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    SubjectRe: SCSI host numbers?
    Itai Nahshon writes:
    > On Wednesday 02 January 2002 01:32 pm, Alan Cox wrote:
    > > > Under some scenarios Linux assigns the same
    > > > host_no to more than one scsi device.
    > > >
    > > > Can someone tell me what is the intended behavior?
    > >
    > > A number should never be reissued.
    > >
    > > > The problem is that a newly registered device gets
    > > > its host_no from max_scsi_host. max_scsi_host is
    > > > decremented when a device driver is unregistered
    > > > (see drivers/scsi/host.c) allowing a second new
    > > > host to reuse the same host_no.
    > >
    > > I guess it needs to either only decrement the count if we are the highest
    >
    > I'll argue that it should never decrement. The host that was just
    > unregisrtered already has its host_id reserved and if we decrement,
    > this number will be reasigned to the next new scsi host.
    >
    > Unless if the code for reservation that causes the conflicts
    > is removed (but I guess it has a reason).
    >
    > > one (trivial hack) or scan for a free number/keep a free bitmap. The devfs
    > > code has a handy little unique_id function for that
    >
    > That would not solve it. The problem is that one piece of code
    > tries to allocate unique numbers (and get them back to the pool
    > when they are not in use), another piece of code remembers the
    > old number that a scsi host had and whan it re-registers gives
    > it back its old host_no regardless if this number was re-assigned
    > to a new host.

    Where exactly is the host_id for an unregistered host being
    remembered?

    Regards,

    Richard....
    Permanent: rgooch@atnf.csiro.au
    Current: rgooch@ras.ucalgary.ca
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