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    SubjectRe: [PATCH 0/3] PCI: Rework config space locking, add INTx masking services
    On 2011-10-06 17:48, Jesse Barnes wrote:
    > On Mon, 12 Sep 2011 18:54:01 +0200
    > Jan Kiszka <> wrote:
    >> This series tries to heal the currently broken locking scheme around PCI
    >> config space accesses.
    >> We have an interface lock out access via sysfs, but that service wrongly
    >> assumes it is only called by one instance at a time for some device. So
    >> two loops doing
    >> echo 1 > /sys/bus/pci/devices/<some-device>/reset
    >> in parallel will trigger a kernel BUG at the moment.
    >> Besides synchronizing with user space, we also need to manage config
    >> space access of generic PCI drivers. They need to mask legacy interrupt
    >> lines while the specific driver runs in user space or a guest OS.
    >> The approach taken here is provide mutex-like locking for general
    >> access - which still requires a special mechanism due to requirements of
    >> the IBM Power RAID SCSI driver. Furthermore, INTx masking is now
    >> available via the PCI core and synchronized via the internal pci_lock.
    >> Not sure who may want to take this, so I'm CC'ing broadly.
    > ISTR a bunch of discussion about this (just back from lots of work
    > travel and vacation, sorry I missed most of it).
    > Is this the agreed upon way of handling it? If so, can I get some
    > Reviewed/Acked-bys from people?

    I hope this is acceptable. These changes are required for further
    improvements of the KVM device assignment support (INTx sharing). So I
    would appreciate any ack or whatever feedback as well.


    Siemens AG, Corporate Technology, CT T DE IT 1
    Corporate Competence Center Embedded Linux

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