[dpdk-dev] [PATCH v2] e1000/base: fix multicast setting in VF

[dpdk-dev] [PATCH v2] e1000/base: fix multicast setting in VF

[Yong Wang]

In function e1000_update_mc_addr_list_vf(), "msgbuf[0]" is used prior
to initialization at "msgbuf[0] |= E1000_VF_SET_MULTICAST_OVERFLOW".
And "msgbuf[0]" is overwritten at "msgbuf[0] = E1000_VF_SET_MULTICAST".
Fix it by moving the second line prior to the first one that mentioned
above.

---
v2:
* According to Thomas's suggestion, modify the title.

Signed-off-by: Yong Wang <wang.yong19@zte.com.cn>
---
 drivers/net/e1000/base/e1000_vf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/e1000/base/e1000_vf.c b/drivers/net/e1000/base/e1000_vf.c
index 7845b48..44ab018 100644
--- a/drivers/net/e1000/base/e1000_vf.c
+++ b/drivers/net/e1000/base/e1000_vf.c
@@ -421,12 +421,13 @@ void e1000_update_mc_addr_list_vf(struct e1000_hw *hw,
 
 	DEBUGOUT1("MC Addr Count = %d\n", mc_addr_count);
 
+	msgbuf[0] = E1000_VF_SET_MULTICAST;
+
 	if (mc_addr_count > 30) {
 		msgbuf[0] |= E1000_VF_SET_MULTICAST_OVERFLOW;
 		mc_addr_count = 30;
 	}
 
-	msgbuf[0] = E1000_VF_SET_MULTICAST;
 	msgbuf[0] |= mc_addr_count << E1000_VT_MSGINFO_SHIFT;
 
 	for (i = 0; i < mc_addr_count; i++) {
-- 
1.8.3.1

Re: [dpdk-dev] [PATCH v2] e1000/base: fix multicast setting in VF

[Lu, Wenzhuo]

Hi,

> -----Original Message-----
> From: Yong Wang [mailto:wang.yong19@zte.com.cn]
> Sent: Tuesday, February 21, 2017 5:33 PM
> To: Lu, Wenzhuo
> Cc: dev@dpdk.org; Yong Wang
> Subject: [PATCH v2] e1000/base: fix multicast setting in VF
> 
> In function e1000_update_mc_addr_list_vf(), "msgbuf[0]" is used prior to
> initialization at "msgbuf[0] |= E1000_VF_SET_MULTICAST_OVERFLOW".
> And "msgbuf[0]" is overwritten at "msgbuf[0] = E1000_VF_SET_MULTICAST".
> Fix it by moving the second line prior to the first one that mentioned above.
> 
> ---
> v2:
> * According to Thomas's suggestion, modify the title.
> 
> Signed-off-by: Yong Wang <wang.yong19@zte.com.cn>
Acked-by: Wenzhuo Lu <wenzhuo.lu@intel.com>

Re: [dpdk-dev] [PATCH v2] e1000/base: fix multicast setting in VF

[Ferruh Yigit]

On 2/21/2017 9:33 AM, Yong Wang wrote:
> In function e1000_update_mc_addr_list_vf(), "msgbuf[0]" is used prior
> to initialization at "msgbuf[0] |= E1000_VF_SET_MULTICAST_OVERFLOW".
> And "msgbuf[0]" is overwritten at "msgbuf[0] = E1000_VF_SET_MULTICAST".
> Fix it by moving the second line prior to the first one that mentioned
> above.
> 
> ---
> v2:
> * According to Thomas's suggestion, modify the title.
> 
> Signed-off-by: Yong Wang <wang.yong19@zte.com.cn>

It looks like this fix has a history:

- Defect introduces with initial version

- Fixed with: [1]
  06cf9be95ce1 ("lib: fix uninitialized value")

- Fix reverted with: [2]
  dffbaf7880a8 ("e1000: revert fix for multicast in VF")

- This patch applies same fix again.

Revert does not mention why it has been reverted, this is one of the
samples why commit log matters.

Since code is clearly wrong, I am for getting the fix, but it would be
nice to know why it has been reverted previously.


[1]
commit 06cf9be95ce16b363c4267d2d17e27c2706629ae
Author: Zijie Pan <zijie.pan@6wind.com>
Date:   Thu Dec 6 15:36:51 2012 +0800

    lib: fix uninitialized value

    Fix warning "The left expression of the compound assignment
    is an uninitialized value".

    Signed-off-by: Zijie Pan <zijie.pan@6wind.com>
    Acked-by: Ivan Boule <ivan.boule@6wind.com>
    Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>


[2]
commit dffbaf7880a8d753a4971971256d6c8b90e7ece1
Author: Intel <intel.com>
Date:   Fri Nov 8 03:00:00 2013 +0100

    e1000: revert fix for multicast in VF

    Revert fix from commit 06cf9be95ce16b363c4267d2d17e27c2706629ae.

    Signed-off-by: Intel

Re: [dpdk-dev] [PATCH v2] e1000/base: fix multicast setting in VF

[Ferruh Yigit]

On 2/24/2017 12:32 AM, Lu, Wenzhuo wrote:
> Hi,
> 
>> -----Original Message-----
>> From: Yong Wang [mailto:wang.yong19@zte.com.cn]
>> Sent: Tuesday, February 21, 2017 5:33 PM
>> To: Lu, Wenzhuo
>> Cc: dev@dpdk.org; Yong Wang
>> Subject: [PATCH v2] e1000/base: fix multicast setting in VF
>>
>> In function e1000_update_mc_addr_list_vf(), "msgbuf[0]" is used prior to
>> initialization at "msgbuf[0] |= E1000_VF_SET_MULTICAST_OVERFLOW".
>> And "msgbuf[0]" is overwritten at "msgbuf[0] = E1000_VF_SET_MULTICAST".
>> Fix it by moving the second line prior to the first one that mentioned above.
>>
>> ---
>> v2:
>> * According to Thomas's suggestion, modify the title.
>>
>> Signed-off-by: Yong Wang <wang.yong19@zte.com.cn>
> Acked-by: Wenzhuo Lu <wenzhuo.lu@intel.com>

    net/e1000/base: fix multicast setting in VF

    Fixes: dffbaf7880a8 ("e1000: revert fix for multicast in VF")
    Cc: stable@dpdk.org

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