Wanted: spl()ing checkers
Arthur David Olson
ado at elsie.UUCP
Tue Oct 8 01:00:42 AEST 1985
The 4.2bsd version of the kernel function "bflush" calls "spl6",
goes through some gyrations, and eventually may call one of the disk "strategy"
functions. One of these in particular, "hpstrategy", calls "spl5".
Now it seems to me that theoretically the spl5 call when things are chugging
along at priority level 6 is a no-no--although in this case there doesn't seem
to be any bad effect in practice.
And so some questions to all you wizards:
1. Should "bflush" actually be doing a "spl5" call?
2. Should "hpstrategy" actually be doing a "spl6" call?
3. Should "bflush" be doing a "splx(s)" call (to restore the processor
level to its entry value) before calling the disk strategy function?
4. Should spl4, spl5, spl6, and spl7 check to ensure that the priority
level is being raised before changing the priority level?
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