On Thu, Dec 07, 2023 at 02:33:19PM -0500, Liam R. Howlett wrote: > mas_prev() was setting the ma_underflow condition when the limit was > reached and not when the limit was attempting to go lower. This > resulted in the incorrect behaviour on subsequent actions. > > This commit fixes the status setting to only set ma_underflow when the > lower limit is attempted to be decremented, and modifies the testing to > ensure that's the case. > > Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Is this is related to the report[1] I forwarded? If so, please add these tags too: Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> Closes: https://lore.kernel.org/all/CA+G9fYs-j2FYZSFSVZj48mgoM9gQd4-7M2mu2Ez3D1DqDdW2bQ@xxxxxxxxxxxxxx/ [1] Thanks either way! -Kees > --- > > Andrew, > > This should be clean to squash into 7f79fdb1d94d7 ("maple_tree: separate > ma_state node from status.") which is currently in your mm-unstable > branch. > > Thanks, > Liam > > > lib/maple_tree.c | 16 ++++++++++++---- > lib/test_maple_tree.c | 9 +++++++-- > 2 files changed, 19 insertions(+), 6 deletions(-) > > diff --git a/lib/maple_tree.c b/lib/maple_tree.c > index 89f8d21602774..47f2a7a973852 100644 > --- a/lib/maple_tree.c > +++ b/lib/maple_tree.c > @@ -4432,6 +4432,9 @@ static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty) > mas->last = mas->index - 1; > mas->index = mas_safe_min(mas, pivots, mas->offset); > } else { > + if (mas->index <= min) > + goto underflow; > + > if (mas_prev_node(mas, min)) { > mas_rewalk(mas, save_point); > goto retry; > @@ -4452,15 +4455,15 @@ static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty) > if (unlikely(mas_rewalk_if_dead(mas, node, save_point))) > goto retry; > > - if (mas->index <= min) > - mas->status = ma_underflow; > > if (likely(entry)) > return entry; > > if (!empty) { > - if (mas_is_underflow(mas)) > + if (mas->index <= min) { > + mas->status = ma_underflow; > return NULL; > + } > > goto again; > } > @@ -4596,7 +4599,7 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty) > if (unlikely(mas_rewalk_if_dead(mas, node, save_point))) > goto retry; > > - if (pivot >= max) { > + if (pivot >= max) { /* Was at the limit, next will extend beyond */ > mas->status = ma_overflow; > return NULL; > } > @@ -4611,6 +4614,11 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty) > else > mas->last = mas->max; > } else { > + if (mas->last >= max) { > + mas->status = ma_overflow; > + return NULL; > + } > + > if (mas_next_node(mas, node, max)) { > mas_rewalk(mas, save_point); > goto retry; > diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c > index 15fbeb788f3ac..29185ac5c727f 100644 > --- a/lib/test_maple_tree.c > +++ b/lib/test_maple_tree.c > @@ -3294,8 +3294,8 @@ static noinline void __init check_state_handling(struct maple_tree *mt) > MT_BUG_ON(mt, mas.last != 0x1500); > MT_BUG_ON(mt, !mas_is_active(&mas)); > > - /* next:active ->active */ > - entry = mas_next(&mas, ULONG_MAX); > + /* next:active ->active (spanning limit) */ > + entry = mas_next(&mas, 0x2100); > MT_BUG_ON(mt, entry != ptr2); > MT_BUG_ON(mt, mas.index != 0x2000); > MT_BUG_ON(mt, mas.last != 0x2500); > @@ -3360,6 +3360,11 @@ static noinline void __init check_state_handling(struct maple_tree *mt) > MT_BUG_ON(mt, entry != ptr); > MT_BUG_ON(mt, mas.index != 0x1000); > MT_BUG_ON(mt, mas.last != 0x1500); > + MT_BUG_ON(mt, !mas_is_active(&mas)); /* spanning limit */ > + entry = mas_prev(&mas, 0x1200); /* underflow */ > + MT_BUG_ON(mt, entry != NULL); > + MT_BUG_ON(mt, mas.index != 0x1000); > + MT_BUG_ON(mt, mas.last != 0x1500); > MT_BUG_ON(mt, !mas_is_underflow(&mas)); > > /* prev:underflow -> underflow (lower limit) spanning end range */ > -- > 2.40.1 > -- Kees Cook
