XArray: Mark xa_insert and xa_reserve as must_check

If the user doesn't care about the return value from xa_insert(), then
they should be using xa_store() instead.  The point of xa_reserve() is
to get the return value early before taking another lock, so this should
also be __must_check.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

include/linux/xarray.h

@@ -497,12 +497,13 @@ void *__xa_erase(struct xarray *, unsigned long index);
 void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
 void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
 		void *entry, gfp_t);
-int __xa_insert(struct xarray *, unsigned long index, void *entry, gfp_t);
+int __must_check __xa_insert(struct xarray *, unsigned long index,
+		void *entry, gfp_t);
 int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
 		struct xa_limit, gfp_t);
 int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
 		struct xa_limit, u32 *next, gfp_t);
-int __xa_reserve(struct xarray *, unsigned long index, gfp_t);
+int __must_check __xa_reserve(struct xarray *, unsigned long index, gfp_t);
 void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
 void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
 
@@ -704,8 +705,8 @@ static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
  * -ENOMEM if memory could not be allocated.
  */
-static inline int xa_insert(struct xarray *xa, unsigned long index,
-		void *entry, gfp_t gfp)
+static inline int __must_check xa_insert(struct xarray *xa,
+		unsigned long index, void *entry, gfp_t gfp)
 {
 	int err;
 
@@ -733,8 +734,8 @@ static inline int xa_insert(struct xarray *xa, unsigned long index,
  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
  * -ENOMEM if memory could not be allocated.
  */
-static inline int xa_insert_bh(struct xarray *xa, unsigned long index,
-		void *entry, gfp_t gfp)
+static inline int __must_check xa_insert_bh(struct xarray *xa,
+		unsigned long index, void *entry, gfp_t gfp)
 {
 	int err;
 
@@ -762,8 +763,8 @@ static inline int xa_insert_bh(struct xarray *xa, unsigned long index,
  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
  * -ENOMEM if memory could not be allocated.
  */
-static inline int xa_insert_irq(struct xarray *xa, unsigned long index,
-		void *entry, gfp_t gfp)
+static inline int __must_check xa_insert_irq(struct xarray *xa,
+		unsigned long index, void *entry, gfp_t gfp)
 {
 	int err;
 
@@ -978,7 +979,7 @@ static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
  * May sleep if the @gfp flags permit.
  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
  */
-static inline
+static inline __must_check
 int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
 {
 	int ret;
@@ -1002,7 +1003,7 @@ int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
  * disabling softirqs.
  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
  */
-static inline
+static inline __must_check
 int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
 {
 	int ret;
@@ -1026,7 +1027,7 @@ int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
  * disabling interrupts.
  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
  */
-static inline
+static inline __must_check
 int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
 {
 	int ret;

lib/test_xarray.c

@@ -364,21 +364,21 @@ static noinline void check_reserve(struct xarray *xa)
 
 	/* An array with a reserved entry is not empty */
 	XA_BUG_ON(xa, !xa_empty(xa));
-	xa_reserve(xa, 12345678, GFP_KERNEL);
+	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
 	XA_BUG_ON(xa, xa_empty(xa));
 	XA_BUG_ON(xa, xa_load(xa, 12345678));
 	xa_release(xa, 12345678);
 	XA_BUG_ON(xa, !xa_empty(xa));
 
 	/* Releasing a used entry does nothing */
-	xa_reserve(xa, 12345678, GFP_KERNEL);
+	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
 	XA_BUG_ON(xa, xa_store_index(xa, 12345678, GFP_NOWAIT) != NULL);
 	xa_release(xa, 12345678);
 	xa_erase_index(xa, 12345678);
 	XA_BUG_ON(xa, !xa_empty(xa));
 
 	/* cmpxchg sees a reserved entry as NULL */
-	xa_reserve(xa, 12345678, GFP_KERNEL);
+	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
 	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, NULL, xa_mk_value(12345678),
 				GFP_NOWAIT) != NULL);
 	xa_release(xa, 12345678);
@@ -386,7 +386,7 @@ static noinline void check_reserve(struct xarray *xa)
 	XA_BUG_ON(xa, !xa_empty(xa));
 
 	/* But xa_insert does not */
-	xa_reserve(xa, 12345678, GFP_KERNEL);
+	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
 	XA_BUG_ON(xa, xa_insert(xa, 12345678, xa_mk_value(12345678), 0) !=
 			-EBUSY);
 	XA_BUG_ON(xa, xa_empty(xa));
@@ -395,7 +395,7 @@ static noinline void check_reserve(struct xarray *xa)
 
 	/* Can iterate through a reserved entry */
 	xa_store_index(xa, 5, GFP_KERNEL);
-	xa_reserve(xa, 6, GFP_KERNEL);
+	XA_BUG_ON(xa, xa_reserve(xa, 6, GFP_KERNEL) != 0);
 	xa_store_index(xa, 7, GFP_KERNEL);
 
 	xa_for_each(xa, index, entry) {