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SubjectRe: [PATCH v2 2/3] hv: vmbus_post_msg: retry the hypercall on some transient errors


On Mon, Feb 2, 2015 at 12:36 PM, Dexuan Cui <decui@microsoft.com> wrote:
> I got HV_STATUS_INVALID_CONNECTION_ID on Hyper-V 2008 R2 when keeping
> running
> "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe
> hv_utils"
> in a Linux guest. Looks the host has some kind of throttling
> mechanism if
> some kinds of hypercalls are sent too frequently.

Better to clarify this kind of throttling. Looks like it only affects
HVCALL_POST_MESSAGE. Other looks good.

Reviewed-by: Jason Wang <jasowang@redhat.com>
>
> Without the patch, the driver can occasionally fail to load.
>
> Also let's retry HV_STATUS_INSUFFICIENT_MEMORY, though we didn't get
> it
> before.
>
> Removed 'case -ENOMEM', since the hypervisor doesn't return this.
>
> CC: "K. Y. Srinivasan" <kys@microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
>
> v2:
> updated the subject and changelog
> on HV_STATUS_INVALID_CONNECTION_ID: ret = -EAGAIN;
> added HV_STATUS_INSUFFICIENT_MEMORY
> removed unreachable -ENOMEM
> changed the delay from 100ms to 1000ms
>
> arch/x86/include/uapi/asm/hyperv.h | 2 ++
> drivers/hv/connection.c | 11 +++++++++--
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/uapi/asm/hyperv.h
> b/arch/x86/include/uapi/asm/hyperv.h
> index 90c458e..ce6068d 100644
> --- a/arch/x86/include/uapi/asm/hyperv.h
> +++ b/arch/x86/include/uapi/asm/hyperv.h
> @@ -225,6 +225,8 @@
> #define HV_STATUS_INVALID_HYPERCALL_CODE 2
> #define HV_STATUS_INVALID_HYPERCALL_INPUT 3
> #define HV_STATUS_INVALID_ALIGNMENT 4
> +#define HV_STATUS_INSUFFICIENT_MEMORY 11
> +#define HV_STATUS_INVALID_CONNECTION_ID 18
> #define HV_STATUS_INSUFFICIENT_BUFFERS 19
>
> typedef struct _HV_REFERENCE_TSC_PAGE {
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index c4acd1c..af2388f 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -440,9 +440,16 @@ int vmbus_post_msg(void *buffer, size_t buflen)
> ret = hv_post_message(conn_id, 1, buffer, buflen);
>
> switch (ret) {
> + case HV_STATUS_INVALID_CONNECTION_ID:
> + /*
> + * We could get this if we send messages too
> + * frequently.
> + */
> + ret = -EAGAIN;
> + break;
> + case HV_STATUS_INSUFFICIENT_MEMORY:
> case HV_STATUS_INSUFFICIENT_BUFFERS:
> ret = -ENOMEM;
> - case -ENOMEM:
> break;
> case HV_STATUS_SUCCESS:
> return ret;
> @@ -452,7 +459,7 @@ int vmbus_post_msg(void *buffer, size_t buflen)
> }
>
> retries++;
> - msleep(100);
> + msleep(1000);
> }
> return ret;
> }
> --
> 1.9.1
>



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