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[PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality

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  [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality Murali Karicheri <m-karicheri2@ti.com> - 2016-02-18 20:50 +0100
    Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality Arnd Bergmann <arnd@arndb.de> - 2016-02-19 15:50 +0100
      Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info()  functionality Murali Karicheri <m-karicheri2@ti.com> - 2016-02-19 16:50 +0100
        Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info()  functionality Murali Karicheri <m-karicheri2@ti.com> - 2016-02-19 17:50 +0100
        Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality Arnd Bergmann <arnd@arndb.de> - 2016-02-19 17:50 +0100
      Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info()  functionality Murali Karicheri <m-karicheri2@ti.com> - 2016-02-19 19:10 +0100
        Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality Arnd Bergmann <arnd@arndb.de> - 2016-02-19 22:00 +0100

#1337641 — [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality

From: Arnd Bergmann <arnd@arndb.de>

The commit 899077791403 ("netcp: try to reduce type confusion in
descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
get/set_pad_info() functionality.

The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
store DMA/MEM buffer pointer and buffer size respectively. And in both
cases for Keystone 2 the pointer type size is 32 bit regardless of
LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
is not expected to be defined.

			!LAPE	LPAE
sizeof(void*)		32bit	32bit
sizeof(dma_addr_t) 	32bit	32bit
sizeof(phys_addr_t) 	32bit	64bit

Unfortunately, above commit changed buffer's pointers save/restore
code (get/set_pad_info()) and added intermediate conversation to u64
which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
crash in RX/TX path due to "Unable to handle kernel NULL pointer"
exception. This issue was reported and discussed in [1].

Hence, fix it by partially reverting above commit and restoring
get/set_pad_info() functionality as it was before.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
Cc: Wingman Kwok <w-kwok2@ti.com>
Cc: Mugunthan V N <mugunthanvnm@ti.com>
CC: David Laight <David.Laight@ACULAB.COM>
Reported-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
---
 v1 - Just fixed a checkpatch warning for commit description
 drivers/net/ethernet/ti/netcp_core.c | 59 +++++++++++-------------------------
 1 file changed, 18 insertions(+), 41 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index c61d66d..0b26e52 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -117,20 +117,10 @@ static void get_pkt_info(dma_addr_t *buff, u32 *buff_len, dma_addr_t *ndesc,
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_pad_info(u32 *pad0, u32 *pad1, u32 *pad2, struct knav_dma_desc *desc)
+static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
 {
 	*pad0 = le32_to_cpu(desc->pad[0]);
 	*pad1 = le32_to_cpu(desc->pad[1]);
-	*pad2 = le32_to_cpu(desc->pad[2]);
-}
-
-static void get_pad_ptr(void **padptr, struct knav_dma_desc *desc)
-{
-	u64 pad64;
-
-	pad64 = le32_to_cpu(desc->pad[0]) +
-		((u64)le32_to_cpu(desc->pad[1]) << 32);
-	*padptr = (void *)(uintptr_t)pad64;
 }
 
 static void get_org_pkt_info(dma_addr_t *buff, u32 *buff_len,
@@ -163,11 +153,10 @@ static void set_desc_info(u32 desc_info, u32 pkt_info,
 	desc->packet_info = cpu_to_le32(pkt_info);
 }
 
-static void set_pad_info(u32 pad0, u32 pad1, u32 pad2, struct knav_dma_desc *desc)
+static void set_pad_info(u32 pad0, u32 pad1, struct knav_dma_desc *desc)
 {
 	desc->pad[0] = cpu_to_le32(pad0);
 	desc->pad[1] = cpu_to_le32(pad1);
-	desc->pad[2] = cpu_to_le32(pad1);
 }
 
 static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,
@@ -581,7 +570,6 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 	dma_addr_t dma_desc, dma_buf;
 	unsigned int buf_len, dma_sz = sizeof(*ndesc);
 	void *buf_ptr;
-	u32 pad[2];
 	u32 tmp;
 
