2017-04-18 23:32:33

by Logan Gunthorpe

Subject: [PATCH] nvmet: convert from kmap to nvmet_copy_from_sgl

This is safer as it doesn't rely on the data being stored in
a single page in an sgl.

It also aids our effort to start phasing out users of sg_page. See [1].

For this we kmalloc some memory, copy to it and free at the end. Note:
we can't allocate this memory on the stack as the kbuild test robot
reports some frame size overflows on i386.

[1] https://lwn.net/Articles/720053/

Signed-off-by: Logan Gunthorpe <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Sagi Grimberg <[email protected]>
---
drivers/nvme/target/fabrics-cmd.c | 32 +++++++++++++++++++++++++-------
1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
index 8bd022af..2e0ab10 100644
--- a/drivers/nvme/target/fabrics-cmd.c
+++ b/drivers/nvme/target/fabrics-cmd.c
@@ -122,7 +122,15 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
struct nvmet_ctrl *ctrl = NULL;
u16 status = 0;

- d = kmap(sg_page(req->sg)) + req->sg->offset;
+ d = kmalloc(sizeof(*d), GFP_KERNEL);
+ if (!d) {
+ status = NVME_SC_INTERNAL;
+ goto complete;
+ }
+
+ status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
+ if (status)
+ goto out;

/* zero out initial completion result, assign values as needed */
req->rsp->result.u32 = 0;
@@ -143,7 +151,7 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
}

status = nvmet_alloc_ctrl(d->subsysnqn, d->hostnqn, req,
- le32_to_cpu(c->kato), &ctrl);
+ le32_to_cpu(c->kato), &ctrl);
if (status)
goto out;

@@ -158,7 +166,8 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
req->rsp->result.u16 = cpu_to_le16(ctrl->cntlid);

out:
- kunmap(sg_page(req->sg));
+ kfree(d);
+complete:
nvmet_req_complete(req, status);
}

@@ -170,7 +179,15 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
u16 qid = le16_to_cpu(c->qid);
u16 status = 0;

- d = kmap(sg_page(req->sg)) + req->sg->offset;
+ d = kmalloc(sizeof(*d), GFP_KERNEL);
+ if (!d) {
+ status = NVME_SC_INTERNAL;
+ goto complete;
+ }
+
+ status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
+ if (status)
+ goto out;

/* zero out initial completion result, assign values as needed */
req->rsp->result.u32 = 0;
@@ -183,8 +200,8 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
}

status = nvmet_ctrl_find_get(d->subsysnqn, d->hostnqn,
- le16_to_cpu(d->cntlid),
- req, &ctrl);
+ le16_to_cpu(d->cntlid),
+ req, &ctrl);
if (status)
goto out;

@@ -205,7 +222,8 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
pr_info("adding queue %d to ctrl %d.\n", qid, ctrl->cntlid);

out:
- kunmap(sg_page(req->sg));
+ kfree(d);
+complete:
nvmet_req_complete(req, status);
return;

--
2.1.4

2017-04-19 09:33:45

by Max Gurtovoy

Subject: Re: [PATCH] nvmet: convert from kmap to nvmet_copy_from_sgl

Hi Logan,

On 4/19/2017 2:32 AM, Logan Gunthorpe wrote:
> This is safer as it doesn't rely on the data being stored in
> a single page in an sgl.
>
> It also aids our effort to start phasing out users of sg_page. See [1].
>
> For this we kmalloc some memory, copy to it and free at the end. Note:
> we can't allocate this memory on the stack as the kbuild test robot
> reports some frame size overflows on i386.
>
> [1] https://lwn.net/Articles/720053/
>
> Signed-off-by: Logan Gunthorpe <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Sagi Grimberg <[email protected]>
> ---
> drivers/nvme/target/fabrics-cmd.c | 32 +++++++++++++++++++++++++-------
> 1 file changed, 25 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
> index 8bd022af..2e0ab10 100644
> --- a/drivers/nvme/target/fabrics-cmd.c
> +++ b/drivers/nvme/target/fabrics-cmd.c
> @@ -122,7 +122,15 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
> struct nvmet_ctrl *ctrl = NULL;
> u16 status = 0;
>
> - d = kmap(sg_page(req->sg)) + req->sg->offset;
> + d = kmalloc(sizeof(*d), GFP_KERNEL);

I'd prefer removing the dynamic allocation and use d on the stack to
simplify the code.
Any thoughts ?

> + if (!d) {
> + status = NVME_SC_INTERNAL;
> + goto complete;
> + }
> +
> + status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
> + if (status)
> + goto out;
>
> /* zero out initial completion result, assign values as needed */
> req->rsp->result.u32 = 0;
> @@ -143,7 +151,7 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
> }
>
> status = nvmet_alloc_ctrl(d->subsysnqn, d->hostnqn, req,
> - le32_to_cpu(c->kato), &ctrl);
> + le32_to_cpu(c->kato), &ctrl);
> if (status)
> goto out;
>
> @@ -158,7 +166,8 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
> req->rsp->result.u16 = cpu_to_le16(ctrl->cntlid);
>
> out:
> - kunmap(sg_page(req->sg));
> + kfree(d);
> +complete:
> nvmet_req_complete(req, status);
> }
>
> @@ -170,7 +179,15 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
> u16 qid = le16_to_cpu(c->qid);
> u16 status = 0;
>
> - d = kmap(sg_page(req->sg)) + req->sg->offset;
> + d = kmalloc(sizeof(*d), GFP_KERNEL);

here too.

