[RFC]: scsi_error: interruptible scsi_block_when_processing_errors()

[Douglas Gilbert <dgilbert@interlog.com>]

The existing scsi_block_when_processing_errors() function
in scsi_error.c does a non-interruptible wait on the
host_wait work queue. That call is made from many places
in the scsi subsystem ULDs (e.g. the sg driver).

In many cases (e.g. sg_open()) there is a direct path
back to the user space. So why hang open(sg_device) calls
(that don't use O_NONBLOCK) in an non-interruptible call
for what might be a long time.

Apart from signal indications, such a non-interruptible
version of scsi_block_when_processing_errors() could return
useful (possibly negated) errno_s, for example indicating
the device in question had been detached or timed out
(possibly because the HBA was being reset).

Thoughts?

Doug Gilbert