 	get_words(&dma_desc, 1, &desc->next_desc);
@@ -593,14 +581,12 @@ static void netcp_free_rx_desc_chain(struct netcp_intf *netcp,
 			break;
 		}
 		get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc);
-		get_pad_ptr(&buf_ptr, ndesc);
+		get_pad_info((u32 *)&buf_ptr, &buf_len, ndesc);
 		dma_unmap_page(netcp->dev, dma_buf, PAGE_SIZE, DMA_FROM_DEVICE);
 		__free_page(buf_ptr);
 		knav_pool_desc_put(netcp->rx_pool, desc);
 	}
-
-	get_pad_info(&pad[0], &pad[1], &buf_len, desc);
-	buf_ptr = (void *)(uintptr_t)(pad[0] + ((u64)pad[1] << 32));
+	get_pad_info((u32 *)&buf_ptr, &buf_len, desc);
 
 	if (buf_ptr)
 		netcp_frag_free(buf_len <= PAGE_SIZE, buf_ptr);
@@ -639,8 +625,8 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	dma_addr_t dma_desc, dma_buff;
 	struct netcp_packet p_info;
 	struct sk_buff *skb;
-	u32 pad[2];
 	void *org_buf_ptr;
+	u32 tmp;
 
 	dma_desc = knav_queue_pop(netcp->rx_queue, &dma_sz);
 	if (!dma_desc)
@@ -653,8 +639,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	}
 
 	get_pkt_info(&dma_buff, &buf_len, &dma_desc, desc);
-	get_pad_info(&pad[0], &pad[1], &org_buf_len, desc);
-	org_buf_ptr = (void *)(uintptr_t)(pad[0] + ((u64)pad[1] << 32));
+	get_pad_info((u32 *)&org_buf_ptr, &org_buf_len, desc);
 
 	if (unlikely(!org_buf_ptr)) {
 		dev_err(netcp->ndev_dev, "NULL bufptr in desc\n");
@@ -679,7 +664,6 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 	/* Fill in the page fragment list */
 	while (dma_desc) {
 		struct page *page;
-		void *ptr;
 
 		ndesc = knav_pool_desc_unmap(netcp->rx_pool, dma_desc, dma_sz);
 		if (unlikely(!ndesc)) {
@@ -688,8 +672,7 @@ static int netcp_process_one_rx_packet(struct netcp_intf *netcp)
 		}
 
 		get_pkt_info(&dma_buff, &buf_len, &dma_desc, ndesc);
-		get_pad_ptr(&ptr, ndesc);
-		page = ptr;
+		get_pad_info((u32 *)&page, &tmp, ndesc);
 
 		if (likely(dma_buff && buf_len && page)) {
 			dma_unmap_page(netcp->dev, dma_buff, PAGE_SIZE,
@@ -767,6 +750,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 	unsigned int buf_len, dma_sz;
 	dma_addr_t dma;
 	void *buf_ptr;
+	u32 tmp;
 
 	/* Allocate descriptor */
 	while ((dma = knav_queue_pop(netcp->rx_fdq[fdq], &dma_sz))) {
@@ -777,7 +761,7 @@ static void netcp_free_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 
 		get_org_pkt_info(&dma, &buf_len, desc);
-		get_pad_ptr(&buf_ptr, desc);
+		get_pad_info((u32 *)&buf_ptr, &tmp, desc);
 
 		if (unlikely(!dma)) {
 			dev_err(netcp->ndev_dev, "NULL orig_buff in desc\n");
@@ -829,7 +813,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	struct page *page;
 	dma_addr_t dma;
 	void *bufptr;
-	u32 pad[3];
+	u32 pad[2];
 
 	/* Allocate descriptor */
 	hwdesc = knav_pool_desc_get(netcp->rx_pool);
@@ -846,7 +830,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 				SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
 		bufptr = netdev_alloc_frag(primary_buf_len);
-		pad[2] = primary_buf_len;
+		pad[1] = primary_buf_len;
 
 		if (unlikely(!bufptr)) {
 			dev_warn_ratelimited(netcp->ndev_dev,
@@ -858,9 +842,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		if (unlikely(dma_mapping_error(netcp->dev, dma)))
 			goto fail;
 
