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SubjectRe: [PATCH v5 2/3] virtio-scsi: add error handling
On Sun, Feb 05, 2012 at 12:16:01PM +0100, Paolo Bonzini wrote:
> This commit adds basic error handling to the virtio-scsi
> HBA device. Task management functions are sent synchronously
> via the control virtqueue.
>
> Cc: linux-scsi <linux-scsi@vger.kernel.org>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: kvm@vger.kernel.org
> Acked-by: Pekka Enberg <penberg@kernel.org>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> v3->v4: fixed 32-bit compilation; adjusted call to virtscsi_kick_cmd
>
> v2->v3: added mempool, used GFP_NOIO instead of GFP_ATOMIC,
> formatting fixes
>
> v1->v2: use scmd_printk
>
> drivers/scsi/virtio_scsi.c | 73 +++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 72 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 3f87ae0..68104cd 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -29,6 +29,7 @@
> /* Command queue element */
> struct virtio_scsi_cmd {
> struct scsi_cmnd *sc;
> + struct completion *comp;
> union {
> struct virtio_scsi_cmd_req cmd;
> struct virtio_scsi_ctrl_tmf_req tmf;
> @@ -168,11 +169,12 @@ static void virtscsi_req_done(struct virtqueue *vq)
> virtscsi_vq_done(vq, virtscsi_complete_cmd);
> };
>
> -/* These are still stubs. */
> static void virtscsi_complete_free(void *buf)
> {
> struct virtio_scsi_cmd *cmd = buf;
>
> + if (cmd->comp)
> + complete_all(cmd->comp);
> mempool_free(cmd, virtscsi_cmd_pool);
> }
>
> @@ -306,12 +308,81 @@ out:
> return ret;
> }
>
> +static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
> +{
> + DECLARE_COMPLETION_ONSTACK(comp);
> + int ret;
> +
> + cmd->comp = &comp;
> + ret = virtscsi_kick_cmd(vscsi, vscsi->ctrl_vq, cmd,
> + sizeof cmd->req.tmf, sizeof cmd->resp.tmf,
> + GFP_NOIO);
> + if (ret < 0)
> + return FAILED;
> +
> + wait_for_completion(&comp);
> + if (cmd->resp.tmf.response != VIRTIO_SCSI_S_OK &&
> + cmd->resp.tmf.response != VIRTIO_SCSI_S_FUNCTION_SUCCEEDED)
> + return FAILED;
> +
> + return SUCCESS;
> +}

Hi Paolo,

This is against v5.

From 34ef5e64fc205044e4326fcc5dcf2aa6b219763a Mon Sep 17 00:00:00 2001
From: Hu Tao <hutao@cn.fujitsu.com>
Date: Mon, 19 Mar 2012 15:58:22 +0800
Subject: [PATCH] fix two problems in tmf

This patch fix two problems in tmf:

1. race in virtscsi_tmf that the cmd may have been already freed
when waking up from the completion

2. cmd leak if virtscsi_kick_cmd fails.


Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
---
drivers/scsi/virtio_scsi.c | 17 ++++++++++-------
1 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index efccd72..3b8a6e6 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -175,7 +175,8 @@ static void virtscsi_complete_free(void *buf)

if (cmd->comp)
complete_all(cmd->comp);
- mempool_free(cmd, virtscsi_cmd_pool);
+ else
+ mempool_free(cmd, virtscsi_cmd_pool);
}

static void virtscsi_ctrl_done(struct virtqueue *vq)
@@ -311,21 +312,23 @@ out:
static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
{
DECLARE_COMPLETION_ONSTACK(comp);
- int ret;
+ int ret = FAILED;

cmd->comp = &comp;
ret = virtscsi_kick_cmd(vscsi, vscsi->ctrl_vq, cmd,
sizeof cmd->req.tmf, sizeof cmd->resp.tmf,
GFP_NOIO);
if (ret < 0)
- return FAILED;
+ goto failed;

wait_for_completion(&comp);
- if (cmd->resp.tmf.response != VIRTIO_SCSI_S_OK &&
- cmd->resp.tmf.response != VIRTIO_SCSI_S_FUNCTION_SUCCEEDED)
- return FAILED;
+ if (cmd->resp.tmf.response == VIRTIO_SCSI_S_OK ||
+ cmd->resp.tmf.response == VIRTIO_SCSI_S_FUNCTION_SUCCEEDED)
+ ret = SUCCESS;

- return SUCCESS;
+failed:
+ mempool_free(cmd, virtscsi_cmd_pool);
+ return ret;
}

static int virtscsi_device_reset(struct scsi_cmnd *sc)
--
1.7.1
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