dpll: fix xa_alloc_cyclic() error handling

In case of returning 1 from xa_alloc_cyclic() (wrapping) ERR_PTR(1) will
be returned, which will cause IS_ERR() to be false. Which can lead to
dereference not allocated pointer (pin).

Fix it by checking if err is lower than zero.

This wasn't found in real usecase, only noticed. Credit to Pierre.

Fixes: 97f265e ("dpll: allocate pin ids in cycle")
Signed-off-by: Michal Swiatkowski <[email protected]>
Reviewed-by: Vadim Fedorenko <[email protected]>
Reviewed-by: Arkadiusz Kubalewski <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Michal Swiatkowski

drivers/dpll/dpll_core.c

@@ -505,7 +505,7 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct module *module,
 	xa_init_flags(&pin->parent_refs, XA_FLAGS_ALLOC);
 	ret = xa_alloc_cyclic(&dpll_pin_xa, &pin->id, pin, xa_limit_32b,
 			      &dpll_pin_xa_id, GFP_KERNEL);
-	if (ret)
+	if (ret < 0)
 		goto err_xa_alloc;
 	return pin;
 err_xa_alloc: