[dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[Yongseok Koh]

Tx descriptor for TSO embeds packet header to be replicated. If Tx inline
is enabled, there could be additional packet data inlined with 4B inline
header ahead. And between the header and additional inlined packet data,
there may be padding to make the inline part aligned to
MLX5_WQE_DWORD_SIZE. In calculating the total size of inlined data, the
size of inline header and padding is missing.

Fixes: 3f13f8c23a7c ("net/mlx5: support hardware TSO")
Cc: stable@dpdk.org

Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
---
 drivers/net/mlx5/mlx5_rxtx.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index fe9e7eac0..f89fa40b5 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -454,6 +454,7 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 			length -= pkt_inline_sz;
 			addr += pkt_inline_sz;
 		}
+		raw += MLX5_WQE_DWORD_SIZE;
 		if (txq->tso_en) {
 			tso = buf->ol_flags & PKT_TX_TCP_SEG;
 			if (tso) {
@@ -486,7 +487,6 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 				copy_b = tso_header_sz - pkt_inline_sz;
 				/* First seg must contain all headers. */
 				assert(copy_b <= length);
-				raw += MLX5_WQE_DWORD_SIZE;
 				if (copy_b &&
 				   ((end - (uintptr_t)raw) > copy_b)) {
 					uint16_t n = (MLX5_WQE_DS(copy_b) -
@@ -499,14 +499,11 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 						   (void *)addr, copy_b);
 					addr += copy_b;
 					length -= copy_b;
+					/* Include padding for TSO header. */
+					copy_b = MLX5_WQE_DS(copy_b) *
+						 MLX5_WQE_DWORD_SIZE;
 					pkt_inline_sz += copy_b;
-					/*
-					 * Another DWORD will be added
-					 * in the inline part.
-					 */
-					raw += MLX5_WQE_DS(copy_b) *
-					       MLX5_WQE_DWORD_SIZE -
-					       MLX5_WQE_DWORD_SIZE;
+					raw += copy_b;
 				} else {
 					/* NOP WQE. */
 					wqe->ctrl = (rte_v128u32_t){
@@ -524,19 +521,20 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 		}
 		/* Inline if enough room. */
 		if (inline_en || tso) {
+			uint32_t inl;
 			uintptr_t end = (uintptr_t)
 				(((uintptr_t)txq->wqes) +
 				 (1 << txq->wqe_n) * MLX5_WQE_SIZE);
 			unsigned int inline_room = max_inline *
 						   RTE_CACHE_LINE_SIZE -
-						   (pkt_inline_sz - 2);
+						   (pkt_inline_sz - 2) -
+						   !!tso * sizeof(inl);
 			uintptr_t addr_end = (addr + inline_room) &
 					     ~(RTE_CACHE_LINE_SIZE - 1);
 			unsigned int copy_b = (addr_end > addr) ?
 				RTE_MIN((addr_end - addr), length) :
 				0;
 
-			raw += MLX5_WQE_DWORD_SIZE;
 			if (copy_b && ((end - (uintptr_t)raw) > copy_b)) {
 				/*
 				 * One Dseg remains in the current WQE.  To
@@ -549,12 +547,7 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 					break;
 				max_wqe -= n;
 				if (tso) {
-					uint32_t inl =
-						htonl(copy_b | MLX5_INLINE_SEG);
-
-					pkt_inline_sz =
-						MLX5_WQE_DS(tso_header_sz) *
-						MLX5_WQE_DWORD_SIZE;
+					inl = htonl(copy_b | MLX5_INLINE_SEG);
 					rte_memcpy((void *)raw,
 						   (void *)&inl, sizeof(inl));
 					raw += sizeof(inl);
-- 
2.11.0

Re: [dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[Nélio Laranjeiro]

Hi Yongseok,

Please see some comments below,

On Thu, Aug 31, 2017 at 09:27:06AM -0700, Yongseok Koh wrote:
> Tx descriptor for TSO embeds packet header to be replicated. If Tx inline
> is enabled, there could be additional packet data inlined with 4B inline
> header ahead. And between the header and additional inlined packet data,
> there may be padding to make the inline part aligned to
> MLX5_WQE_DWORD_SIZE. In calculating the total size of inlined data, the
> size of inline header and padding is missing.
> 
> Fixes: 3f13f8c23a7c ("net/mlx5: support hardware TSO")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> ---
>  drivers/net/mlx5/mlx5_rxtx.c | 25 +++++++++----------------
>  1 file changed, 9 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
> index fe9e7eac0..f89fa40b5 100644
> --- a/drivers/net/mlx5/mlx5_rxtx.c
> +++ b/drivers/net/mlx5/mlx5_rxtx.c
> @@ -524,19 +521,20 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
>  		}
>  		/* Inline if enough room. */
>  		if (inline_en || tso) {
> +			uint32_t inl;
>  			uintptr_t end = (uintptr_t)
>  				(((uintptr_t)txq->wqes) +
>  				 (1 << txq->wqe_n) * MLX5_WQE_SIZE);
>  			unsigned int inline_room = max_inline *
>  						   RTE_CACHE_LINE_SIZE -
> -						   (pkt_inline_sz - 2);
> +						   (pkt_inline_sz - 2) -
> +						   !!tso * sizeof(inl);

