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XArray: Fix xas_pause at ULONG_MAX

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If we were unlucky enough to call xas_pause() when the index was at
ULONG_MAX (or a multi-slot entry which ends at ULONG_MAX), we would
wrap the index back around to 0 and restart the iteration from the
beginning.  Use the XAS_BOUNDS state to indicate that we should just
stop the iteration.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
This commit is contained in:
Matthew Wilcox (Oracle)
2019-11-07 22:49:11 -05:00
parent 0058b0a506
commit 82a22311b7
2 changed files with 27 additions and 3 deletions
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8
lib/xarray.c
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@@ -967,6 +967,7 @@ void xas_pause(struct xa_state *xas)
if (xas_invalid(xas))
return;
xas->xa_node = XAS_RESTART;
if (node) {
unsigned int offset = xas->xa_offset;
while (++offset < XA_CHUNK_SIZE) {
@@ -974,10 +975,11 @@ void xas_pause(struct xa_state *xas)
break;
}
xas->xa_index += (offset - xas->xa_offset) << node->shift;
if (xas->xa_index == 0)
xas->xa_node = XAS_BOUNDS;
} else {
xas->xa_index++;
}
xas->xa_node = XAS_RESTART;
}
EXPORT_SYMBOL_GPL(xas_pause);
@@ -1079,13 +1081,13 @@ void *xas_find(struct xa_state *xas, unsigned long max)
{
void *entry;
if (xas_error(xas))
if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
return NULL;
if (!xas->xa_node) {
xas->xa_index = 1;
return set_bounds(xas);
} else if (xas_top(xas->xa_node)) {
} else if (xas->xa_node == XAS_RESTART) {
entry = xas_load(xas);
if (entry || xas_not_node(xas->xa_node))
return entry;