> -----Original Message-----
> From: Jason Wang [mailto:jasow...@redhat.com]
> Sent: Monday, February 2, 2015 17:41 PM
> To: Dexuan Cui
> Cc: gre...@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev-
> de...@linuxdriverproject.org; o...@aepfle.de; a...@canonical.com; KY
> Srinivasan; vkuzn...@redhat.com; Haiyang Zhang
> Subject: Re: [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 <de...@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.
I'm not sure about the details either.
And it may be pretty host-specific, e.g., I can only get the error code on
Hyper-V 2008 R2, but can't get it on 2012 R2.
> Reviewed-by: Jason Wang <jasow...@redhat.com>
Thanks!
> >
> > 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" <k...@microsoft.com>
> > Signed-off-by: Dexuan Cui <de...@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
> >
