NACK/CMT: [SRU][F:linux-bluefield][PATCH v1 0/1] UBUNTU: SAUCE: tmfifo: Fix a memory barrier issue

[Liming Sun]

Thanks for the comments! I resent patch v3 in its own thread.

- Liming

> -----Original Message-----
> From: Kelsey Skunberg <kelsey.skunberg at canonical.com>
> Sent: Thursday, May 6, 2021 12:57 AM
> To: Liming Sun <limings at nvidia.com>
> Cc: kernel-team at lists.ubuntu.com
> Subject: NACK/CMT: [SRU][F:linux-bluefield][PATCH v1 0/1] UBUNTU:
> SAUCE: tmfifo: Fix a memory barrier issue
> 
> Hi Liming,
> 
> Please also send v2 as its own thread. Same response as I left on your
> other patch set "UBUNTU: SAUCE: platform/mellanox: Add ctrl message and
> MAC configuration".
> 
> Thank you!
> 
> -Kelsey
> 
> On 2021-05-05 12:58:27 , Liming Sun wrote:
> > BugLink:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs
> .launchpad.net%2Fbugs%2F1927262&data=04%7C01%7Climings%40nvid
> ia.com%7C9301bd3977774c0402b108d9104b62fd%7C43083d15727340c1b7db3
> 9efd9ccc17a%7C0%7C0%7C637558738235771349%7CUnknown%7CTWFpbGZs
> b3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn
> 0%3D%7C1000&sdata=Zny7l5%2F88zWYPrPWJgKT0wGqMc8c%2BfmV%
> 2Br6GhrGX0vk%3D&reserved=0
> >
> > SRU Justification:
> >
> > [Impact]
> >
> > * The virtio framework uses wmb() when updating avail->idx. It guarantees
> >   the write order, but not necessarily loading order for the code accessing
> >   the memory. So potentially it could cause traffic stuck which has been
> >   observed in the field.
> >
> > [Fix]
> > * This commit adds a load barrier after reading the avail->idx to make sure
> >   all the data in the descriptor is visible. It also adds a barrier when
> >   returning the packet to virtio framework to make sure read/writes are
> >   visible to the virtio code.
> >
> > [Test Case]
> > * Just normal test. This change doesn't affect any functionality.
> >
> > [Regression Potential]
> >
> > * This version of the driver was tested by QA/verification for a while so no
> >   known regression at the moment.
> >
> > --
> > kernel-team mailing list
> > kernel-team at lists.ubuntu.com
> >
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> =0