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Sometimes, when asked to return region A..C, we'd return A+N..C+N

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instead of failing.

When looking for a region to allocate, we used to check to see if the
start address was < end.  In the case where A..B is allocated already,
and one wants to allocate A..C (B < C), then this test would
improperly fail (which means we'd examine that region as a possible
one), and we'd return the region B+1..C+(B-A+1) rather than NULL.
Since C+(B-A+1) is necessarily larger than C (end argument), this is
incorrect behavior for rman_reserve_resource_bound().

The fix is to exclude those regions where r->r_start + count - 1 > end
rather than r->r_start > end.  This bug has been in this code for a
very long time.  I believe that all other tests against end are
correctly done.

This is why sio0 generated a message about interrupts not being
enabled properly for the device.  When fdc had a bug that allocated
from 0x3f7 to 0x3fb, sio0 was then given 0x3fc-0x404 rather than the
0x3f8-0x3ff that it wanted.  Now when fdc has the same bug, sio0 fails
to allocate its ports, which is the proper behavior.  Since the probe
failed, we never saw the messed up resources reported.

I suspect that there are other places in the tree that have weird
looping or other odd work arounds to try to cope with the observed
weirdness this bug can introduce.  These workarounds should be located
and eliminated.

Minor debug write fix to match the above test done as well.

'nice' by: mdodd
Sponsored by: timing solutions (http://www.timing.com/)
This commit is contained in:
Warner Losh 2005-03-15 20:28:51 +00:00
parent a33ab77447
commit 358fef538f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=143665
1 changed files with 3 additions and 2 deletions
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5
sys/kern/subr_rman.c
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@ -217,8 +217,9 @@ rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end,
*/
for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
if (s->r_start > end) {
DPRINTF(("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end));
if (s->r_start + count - 1 > end) {
DPRINTF(("s->r_start (%#lx) + count - 1> end (%#lx)\n",
s->r_start, end));
break;
}
if (s->r_flags & RF_ALLOCATED) {