[PATCH v2] scsi: zero per-cmd driver data before each I/O

[PATCH v2] scsi: zero per-cmd driver data before each I/O

[Christoph Hellwig]

Without this drivers that don't clear the state themselves can see off
effects.  For example Hyper-V VMs using the storvsc driver will often
hang during boot due to uncleared Test Unit Ready failures.

Fixes: e9c787e6 ("scsi: allocate scsi_cmnd structures as part of struct request")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Dexuan Cui <decui@microsoft.com>
Tested-by: Dexuan Cui <decui@microsoft.com>
---

Changes since V1:
 - use a single memset as suggested by Bart

 drivers/scsi/scsi_lib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 90f65c8f487a..1d87a809944d 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1166,7 +1166,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
 
 	/* zero out the cmd, except for the embedded scsi_request */
 	memset((char *)cmd + sizeof(cmd->req), 0,
-		sizeof(*cmd) - sizeof(cmd->req));
+		sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);
 
 	cmd->device = dev;
 	cmd->sense_buffer = buf;
-- 
2.11.0

Re: [PATCH v2] scsi: zero per-cmd driver data before each I/O

[Bart Van Assche]

On 02/21/2017 01:29 AM, Christoph Hellwig wrote:=0A=
> Without this drivers that don't clear the state themselves can see off=0A=
> effects.  For example Hyper-V VMs using the storvsc driver will often=0A=
> hang during boot due to uncleared Test Unit Ready failures.=0A=
> =0A=
> Fixes: e9c787e6 ("scsi: allocate scsi_cmnd structures as part of struct r=
equest")=0A=
> Signed-off-by: Christoph Hellwig <hch@lst.de>=0A=
> Reported-by: Dexuan Cui <decui@microsoft.com>=0A=
> Tested-by: Dexuan Cui <decui@microsoft.com>=0A=
> ---=0A=
> =0A=
> Changes since V1:=0A=
>  - use a single memset as suggested by Bart=0A=
> =0A=
>  drivers/scsi/scsi_lib.c | 2 +-=0A=
>  1 file changed, 1 insertion(+), 1 deletion(-)=0A=
> =0A=
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c=0A=
> index 90f65c8f487a..1d87a809944d 100644=0A=
> --- a/drivers/scsi/scsi_lib.c=0A=
> +++ b/drivers/scsi/scsi_lib.c=0A=
> @@ -1166,7 +1166,7 @@ void scsi_init_command(struct scsi_device *dev, str=
uct scsi_cmnd *cmd)=0A=
>  =0A=
>  	/* zero out the cmd, except for the embedded scsi_request */=0A=
>  	memset((char *)cmd + sizeof(cmd->req), 0,=0A=
> -		sizeof(*cmd) - sizeof(cmd->req));=0A=
> +		sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);=0A=
>  =0A=
>  	cmd->device =3D dev;=0A=
>  	cmd->sense_buffer =3D buf;=0A=
=0A=
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>=0A=
=0A=
=0A=

Re: [PATCH v2] scsi: zero per-cmd driver data before each I/O

[Bart Van Assche]

On 02/21/2017 01:29 AM, Christoph Hellwig wrote:
> Without this drivers that don't clear the state themselves can see off
> effects.  For example Hyper-V VMs using the storvsc driver will often
> hang during boot due to uncleared Test Unit Ready failures.
> 
> Fixes: e9c787e6 ("scsi: allocate scsi_cmnd structures as part of struct request")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reported-by: Dexuan Cui <decui@microsoft.com>
> Tested-by: Dexuan Cui <decui@microsoft.com>
> ---
> 
> Changes since V1:
>  - use a single memset as suggested by Bart
> 
>  drivers/scsi/scsi_lib.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 90f65c8f487a..1d87a809944d 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1166,7 +1166,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
>  
>  	/* zero out the cmd, except for the embedded scsi_request */
>  	memset((char *)cmd + sizeof(cmd->req), 0,
> -		sizeof(*cmd) - sizeof(cmd->req));
> +		sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);
>  
>  	cmd->device = dev;
>  	cmd->sense_buffer = buf;

Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>

Re: [PATCH v2] scsi: zero per-cmd driver data before each I/O

[Jens Axboe]

On 02/21/2017 02:04 AM, Christoph Hellwig wrote:
> Without this drivers that don't clear the state themselves can see off
> effects.  For example Hyper-V VMs using the storvsc driver will often
> hang during boot due to uncleared Test Unit Ready failures.
> 
> Fixes: e9c787e6 ("scsi: allocate scsi_cmnd structures as part of struct request")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reported-by: Dexuan Cui <decui@microsoft.com>
> Tested-by: Dexuan Cui <decui@microsoft.com>
> ---
> 
> Changes since V1:
>  - use a single memset as suggested by Bart

That's much better. I'll queue this up for the next pull in this merge
window.

-- 
Jens Axboe