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Message-ID: <DM5PR03MB2490427CEC13490584CA07D0A02D0@DM5PR03MB2490.namprd03.prod.outlook.com>
Date: Sun, 5 Mar 2017 00:03:21 +0000
From: KY Srinivasan <kys@...rosoft.com>
To: KY Srinivasan <kys@...rosoft.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
"olaf@...fle.de" <olaf@...fle.de>,
"apw@...onical.com" <apw@...onical.com>,
"vkuznets@...hat.com" <vkuznets@...hat.com>,
"jasowang@...hat.com" <jasowang@...hat.com>,
"leann.ogasawara@...onical.com" <leann.ogasawara@...onical.com>
CC: Dexuan Cui <decui@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Stephen Hemminger <sthemmin@...rosoft.com>
Subject: RE: [PATCH 1/1] Drivers: hv: util: on deinit, don't wait the release
event, if we shouldn't
> -----Original Message-----
> From: kys@...hange.microsoft.com [mailto:kys@...hange.microsoft.com]
> Sent: Monday, February 27, 2017 3:18 PM
> To: gregkh@...uxfoundation.org; linux-kernel@...r.kernel.org;
> devel@...uxdriverproject.org; olaf@...fle.de; apw@...onical.com;
> vkuznets@...hat.com; jasowang@...hat.com;
> leann.ogasawara@...onical.com
> Cc: Dexuan Cui <decui@...rosoft.com>; KY Srinivasan
> <kys@...rosoft.com>; Haiyang Zhang <haiyangz@...rosoft.com>; Stephen
> Hemminger <sthemmin@...rosoft.com>
> Subject: [PATCH 1/1] Drivers: hv: util: on deinit, don't wait the release event,
> if we shouldn't
>
> This sender failed our fraud detection&nbs
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>
> From: Dexuan Cui <decui@...rosoft.com>
>
> If the daemon is NOT running at all, when we disable the util device from
> Hyper-V Manager (or sometimes the host can rescind a util device and then
> re-offer it), we'll hang in util_remove -> hv_kvp_deinit ->
> wait_for_completion(&release_event), because this code path doesn't run:
> hvt_op_release -> ... -> kvp_on_reset -> complete(&release_event).
>
> Due to this, we even can't reboot the VM properly.
>
> The patch tracks if the dev file is opened or not, and we only need to
> wait if it's opened.
>
> Fixes: 5a66fecbf6aa ("Drivers: hv: util: kvp: Fix a rescind processing issue")
>
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
> Cc: "K. Y. Srinivasan" <kys@...rosoft.com>
> Cc: Haiyang Zhang <haiyangz@...rosoft.com>
> Cc: Stephen Hemminger <sthemmin@...rosoft.com>
> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> ---
> drivers/hv/hv_fcopy.c | 5 ++++-
> drivers/hv/hv_kvp.c | 6 +++++-
> drivers/hv/hv_snapshot.c | 5 ++++-
> drivers/hv/hv_utils_transport.c | 2 ++
> drivers/hv/hv_utils_transport.h | 1 +
> 5 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
> index 9aee601..545cf43 100644
> --- a/drivers/hv/hv_fcopy.c
> +++ b/drivers/hv/hv_fcopy.c
> @@ -358,8 +358,11 @@ int hv_fcopy_init(struct hv_util_service *srv)
>
> void hv_fcopy_deinit(void)
> {
> + bool wait = hvt->dev_opened;
> +
> fcopy_transaction.state = HVUTIL_DEVICE_DYING;
> cancel_delayed_work_sync(&fcopy_timeout_work);
> hvutil_transport_destroy(hvt);
> - wait_for_completion(&release_event);
> + if (wait)
> + wait_for_completion(&release_event);
> }
> diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
> index de26371..15c7873 100644
> --- a/drivers/hv/hv_kvp.c
> +++ b/drivers/hv/hv_kvp.c
> @@ -742,10 +742,14 @@ static void kvp_on_reset(void)
>
> void hv_kvp_deinit(void)
> {
> + bool wait = hvt->dev_opened;
> +
> kvp_transaction.state = HVUTIL_DEVICE_DYING;
> cancel_delayed_work_sync(&kvp_host_handshake_work);
> cancel_delayed_work_sync(&kvp_timeout_work);
> cancel_work_sync(&kvp_sendkey_work);
> hvutil_transport_destroy(hvt);
> - wait_for_completion(&release_event);
> +
> + if (wait)
> + wait_for_completion(&release_event);
> }
> diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
> index bcc03f0..3847f19 100644
> --- a/drivers/hv/hv_snapshot.c
> +++ b/drivers/hv/hv_snapshot.c
> @@ -396,9 +396,12 @@ static void vss_on_reset(void)
>
> void hv_vss_deinit(void)
> {
> + bool wait = hvt->dev_opened;
> +
> vss_transaction.state = HVUTIL_DEVICE_DYING;
> cancel_delayed_work_sync(&vss_timeout_work);
> cancel_work_sync(&vss_handle_request_work);
> hvutil_transport_destroy(hvt);
> - wait_for_completion(&release_event);
> + if (wait)
> + wait_for_completion(&release_event);
> }
> diff --git a/drivers/hv/hv_utils_transport.c b/drivers/hv/hv_utils_transport.c
> index c235a95..05e0648 100644
> --- a/drivers/hv/hv_utils_transport.c
> +++ b/drivers/hv/hv_utils_transport.c
> @@ -153,6 +153,7 @@ static int hvt_op_open(struct inode *inode, struct file
> *file)
>
> if (issue_reset)
> hvt_reset(hvt);
> + hvt->dev_opened = (hvt->mode == HVUTIL_TRANSPORT_CHARDEV)
> && !ret;
>
> mutex_unlock(&hvt->lock);
>
> @@ -182,6 +183,7 @@ static int hvt_op_release(struct inode *inode, struct
> file *file)
> * connects back.
> */
> hvt_reset(hvt);
> + hvt->dev_opened = false;
> mutex_unlock(&hvt->lock);
>
> if (mode_old == HVUTIL_TRANSPORT_DESTROY)
> diff --git a/drivers/hv/hv_utils_transport.h b/drivers/hv/hv_utils_transport.h
> index d98f522..9871283 100644
> --- a/drivers/hv/hv_utils_transport.h
> +++ b/drivers/hv/hv_utils_transport.h
> @@ -32,6 +32,7 @@ struct hvutil_transport {
> int mode; /* hvutil_transport_mode */
> struct file_operations fops; /* file operations */
> struct miscdevice mdev; /* misc device */
> + bool dev_opened; /* Is the device opened? */
> struct cb_id cn_id; /* CN_*_IDX/CN_*_VAL */
> struct list_head list; /* hvt_list */
> int (*on_msg)(void *, int); /* callback on new user message */
> --
> 1.7.1
Greg,
Please drop this patch.
K. Y
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