On Mon, Feb 15, 2021 at 6:52 PM Hans de Goede [off-list ref] wrote:

Hi,

On 12/26/20 3:28 PM, Hans de Goede wrote:

quoted

Hi All,

On one of my machines I noticed the following errors being logged:

[   52.892807] i2c i2c-0: adapter quirk: no zero length (addr 0x0078, size 0, read)
[   52.893037] i2c i2c-0: i2c read 0 bytes from client@0x78 starting at reg 0x0 failed, error: -95

The second line is coming from the Linux I2C ACPI OpRegion handling and
after a bunch of debugging I've found out that there is a rather obvious
(once you see it) and nasty race condition in the handling of I2C and GPIO
opregions in acpi_ev_address_space_dispatch(). See the first patch in this
series (the second patch is a follow-up cleanup patch removing some code
duplication).

TBH I'm surprised that this issue has gone unnoticed as long as it has,
but I guess that it mostly leads to unreproducable sporadic problems
making it hard to debug and I got lucky that I had a machine where the
race seems to trigger about once every 20 seconds.

I know that ACPICA patches are normally merged through the ACPICA upstream
but given that this is a serious bug, I believe that in this case it might
be best to add the fix directly to Linux and then port it to ACPICA from
there.

ping ?

This was submitted 2 full months ago; and despite this:

1. Fixing a serious bug in ACPICA
2. The fix being pretty simple (and AFAICT obviously correct)

This is still awaiting review upstream:
https://github.com/acpica/acpica/pull/658

I must say that it feels to me that the upstream ACPICA process is broken here.

I submitted a pull-req for this, as requested and after that there has
been zero progress.

The pull-req even has a 26 day old "this looks good to me" comment from Erik,
followed by silence... ?

Rafael, can you please consider just directly picking these 2 fixes into
your acpi branch, so that we can get this nasty race condition fixed ?

I will do that later this week, thanks!