-		pad[0] = lower_32_bits((uintptr_t)bufptr);
-		pad[1] = upper_32_bits((uintptr_t)bufptr);
-
+		pad[0] = (u32)bufptr;
 	} else {
 		/* Allocate a secondary receive queue entry */
 		page = alloc_page(GFP_ATOMIC | GFP_DMA | __GFP_COLD);
@@ -870,9 +852,8 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 		}
 		buf_len = PAGE_SIZE;
 		dma = dma_map_page(netcp->dev, page, 0, buf_len, DMA_TO_DEVICE);
-		pad[0] = lower_32_bits(dma);
-		pad[1] = upper_32_bits(dma);
-		pad[2] = 0;
+		pad[0] = (u32)page;
+		pad[1] = 0;
 	}
 
 	desc_info =  KNAV_DMA_DESC_PS_INFO_IN_DESC;
@@ -882,7 +863,7 @@ static int netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
 	pkt_info |= (netcp->rx_queue_id & KNAV_DMA_DESC_RETQ_MASK) <<
 		    KNAV_DMA_DESC_RETQ_SHIFT;
 	set_org_pkt_info(dma, buf_len, hwdesc);
-	set_pad_info(pad[0], pad[1], pad[2], hwdesc);
+	set_pad_info(pad[0], pad[1], hwdesc);
 	set_desc_info(desc_info, pkt_info, hwdesc);
 
 	/* Push to FDQs */
@@ -971,11 +952,11 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 					  unsigned int budget)
 {
 	struct knav_dma_desc *desc;
-	void *ptr;
 	struct sk_buff *skb;
 	unsigned int dma_sz;
 	dma_addr_t dma;
 	int pkts = 0;
+	u32 tmp;
 
 	while (budget--) {
 		dma = knav_queue_pop(netcp->tx_compl_q, &dma_sz);
@@ -988,8 +969,7 @@ static int netcp_process_tx_compl_packets(struct netcp_intf *netcp,
 			continue;
 		}
 
-		get_pad_ptr(&ptr, desc);
-		skb = ptr;
+		get_pad_info((u32 *)&skb, &tmp, desc);
 		netcp_free_tx_desc_chain(netcp, desc, dma_sz);
 		if (!skb) {
 			dev_err(netcp->ndev_dev, "No skb in Tx desc\n");
@@ -1194,10 +1174,7 @@ static int netcp_tx_submit_skb(struct netcp_intf *netcp,
 	}
 
 	set_words(&tmp, 1, &desc->packet_info);
-	tmp = lower_32_bits((uintptr_t)&skb);
-	set_words(&tmp, 1, &desc->pad[0]);
-	tmp = upper_32_bits((uintptr_t)&skb);
-	set_words(&tmp, 1, &desc->pad[1]);
+	set_words((u32 *)&skb, 1, &desc->pad[0]);
 
 	if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
 		tmp = tx_pipe->switch_to_port;
-- 
1.9.1

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#1338246

On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The commit 899077791403 ("netcp: try to reduce type confusion in
> descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
> get/set_pad_info() functionality.
> 
> The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
> store DMA/MEM buffer pointer and buffer size respectively. And in both
> cases for Keystone 2 the pointer type size is 32 bit regardless of
> LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
> is not expected to be defined.
> 
> 			!LAPE	LPAE
> sizeof(void*)		32bit	32bit
> sizeof(dma_addr_t) 	32bit	32bit
> sizeof(phys_addr_t) 	32bit	64bit

As this was never relevant or true, I don't think it needs to be
mentioned here, it just confuses things. Please just assume that
dma_addr_t can be 64-bit wide, but will only contain 32-bit
numbers on keystone.

> Unfortunately, above commit changed buffer's pointers save/restore
> code (get/set_pad_info()) and added intermediate conversation to u64
> which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
> crash in RX/TX path due to "Unable to handle kernel NULL pointer"
> exception. This issue was reported and discussed in [1].

Have you been able to figure out why it actually broke? I'd still
like to know.

> Hence, fix it by partially reverting above commit and restoring
> get/set_pad_info() functionality as it was before.
> 
> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
> Cc: Wingman Kwok <w-kwok2@ti.com>
> Cc: Mugunthan V N <mugunthanvnm@ti.com>
> CC: David Laight <David.Laight@ACULAB.COM>
> Reported-by: Franklin S Cooper Jr <fcooper@ti.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>

I don't think I sent this patch with a 'Signed-off-by', did I?
(I could be misremembering that).

