Re: [PATCH 2.6.12.5 1/2] lib: allow idr to be used in irq context

[James Bottomley]

On Sun, 2005-08-21 at 08:49 -0700, Luben Tuikov wrote:
> The caller is the aic94xx SAS LLDD.  It uses IDR to generate unique
> task tag for each SCSI task being submitted.  It is then used to lookup
> the task given the task tag, in effect using IDR as a fast lookup table.
> 
> Yes, I'm also not aware of any other users of IDR from mixed process/IRQ
> context or for SCSI Task tag purposes.

Just a minute, that's not what idr was designed for.  It was really
designed for enumerations (like disk) presented to the user.  That's why
using it in IRQ context hasn't been considered.

However, there is an infrastructure in the block layer called the
generic tag infrastructure which was designed precisely for this purpose
and which is designed to operate in IRQ context.

James


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