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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2019-07-01 23:03:29 +0200 |
|---|---|---|
| committer | Matthew Wilcox (Oracle) <willy@infradead.org> | 2019-07-01 23:11:16 +0200 |
| commit | 91abab83839aa2eba073e4a63c729832fdb27ea1 (patch) | |
| tree | 3a083d68dc7d4fdca445313c74852943fafbf7f4 /lib | |
| parent | Linux 5.2-rc7 (diff) | |
| download | linux-91abab83839aa2eba073e4a63c729832fdb27ea1.tar.xz linux-91abab83839aa2eba073e4a63c729832fdb27ea1.zip | |
XArray: Fix xas_next() with a single entry at 0
If there is only a single entry at 0, the first time we call xas_next(),
we return the entry. Unfortunately, all subsequent times we call
xas_next(), we also return the entry at 0 instead of noticing that the
xa_index is now greater than zero. This broke find_get_pages_contig().
Fixes: 64d3e9a9e0cc ("xarray: Step through an XArray")
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/test_xarray.c | 24 | ||||
| -rw-r--r-- | lib/xarray.c | 4 |
2 files changed, 28 insertions, 0 deletions
diff --git a/lib/test_xarray.c b/lib/test_xarray.c index 9d631a7b6a70..7df4f7f395bf 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -1110,6 +1110,28 @@ static noinline void check_find_entry(struct xarray *xa) XA_BUG_ON(xa, !xa_empty(xa)); } +static noinline void check_move_tiny(struct xarray *xa) +{ + XA_STATE(xas, xa, 0); + + XA_BUG_ON(xa, !xa_empty(xa)); + rcu_read_lock(); + XA_BUG_ON(xa, xas_next(&xas) != NULL); + XA_BUG_ON(xa, xas_next(&xas) != NULL); + rcu_read_unlock(); + xa_store_index(xa, 0, GFP_KERNEL); + rcu_read_lock(); + xas_set(&xas, 0); + XA_BUG_ON(xa, xas_next(&xas) != xa_mk_index(0)); + XA_BUG_ON(xa, xas_next(&xas) != NULL); + xas_set(&xas, 0); + XA_BUG_ON(xa, xas_prev(&xas) != xa_mk_index(0)); + XA_BUG_ON(xa, xas_prev(&xas) != NULL); + rcu_read_unlock(); + xa_erase_index(xa, 0); + XA_BUG_ON(xa, !xa_empty(xa)); +} + static noinline void check_move_small(struct xarray *xa, unsigned long idx) { XA_STATE(xas, xa, 0); @@ -1217,6 +1239,8 @@ static noinline void check_move(struct xarray *xa) xa_destroy(xa); + check_move_tiny(xa); + for (i = 0; i < 16; i++) check_move_small(xa, 1UL << i); diff --git a/lib/xarray.c b/lib/xarray.c index 446b956c9188..1237c213f52b 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -994,6 +994,8 @@ void *__xas_prev(struct xa_state *xas) if (!xas_frozen(xas->xa_node)) xas->xa_index--; + if (!xas->xa_node) + return set_bounds(xas); if (xas_not_node(xas->xa_node)) return xas_load(xas); @@ -1031,6 +1033,8 @@ void *__xas_next(struct xa_state *xas) if (!xas_frozen(xas->xa_node)) xas->xa_index++; + if (!xas->xa_node) + return set_bounds(xas); if (xas_not_node(xas->xa_node)) return xas_load(xas); |