	Arnd

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#1338298 — Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality

On 02/19/2016 09:41 AM, Arnd Bergmann wrote:
> On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>>
>> The commit 899077791403 ("netcp: try to reduce type confusion in
>> descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
>> get/set_pad_info() functionality.
>>
>> The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
>> store DMA/MEM buffer pointer and buffer size respectively. And in both
>> cases for Keystone 2 the pointer type size is 32 bit regardless of
>> LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
>> is not expected to be defined.
>>
>> 			!LAPE	LPAE
>> sizeof(void*)		32bit	32bit
>> sizeof(dma_addr_t) 	32bit	32bit
>> sizeof(phys_addr_t) 	32bit	64bit
> 
> As this was never relevant or true, I don't think it needs to be
> mentioned here, it just confuses things. Please just assume that
> dma_addr_t can be 64-bit wide, but will only contain 32-bit
> numbers on keystone.
> 

I can remove this from the commit description and re-send.

>> Unfortunately, above commit changed buffer's pointers save/restore
>> code (get/set_pad_info()) and added intermediate conversation to u64
>> which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
>> crash in RX/TX path due to "Unable to handle kernel NULL pointer"
>> exception. This issue was reported and discussed in [1].
> 
> Have you been able to figure out why it actually broke? I'd still
> like to know.
> 
As Grygorii is out of office until Monday, I would like to step in.
I will take some time today to try review the reverted changes for
failure reason and get back. But as you have agreed in the discussion
at https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
Can we fix the regression by applying this patch and rest of the series
if it looks good? If I need to separate this from rest of the series,
let me know and I can take care of that.

>> Hence, fix it by partially reverting above commit and restoring
>> get/set_pad_info() functionality as it was before.
>>
>> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
>> Cc: Wingman Kwok <w-kwok2@ti.com>
>> Cc: Mugunthan V N <mugunthanvnm@ti.com>
>> CC: David Laight <David.Laight@ACULAB.COM>
>> Reported-by: Franklin S Cooper Jr <fcooper@ti.com>
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
>> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
> 
> I don't think I sent this patch with a 'Signed-off-by', did I?
> (I could be misremembering that).
> 

I think you had agreed based on what I read at
https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html

reproduced below for your convenience.
=============================================================================

> What I could do now is update your/my patch as i mentioned in [1]
> and re-send it at the weekend (with your authorship and my signoff).
> Do you agree?
> 
> 
> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95831.html

Yes, let's do that in the meantime. I can also make sure that that
the driver doesn't build on 64-bit, just in case.
=============================================================================

Hope I can keep your sign-off when I re-send this. Please confirm.

Murali

> 	Arnd
> 


-- 
Murali Karicheri
Linux Kernel, Keystone

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#1338346 — Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality

