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radixtree: Fix crash when non-creator begins iteration over shared tree.

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Previously, if a backend that attached to a shared tree attempted to
start iteration, it resulted in a crash. This commit resolves the
issue by ensuring iter_context is created in RT_ATTACH().

This fix applies only to v17, where radixtree.h was introduced. In the
master branch, this issue was separately resolved by 960013f2a1, which
eliminated the iter_context entirely.

Reviewed-by: John Naylor
Discussion: https://postgr.es/m/CAD21AoBB2U47V=F+wQRB1bERov_of5=BOZGaybjaV8FLQyqG3Q@mail.gmail.com
This commit is contained in:
Masahiko Sawada 2025-02-06 11:35:51 -08:00
parent 32770ea032
commit 9af2b34358
1 changed files with 10 additions and 0 deletions
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10
src/include/lib/radixtree.h
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@ -1902,6 +1902,7 @@ RT_ATTACH(dsa_area *dsa, RT_HANDLE handle)
dsa_pointer control;
tree = (RT_RADIX_TREE *) palloc0(sizeof(RT_RADIX_TREE));
tree->context = CurrentMemoryContext;
/* Find the control object in shared memory */
control = handle;
@ -1910,6 +1911,14 @@ RT_ATTACH(dsa_area *dsa, RT_HANDLE handle)
tree->ctl = (RT_RADIX_TREE_CONTROL *) dsa_get_address(dsa, control);
Assert(tree->ctl->magic == RT_RADIX_TREE_MAGIC);
/*
* Create the iteration context so that the attached backend also can
* begin the iteration.
*/
tree->iter_context = AllocSetContextCreate(CurrentMemoryContext,
RT_STR(RT_PREFIX) "_radix_tree iter context",
ALLOCSET_SMALL_SIZES);
return tree;
}
@ -1917,6 +1926,7 @@ RT_SCOPE void
RT_DETACH(RT_RADIX_TREE * tree)
{
Assert(tree->ctl->magic == RT_RADIX_TREE_MAGIC);
MemoryContextDelete(tree->iter_context);
pfree(tree);
}