Is not it dangerous to assume inl will always be 4 bytes long?  Why not
writing the real value instead?

>  			uintptr_t addr_end = (addr + inline_room) &
>  					     ~(RTE_CACHE_LINE_SIZE - 1);
>  			unsigned int copy_b = (addr_end > addr) ?
>  				RTE_MIN((addr_end - addr), length) :
>  				0;
>  
> -			raw += MLX5_WQE_DWORD_SIZE;
>  			if (copy_b && ((end - (uintptr_t)raw) > copy_b)) {
>  				/*
>  				 * One Dseg remains in the current WQE.  To

Thanks,

-- 
Nélio Laranjeiro
6WIND

Re: [dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[Yongseok Koh]

On Mon, Sep 04, 2017 at 04:01:08PM +0200, Nélio Laranjeiro wrote:
> Hi Yongseok,
> 
> Please see some comments below,
> 
> On Thu, Aug 31, 2017 at 09:27:06AM -0700, Yongseok Koh wrote:
> > Tx descriptor for TSO embeds packet header to be replicated. If Tx inline
> > is enabled, there could be additional packet data inlined with 4B inline
> > header ahead. And between the header and additional inlined packet data,
> > there may be padding to make the inline part aligned to
> > MLX5_WQE_DWORD_SIZE. In calculating the total size of inlined data, the
> > size of inline header and padding is missing.
> > 
> > Fixes: 3f13f8c23a7c ("net/mlx5: support hardware TSO")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
> > Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> > ---
> >  drivers/net/mlx5/mlx5_rxtx.c | 25 +++++++++----------------
> >  1 file changed, 9 insertions(+), 16 deletions(-)
> > 
> > diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
> > index fe9e7eac0..f89fa40b5 100644
> > --- a/drivers/net/mlx5/mlx5_rxtx.c
> > +++ b/drivers/net/mlx5/mlx5_rxtx.c
> > @@ -524,19 +521,20 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
> >  		}
> >  		/* Inline if enough room. */
> >  		if (inline_en || tso) {
> > +			uint32_t inl;
> >  			uintptr_t end = (uintptr_t)
> >  				(((uintptr_t)txq->wqes) +
> >  				 (1 << txq->wqe_n) * MLX5_WQE_SIZE);
> >  			unsigned int inline_room = max_inline *
> >  						   RTE_CACHE_LINE_SIZE -
> > -						   (pkt_inline_sz - 2);
> > +						   (pkt_inline_sz - 2) -
> > +						   !!tso * sizeof(inl);
> 
> Is not it dangerous to assume inl will always be 4 bytes long?  Why not
> writing the real value instead?
That was for readability of the code and uint32_t will be always 4bytes. But for
better readability, it should be 'inline_header' instead of 'inl' though. I'm
also okay with using "4" as well. Which way do you prefer?

Thanks,
Yongseok

Re: [dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[Nélio Laranjeiro]