On 02/19/2016 11:41 AM, Arnd Bergmann wrote:
> On Friday 19 February 2016 10:48:30 Murali Karicheri wrote:
>> On 02/19/2016 09:41 AM, Arnd Bergmann wrote:
>>> On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:
>>>> From: Arnd Bergmann <arnd@arndb.de>
>>>>
>>>> The commit 899077791403 ("netcp: try to reduce type confusion in
>>>> descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
>>>> get/set_pad_info() functionality.
>>>>
>>>> The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
>>>> store DMA/MEM buffer pointer and buffer size respectively. And in both
>>>> cases for Keystone 2 the pointer type size is 32 bit regardless of
>>>> LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
>>>> is not expected to be defined.
>>>>
>>>>                      !LAPE   LPAE
>>>> sizeof(void*)                32bit   32bit
>>>> sizeof(dma_addr_t)   32bit   32bit
>>>> sizeof(phys_addr_t)  32bit   64bit
>>>
>>> As this was never relevant or true, I don't think it needs to be
>>> mentioned here, it just confuses things. Please just assume that
>>> dma_addr_t can be 64-bit wide, but will only contain 32-bit
>>> numbers on keystone.
>>>
>>
>> I can remove this from the commit description and re-send.
> 
> Ok
> 
>>>> Unfortunately, above commit changed buffer's pointers save/restore
>>>> code (get/set_pad_info()) and added intermediate conversation to u64
>>>> which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
>>>> crash in RX/TX path due to "Unable to handle kernel NULL pointer"
>>>> exception. This issue was reported and discussed in [1].
>>>
>>> Have you been able to figure out why it actually broke? I'd still
>>> like to know.
>>>
>> As Grygorii is out of office until Monday, I would like to step in.
>> I will take some time today to try review the reverted changes for
>> failure reason and get back. But as you have agreed in the discussion
>> at https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
>> Can we fix the regression by applying this patch and rest of the series
>> if it looks good? If I need to separate this from rest of the series,
>> let me know and I can take care of that.
> 
> Yes, sounds fine.
> 
>>>> Hence, fix it by partially reverting above commit and restoring
>>>> get/set_pad_info() functionality as it was before.
>>>>
>>>> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
>>>> Cc: Wingman Kwok <w-kwok2@ti.com>
>>>> Cc: Mugunthan V N <mugunthanvnm@ti.com>
>>>> CC: David Laight <David.Laight@ACULAB.COM>
>>>> Reported-by: Franklin S Cooper Jr <fcooper@ti.com>
>>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>>>> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
>>>> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
>>>
>>> I don't think I sent this patch with a 'Signed-off-by', did I?
>>> (I could be misremembering that).
>>>
>>
>> I think you had agreed based on what I read at
>> https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
>>
>> reproduced below for your convenience.
>> =============================================================================
>>
>>> What I could do now is update your/my patch as i mentioned in [1]
>>> and re-send it at the weekend (with your authorship and my signoff).
>>> Do you agree?
>>>
>>>
>>> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95831.html
>>
>> Yes, let's do that in the meantime. I can also make sure that that
>> the driver doesn't build on 64-bit, just in case.
>> =============================================================================
>>
>> Hope I can keep your sign-off when I re-send this. Please confirm.
> 
> The most important part here is that you don't add a "Signed-off-by"
> tag unless it was provided by that person as part of the submission.
> 
> I'm slightly uncomfortable with having my Signed-off-by as the first
> one when I did not write the changelog myself, so I'd prefer if
> you just add my Acked-by once I provide that. If that doesn't
> work for you, let's follow up in private to sort it out.
> 
Ok. I will remove it.

> 	Arnd
> 


-- 
Murali Karicheri
Linux Kernel, Keystone

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#1338352

On Friday 19 February 2016 10:48:30 Murali Karicheri wrote:
> On 02/19/2016 09:41 AM, Arnd Bergmann wrote:
> > On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:
> >> From: Arnd Bergmann <arnd@arndb.de>
> >>
> >> The commit 899077791403 ("netcp: try to reduce type confusion in
> >> descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
> >> get/set_pad_info() functionality.
> >>
> >> The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
> >> store DMA/MEM buffer pointer and buffer size respectively. And in both
> >> cases for Keystone 2 the pointer type size is 32 bit regardless of
> >> LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
> >> is not expected to be defined.
> >>
> >>                      !LAPE   LPAE
> >> sizeof(void*)                32bit   32bit
> >> sizeof(dma_addr_t)   32bit   32bit
> >> sizeof(phys_addr_t)  32bit   64bit
> > 
> > As this was never relevant or true, I don't think it needs to be
> > mentioned here, it just confuses things. Please just assume that
> > dma_addr_t can be 64-bit wide, but will only contain 32-bit
> > numbers on keystone.
> > 
> 
> I can remove this from the commit description and re-send.

Ok

> >> Unfortunately, above commit changed buffer's pointers save/restore
> >> code (get/set_pad_info()) and added intermediate conversation to u64
> >> which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
> >> crash in RX/TX path due to "Unable to handle kernel NULL pointer"
> >> exception. This issue was reported and discussed in [1].
> > 
> > Have you been able to figure out why it actually broke? I'd still
> > like to know.
> > 
> As Grygorii is out of office until Monday, I would like to step in.
> I will take some time today to try review the reverted changes for
> failure reason and get back. But as you have agreed in the discussion
> at https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
> Can we fix the regression by applying this patch and rest of the series
> if it looks good? If I need to separate this from rest of the series,
> let me know and I can take care of that.

Yes, sounds fine.

