> - *messagecount = 1;
>
> pfnsum = pfncount;
> pfnleft = pagecount - pfncount;
> @@ -308,7 +306,6 @@ static int create_gpadl_header(void *kbuffer, u32 size,
> }
>
> msgbody->msgsize = msgsize;
> - (*messagecount)++;
> gpadl_body =
> (struct vmbus_channel_gpadl_body *)msgbody->msg;
>
> @@ -337,6 +334,8 @@ static int create_gpadl_header(void *kbuffer, u32 size,
> msgheader = kzalloc(msgsize, GFP_KERNEL);
> if (msgheader == NULL)
> goto nomem;
> +
> + INIT_LIST_HEAD(&msgheader->submsglist);
> msgheader->msgsize = msgsize;
>
> gpadl_header = (struct vmbus_channel_gpadl_header *)
> @@ -351,7 +350,6 @@ static int create_gpadl_header(void *kbuffer, u32 size,
> kbuffer + PAGE_SIZE * i) >> PAGE_SHIFT;
>
> *msginfo = msgheader;
> - *messagecount = 1;
> }
>
> return 0;
> @@ -376,7 +374,6 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
> struct vmbus_channel_gpadl_body *gpadl_body;
> struct vmbus_channel_msginfo *msginfo = NULL;
> struct vmbus_channel_msginfo *submsginfo;
> - u32 msgcount;
> struct list_head *curr;
> u32 next_gpadl_handle;
> unsigned long flags;
> @@ -385,7 +382,7 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
> next_gpadl_handle =
> (atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
>
> - ret = create_gpadl_header(kbuffer, size, &msginfo, &msgcount);
> + ret = create_gpadl_header(kbuffer, size, &msginfo);
> if (ret)
> return ret;
>
> @@ -408,24 +405,21 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
> if (ret != 0)
> goto cleanup;
>
> - if (msgcount > 1) {
> - list_for_each(curr, &msginfo->submsglist) {
> + list_for_each(curr, &msginfo->submsglist) {
> + submsginfo = (struct vmbus_channel_msginfo *)curr;
> + gpadl_body =
> + (struct vmbus_channel_gpadl_body *)submsginfo->msg;
>
> - submsginfo = (struct vmbus_channel_msginfo *)curr;
> - gpadl_body =
> - (struct vmbus_channel_gpadl_body *)submsginfo->msg;
> + gpadl_body->header.msgtype =
> + CHANNELMSG_GPADL_BODY;
> + gpadl_body->gpadl = next_gpadl_handle;
>
> - gpadl_body->header.msgtype =
> - CHANNELMSG_GPADL_BODY;
> - gpadl_body->gpadl = next_gpadl_handle;
> + ret = vmbus_post_msg(gpadl_body,
> + submsginfo->msgsize -
> + sizeof(*submsginfo));
> + if (ret != 0)
> + goto cleanup;
>
> - ret = vmbus_post_msg(gpadl_body,
> - submsginfo->msgsize -
> - sizeof(*submsginfo));
> - if (ret != 0)
> - goto cleanup;
> -
> - }
> }
> wait_for_completion(&msginfo->waitevent);
>
Why should this go into a stable kernel? What does it fix?
thanks,
greg k-h