On Mon, Sep 11, 2017 at 03:17:44PM -0700, Yongseok Koh wrote:
> On Mon, Sep 04, 2017 at 04:01:08PM +0200, Nélio Laranjeiro wrote:
> > Hi Yongseok,
> > 
> > Please see some comments below,
> > 
> > On Thu, Aug 31, 2017 at 09:27:06AM -0700, Yongseok Koh wrote:
> > > Tx descriptor for TSO embeds packet header to be replicated. If Tx inline
> > > is enabled, there could be additional packet data inlined with 4B inline
> > > header ahead. And between the header and additional inlined packet data,
> > > there may be padding to make the inline part aligned to
> > > MLX5_WQE_DWORD_SIZE. In calculating the total size of inlined data, the
> > > size of inline header and padding is missing.
> > > 
> > > Fixes: 3f13f8c23a7c ("net/mlx5: support hardware TSO")
> > > Cc: stable@dpdk.org
> > > 
> > > Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
> > > Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> > > ---
> > >  drivers/net/mlx5/mlx5_rxtx.c | 25 +++++++++----------------
> > >  1 file changed, 9 insertions(+), 16 deletions(-)
> > > 
> > > diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
> > > index fe9e7eac0..f89fa40b5 100644
> > > --- a/drivers/net/mlx5/mlx5_rxtx.c
> > > +++ b/drivers/net/mlx5/mlx5_rxtx.c
> > > @@ -524,19 +521,20 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
> > >  		}
> > >  		/* Inline if enough room. */
> > >  		if (inline_en || tso) {
> > > +			uint32_t inl;
> > >  			uintptr_t end = (uintptr_t)
> > >  				(((uintptr_t)txq->wqes) +
> > >  				 (1 << txq->wqe_n) * MLX5_WQE_SIZE);
> > >  			unsigned int inline_room = max_inline *
> > >  						   RTE_CACHE_LINE_SIZE -
> > > -						   (pkt_inline_sz - 2);
> > > +						   (pkt_inline_sz - 2) -
> > > +						   !!tso * sizeof(inl);
> > 
> > Is not it dangerous to assume inl will always be 4 bytes long?  Why not
> > writing the real value instead?
> That was for readability of the code and uint32_t will be always 4bytes. But for
> better readability, it should be 'inline_header' instead of 'inl' though. I'm
> also okay with using "4" as well. Which way do you prefer?

I agree on both, I was not clear enough to explain my thought, if for some
reason the inl moves from uint32_t to uint16_t without touching the sizeof
later, it will cause an issue.

Thanks,

-- 
Nélio Laranjeiro
6WIND

Re: [dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[Yongseok Koh]

> On Sep 12, 2017, at 12:24 AM, Nélio Laranjeiro <nelio.laranjeiro@6wind.com> wrote:
> 
> On Mon, Sep 11, 2017 at 03:17:44PM -0700, Yongseok Koh wrote:
>> On Mon, Sep 04, 2017 at 04:01:08PM +0200, Nélio Laranjeiro wrote:
>>> Hi Yongseok,
>>> 
>>> Please see some comments below,
>>> 
>>> On Thu, Aug 31, 2017 at 09:27:06AM -0700, Yongseok Koh wrote:
>>>> Tx descriptor for TSO embeds packet header to be replicated. If Tx inline
>>>> is enabled, there could be additional packet data inlined with 4B inline
>>>> header ahead. And between the header and additional inlined packet data,
>>>> there may be padding to make the inline part aligned to
>>>> MLX5_WQE_DWORD_SIZE. In calculating the total size of inlined data, the
>>>> size of inline header and padding is missing.
>>>> 
>>>> Fixes: 3f13f8c23a7c ("net/mlx5: support hardware TSO")
>>>> Cc: stable@dpdk.org
>>>> 
>>>> Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
>>>> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
>>>> ---
>>>> drivers/net/mlx5/mlx5_rxtx.c | 25 +++++++++----------------
>>>> 1 file changed, 9 insertions(+), 16 deletions(-)
>>>> 
>>>> diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
>>>> index fe9e7eac0..f89fa40b5 100644
>>>> --- a/drivers/net/mlx5/mlx5_rxtx.c
>>>> +++ b/drivers/net/mlx5/mlx5_rxtx.c
>>>> @@ -524,19 +521,20 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
>>>> 		}
>>>> 		/* Inline if enough room. */
>>>> 		if (inline_en || tso) {
>>>> +			uint32_t inl;
>>>> 			uintptr_t end = (uintptr_t)
>>>> 				(((uintptr_t)txq->wqes) +
>>>> 				 (1 << txq->wqe_n) * MLX5_WQE_SIZE);
>>>> 			unsigned int inline_room = max_inline *
>>>> 						   RTE_CACHE_LINE_SIZE -
>>>> -						   (pkt_inline_sz - 2);
>>>> +						   (pkt_inline_sz - 2) -
>>>> +						   !!tso * sizeof(inl);
>>> 
>>> Is not it dangerous to assume inl will always be 4 bytes long?  Why not
>>> writing the real value instead?
>> That was for readability of the code and uint32_t will be always 4bytes. But for
>> better readability, it should be 'inline_header' instead of 'inl' though. I'm
>> also okay with using "4" as well. Which way do you prefer?
> 
> I agree on both, I was not clear enough to explain my thought, if for some
> reason the inl moves from uint32_t to uint16_t without touching the sizeof
> later, it will cause an issue.

I tried to change the sizeof but I found that there are more "sizeof(inl)" in
the following lines. Changing all the sizeof would be beyond the scope of this
patch. So, how about leaving it as is for consistency?

