> -----Original Message----- > From: Hans de Goede <hdegoede@xxxxxxxxxx> > Sent: Saturday, December 26, 2020 6:28 AM > To: Rafael J . Wysocki <rjw@xxxxxxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx>; > Moore, Robert <robert.moore@xxxxxxxxx>; Kaneda, Erik > <erik.kaneda@xxxxxxxxx> > Cc: Hans de Goede <hdegoede@xxxxxxxxxx>; linux-acpi@xxxxxxxxxxxxxxx; > devel@xxxxxxxxxx > Subject: [PATCH 0/2] ACPICA: Fix a race in GenericSerialBus (I2C) and GPIO > handling > > 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. Thanks for this changeset! I'm taking a look right now Erik > > Regards, > > Hans
