number modulo the given alignment.
To do this the function extent_alloc_subregion() takes an additional `skew'
parameter. For compatibility's sake, this function has been renamed to
extent_alloc_subregion1().
(1): "substart == ex->ex_end" and "subend == ex->ex_start"
are completely legal parameters for extent_alloc_subregion()
(2): "(subend - substart) + 1" can cause an overflow if the whole
numeric range is covered by the extent.
Submitted by Matthias Drochner <drochner@zelz26.zel.kfa-juelich.de>
in PR #3119.
If not compiled with -D_KERNEL, include different includes and
do so macro magic so that this will fit sanely into test harnesses.
When used in user-land, this should be compiled with -D_EXTENT_TESTING.
Bug fixes:
(extent_insert_and_optimize) You can't do things like:
LIST_REMOVE(elem->...le_next, ...);
free(elem->...le_next, ...);
They just don't work (and will corrupt your list and/or malloc free list).
(extent_alloc_region_descriptor) Unless you wait, malloc can fail.
Don't accidentally deref a potentially-NULL pointer.
- Rename EX_NOBLOB to EX_NOCOALESCE; it's much more descriptive of
what's going on.
- In extent_free_region_descriptor(), if we're a fixed extent,
freeing a dynamically allocated region descriptor, and someone
is waiting on the freelist, let the waiter have it, rather than
free'ing it back to the system.
- Use ALIGN(), rather than our homegrown EXTENT_ALIGN(), when dealing
with map overhead. Privatize the EXTENT_ALIGN() macro; there's no need
to export it.
- Implement EX_BOUNDZERO flag. This changes the boundary line policy in
extent_alloc() and extent_alloc_subregion(); boundary lines are
computed relative to 0, rather then the start of the extent.
- Fix a nasty race between multiple participants doing region and
descriptor allocation.
- Add a new flag to specify that it's ok to wait for space in the
extent: EX_WAITSPACE.
- Blow away an unnecessary splhigh()/splx().
- Put a bunch of sanity code inside #ifdef DIAGNOSTIC/#endif.
Understands allocation aligment and boundary restrictions, "specific region"
allocations, and suballocations. Capable of statically or dynamically
allocating map overhead.
Many thanks to Matthias Drochner for running the code for me, and sending
me bug fixes, optimizations, and suggestions. Also, many thanks to
Chris Demetriou for his extremely helpful suggestions.
XXX No manual page yet. One is forthcoming, as soon as I can scare up
the time to write one. This has been sitting on my plate for quite a
while, and several projects are waiting for it. Time to move on.