Thanks
Yongseok

Re: [dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[Shahaf Shuler]

Tuesday, September 12, 2017 9:34 PM, Nélio Laranjeiro:
> > On Sep 12, 2017, at 12:24 AM, Nélio Laranjeiro
> >>> Is not it dangerous to assume inl will always be 4 bytes long?  Why
> >>> not writing the real value instead?
> >> That was for readability of the code and uint32_t will be always
> >> 4bytes. But for better readability, it should be 'inline_header'
> >> instead of 'inl' though. I'm also okay with using "4" as well. Which way do
> you prefer?
> >
> > I agree on both, I was not clear enough to explain my thought, if for
> > some reason the inl moves from uint32_t to uint16_t without touching
> > the sizeof later, it will cause an issue.
> 
> I tried to change the sizeof but I found that there are more "sizeof(inl)" in the
> following lines. Changing all the sizeof would be beyond the scope of this
> patch. So, how about leaving it as is for consistency?

The inline segment format is not expected to change so easily. It is parsed by the HW and HW maintains backward compatibility for all of the WQE structures. 

> 
> Thanks
> Yongseok
> 
> 
> 
> 

Re: [dpdk-dev] [PATCH] net/mlx5: fix calculating TSO inline size

[Nélio Laranjeiro]

On Wed, Sep 13, 2017 at 05:05:14AM +0000, Shahaf Shuler wrote:
> Tuesday, September 12, 2017 9:34 PM, Nélio Laranjeiro:
> > > On Sep 12, 2017, at 12:24 AM, Nélio Laranjeiro
> > >>> Is not it dangerous to assume inl will always be 4 bytes long?  Why
> > >>> not writing the real value instead?
> > >> That was for readability of the code and uint32_t will be always
> > >> 4bytes. But for better readability, it should be 'inline_header'
> > >> instead of 'inl' though. I'm also okay with using "4" as well. Which way do
> > you prefer?
> > >
> > > I agree on both, I was not clear enough to explain my thought, if for
> > > some reason the inl moves from uint32_t to uint16_t without touching
> > > the sizeof later, it will cause an issue.
> > 
> > I tried to change the sizeof but I found that there are more "sizeof(inl)" in the
> > following lines. Changing all the sizeof would be beyond the scope of this
> > patch. So, how about leaving it as is for consistency?
> 
> The inline segment format is not expected to change so easily. It is parsed
> by the HW and HW maintains backward compatibility for all of the WQE
> structures. 

We are not talking here about the hardware behavior but about wrong ways to
define hardware values which should be used trough define and not by size of
variable which can be wrongly modified.
If the hardware inline_header size of 4, it should be defined as is.

I won't block this patch as it is not the single place where this sizeof is
used, but it should be replaced as soon as possible by a define to avoid wrong
behaviors in the future.

Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>

-- 
Nélio Laranjeiro
6WIND

Re: [dpdk-dev] [dpdk-stable] [PATCH] net/mlx5: fix calculating TSO inline size

[Ferruh Yigit]

On 9/13/2017 8:26 AM, Nélio Laranjeiro wrote:
> On Wed, Sep 13, 2017 at 05:05:14AM +0000, Shahaf Shuler wrote:
>> Tuesday, September 12, 2017 9:34 PM, Nélio Laranjeiro:
>>>> On Sep 12, 2017, at 12:24 AM, Nélio Laranjeiro
>>>>>> Is not it dangerous to assume inl will always be 4 bytes long?  Why
>>>>>> not writing the real value instead?
>>>>> That was for readability of the code and uint32_t will be always
>>>>> 4bytes. But for better readability, it should be 'inline_header'
>>>>> instead of 'inl' though. I'm also okay with using "4" as well. Which way do
>>> you prefer?
>>>>
>>>> I agree on both, I was not clear enough to explain my thought, if for
>>>> some reason the inl moves from uint32_t to uint16_t without touching
>>>> the sizeof later, it will cause an issue.
>>>
>>> I tried to change the sizeof but I found that there are more "sizeof(inl)" in the
>>> following lines. Changing all the sizeof would be beyond the scope of this
>>> patch. So, how about leaving it as is for consistency?
>>
>> The inline segment format is not expected to change so easily. It is parsed
>> by the HW and HW maintains backward compatibility for all of the WQE
>> structures. 
> 
> We are not talking here about the hardware behavior but about wrong ways to
> define hardware values which should be used trough define and not by size of
> variable which can be wrongly modified.
> If the hardware inline_header size of 4, it should be defined as is.
> 
> I won't block this patch as it is not the single place where this sizeof is
> used, but it should be replaced as soon as possible by a define to avoid wrong
> behaviors in the future.
> 
> Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>

Applied to dpdk-next-net/master, thanks.