> + if (!d) {
> + status = NVME_SC_INTERNAL;
> + goto complete;
> + }
> +
> + status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
> + if (status)
> + goto out;
>
> /* zero out initial completion result, assign values as needed */
> req->rsp->result.u32 = 0;
> @@ -183,8 +200,8 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
> }
>
> status = nvmet_ctrl_find_get(d->subsysnqn, d->hostnqn,
> - le16_to_cpu(d->cntlid),
> - req, &ctrl);
> + le16_to_cpu(d->cntlid),
> + req, &ctrl);
> if (status)
> goto out;
>
> @@ -205,7 +222,8 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
> pr_info("adding queue %d to ctrl %d.\n", qid, ctrl->cntlid);
>
> out:
> - kunmap(sg_page(req->sg));
> + kfree(d);
> +complete:
> nvmet_req_complete(req, status);
> return;
>
>

2017-04-19 09:38:31

by Johannes Thumshirn

Subject: Re: [PATCH] nvmet: convert from kmap to nvmet_copy_from_sgl

On Wed, Apr 19, 2017 at 12:33:09PM +0300, Max Gurtovoy wrote:
> Hi Logan,
>
> On 4/19/2017 2:32 AM, Logan Gunthorpe wrote:
> >This is safer as it doesn't rely on the data being stored in
> >a single page in an sgl.
> >
> >It also aids our effort to start phasing out users of sg_page. See [1].
> >
> >For this we kmalloc some memory, copy to it and free at the end. Note:
> >we can't allocate this memory on the stack as the kbuild test robot
> >reports some frame size overflows on i386.
> >
> >[1] https://lwn.net/Articles/720053/
> >
> >Signed-off-by: Logan Gunthorpe <[email protected]>
> >Cc: Christoph Hellwig <[email protected]>
> >Cc: Sagi Grimberg <[email protected]>
> >---
> > drivers/nvme/target/fabrics-cmd.c | 32 +++++++++++++++++++++++++-------
> > 1 file changed, 25 insertions(+), 7 deletions(-)
> >
> >diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
> >index 8bd022af..2e0ab10 100644
> >--- a/drivers/nvme/target/fabrics-cmd.c
> >+++ b/drivers/nvme/target/fabrics-cmd.c
> >@@ -122,7 +122,15 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
> > struct nvmet_ctrl *ctrl = NULL;
> > u16 status = 0;
> >
> >- d = kmap(sg_page(req->sg)) + req->sg->offset;
> >+ d = kmalloc(sizeof(*d), GFP_KERNEL);
>
> I'd prefer removing the dynamic allocation and use d on the stack to
> simplify the code.
> Any thoughts ?

Hi Max,

Pasting from above:

> >we can't allocate this memory on the stack as the kbuild test robot
> >reports some frame size overflows on i386.


--
Johannes Thumshirn Storage
[email protected] +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: Felix Imend?rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N?rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

2017-04-19 09:45:38

by Max Gurtovoy

Subject: Re: [PATCH] nvmet: convert from kmap to nvmet_copy_from_sgl

On 4/19/2017 12:38 PM, Johannes Thumshirn wrote:
> On Wed, Apr 19, 2017 at 12:33:09PM +0300, Max Gurtovoy wrote:
>> Hi Logan,
>>
>> On 4/19/2017 2:32 AM, Logan Gunthorpe wrote:
>>> This is safer as it doesn't rely on the data being stored in
>>> a single page in an sgl.
>>>
>>> It also aids our effort to start phasing out users of sg_page. See [1].
>>>
>>> For this we kmalloc some memory, copy to it and free at the end. Note:
>>> we can't allocate this memory on the stack as the kbuild test robot
>>> reports some frame size overflows on i386.
>>>
>>> [1] https://lwn.net/Articles/720053/
>>>
>>> Signed-off-by: Logan Gunthorpe <[email protected]>
>>> Cc: Christoph Hellwig <[email protected]>
>>> Cc: Sagi Grimberg <[email protected]>
>>> ---
>>> drivers/nvme/target/fabrics-cmd.c | 32 +++++++++++++++++++++++++-------
>>> 1 file changed, 25 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
>>> index 8bd022af..2e0ab10 100644
>>> --- a/drivers/nvme/target/fabrics-cmd.c
>>> +++ b/drivers/nvme/target/fabrics-cmd.c
>>> @@ -122,7 +122,15 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
>>> struct nvmet_ctrl *ctrl = NULL;
>>> u16 status = 0;
>>>
>>> - d = kmap(sg_page(req->sg)) + req->sg->offset;
>>> + d = kmalloc(sizeof(*d), GFP_KERNEL);
>>
>> I'd prefer removing the dynamic allocation and use d on the stack to
>> simplify the code.
>> Any thoughts ?
>
> Hi Max,
>
> Pasting from above:
>
>>> we can't allocate this memory on the stack as the kbuild test robot
>>> reports some frame size overflows on i386.

Thanks Johannes, I missed that comment.

Looks good,

Reviewed-by: Max Gurtovoy <[email protected]>

>
>

2017-04-19 15:41:06

by Logan Gunthorpe

Subject: Re: [PATCH] nvmet: convert from kmap to nvmet_copy_from_sgl

Thanks Max!

On 19/04/17 03:44 AM, Max Gurtovoy wrote:
> Looks good,
>
> Reviewed-by: Max Gurtovoy <[email protected]>

2017-04-19 19:32:58

by Christoph Hellwig

Subject: Re: [PATCH] nvmet: convert from kmap to nvmet_copy_from_sgl

Looks good,

Reviewed-by: Christoph Hellwig <[email protected]>

2017-04-20 11:31:56

by Sagi Grimberg

Subject: Re: [PATCH] nvmet: convert from kmap to nvmet_copy_from_sgl

Reviewed-by: Sagi Grimberg <[email protected]>