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SubjectRe: [PATCH 4/5] hv: kvp: use wrappers to propaigate state
On Tue, Sep 15, 2015 at 05:37:53PM -0700, K. Y. Srinivasan wrote:
> From: Olaf Hering <olaf@aepfle.de>
>
> The "state" is used by several threads of execution.
> Propagate the state to make changes visible. Also propagate context
> change in kvp_on_msg.
>
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> ---
> drivers/hv/hv_kvp.c | 39 +++++++++++++++++++++------------------
> 1 files changed, 21 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
> index 74c38a9..778d353 100644
> --- a/drivers/hv/hv_kvp.c
> +++ b/drivers/hv/hv_kvp.c
> @@ -61,7 +61,7 @@
> */
>
> static struct {
> - int state; /* hvutil_device_state */
> + enum hvutil_device_state state;
> int recv_len; /* number of bytes received. */
> struct hv_kvp_msg *kvp_msg; /* current message */
> struct vmbus_channel *recv_channel; /* chn we got the request */
> @@ -74,6 +74,9 @@ static struct {
> */
> static int dm_reg_value;
>
> +#define kvp_get_state() hvutil_device_get_state(&kvp_transaction.state)
> +#define kvp_set_state(s) hvutil_device_set_state(&kvp_transaction.state, s)
> +
> static void kvp_send_key(struct work_struct *dummy);
>
>
> @@ -122,8 +125,8 @@ static void kvp_timeout_func(struct work_struct *dummy)
> kvp_respond_to_host(NULL, HV_E_FAIL);
>
> /* Transaction is finished, reset the state. */
> - if (kvp_transaction.state > HVUTIL_READY)
> - kvp_transaction.state = HVUTIL_READY;
> + if (kvp_get_state() > HVUTIL_READY)
> + kvp_set_state(HVUTIL_READY);
>

And what if the state changed the line after this? Oops, your code is
hosed. See, you need a lock, do this correctly.

greg k-h


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