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Bug #14798

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scsi_dmafree (x86 only) in sd.c unwise

Added by Garrett D'Amore 3 months ago.

Status:
New
Priority:
Normal
Category:
-
Start date:
Due date:
% Done:

0%

Estimated time:
Difficulty:
Expert
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Gerrit CR:
External Bug:

Description

The sd.c driver has a bunch of complexity to try to help SCSI VHCI avoid reallocating a SCSI packet in the face of a path failure, so that the command can be reissued on an alternate path.

This is almost certainly a well meaning, but completely misguided, attempt to improve performance on a failure path.

Failures here should be rare. And the cost of freeing and reallocating DMA is likely the bulk of the logic. Also, the logic that tries to make assumptions here is brittle, and would almost certainly need to be updated to support other architectures.

The best thing to do is just deal with the failure by reallocating the packet in VHCI, and not trying to play this crazy games.

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