> >> Hence, fix it by partially reverting above commit and restoring
> >> get/set_pad_info() functionality as it was before.
> >>
> >> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
> >> Cc: Wingman Kwok <w-kwok2@ti.com>
> >> Cc: Mugunthan V N <mugunthanvnm@ti.com>
> >> CC: David Laight <David.Laight@ACULAB.COM>
> >> Reported-by: Franklin S Cooper Jr <fcooper@ti.com>
> >> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> >> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
> > 
> > I don't think I sent this patch with a 'Signed-off-by', did I?
> > (I could be misremembering that).
> > 
> 
> I think you had agreed based on what I read at
> https://www.mail-archive.com/netdev@vger.kernel.org/msg96311.html
> 
> reproduced below for your convenience.
> =============================================================================
> 
> > What I could do now is update your/my patch as i mentioned in [1]
> > and re-send it at the weekend (with your authorship and my signoff).
> > Do you agree?
> > 
> > 
> > [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95831.html
> 
> Yes, let's do that in the meantime. I can also make sure that that
> the driver doesn't build on 64-bit, just in case.
> =============================================================================
> 
> Hope I can keep your sign-off when I re-send this. Please confirm.

The most important part here is that you don't add a "Signed-off-by"
tag unless it was provided by that person as part of the submission.

I'm slightly uncomfortable with having my Signed-off-by as the first
one when I did not write the changelog myself, so I'd prefer if
you just add my Acked-by once I provide that. If that doesn't
work for you, let's follow up in private to sort it out.

	Arnd

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#1338395 — Re: [PATCH v1 1/4] net: ti: netcp: restore get/set_pad_info() functionality

On 02/19/2016 09:41 AM, Arnd Bergmann wrote:
> On Thursday 18 February 2016 14:46:14 Murali Karicheri wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>>
>> The commit 899077791403 ("netcp: try to reduce type confusion in
>> descriptors") introduces a regression in Kernel 4.5-rc1 and it breaks
>> get/set_pad_info() functionality.
>>
>> The TI NETCP driver uses pad0 and pad1 fields of knav_dma_desc to
>> store DMA/MEM buffer pointer and buffer size respectively. And in both
>> cases for Keystone 2 the pointer type size is 32 bit regardless of
>> LAPE enabled or not, because CONFIG_ARCH_DMA_ADDR_T_64BIT originally
>> is not expected to be defined.
>>
>> 			!LAPE	LPAE
>> sizeof(void*)		32bit	32bit
>> sizeof(dma_addr_t) 	32bit	32bit
>> sizeof(phys_addr_t) 	32bit	64bit
> 
> As this was never relevant or true, I don't think it needs to be
> mentioned here, it just confuses things. Please just assume that
> dma_addr_t can be 64-bit wide, but will only contain 32-bit
> numbers on keystone.
> 
>> Unfortunately, above commit changed buffer's pointers save/restore
>> code (get/set_pad_info()) and added intermediate conversation to u64
>> which works incorrectly on 32bit Keystone 2 and causes TI NETCP driver
>> crash in RX/TX path due to "Unable to handle kernel NULL pointer"
>> exception. This issue was reported and discussed in [1].
> 
> Have you been able to figure out why it actually broke? I'd still
> like to know.
> 
I have just send v2. I will investigate your original patch that added
regression this afternoon and respond with my observation as soon as
my investigation is complete. I assume, you are trying to make the change
such that the virtual pointers stored in sw_data/pad works across
32bit and 64bit machine, right? 

Murali

>> Hence, fix it by partially reverting above commit and restoring
>> get/set_pad_info() functionality as it was before.
>>
>> [1] https://www.mail-archive.com/netdev@vger.kernel.org/msg95361.html
>> Cc: Wingman Kwok <w-kwok2@ti.com>
>> Cc: Mugunthan V N <mugunthanvnm@ti.com>
>> CC: David Laight <David.Laight@ACULAB.COM>
>> Reported-by: Franklin S Cooper Jr <fcooper@ti.com>
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
>> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
> 
> I don't think I sent this patch with a 'Signed-off-by', did I?
> (I could be misremembering that).
> 
> 	Arnd
> 


-- 
Murali Karicheri
Linux Kernel, Keystone

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#1338460

On Friday 19 February 2016 13:01:59 Murali Karicheri wrote:
> > 
> I have just send v2. I will investigate your original patch that added
> regression this afternoon and respond with my observation as soon as
> my investigation is complete.

Thanks.

> I assume, you are trying to make the change
> such that the virtual pointers stored in sw_data/pad works across
> 32bit and 64bit machine, right? 

Yes, that was the idea. The way I intended it, pointers were supposed
to always get stored in a pair of swdata fields and take up 64 bits,
independent of the architecture.

	Arnd

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