Documentation: RCU: adopt new coding style of type-aware kmalloc-family

Update Documentation/RCU/* to reflect new type-aware kmalloc-family
as suggested in commit 2932ba8d9c ("slab: Introduce kmalloc_obj()
and family")

ptr = kmalloc(sizeof(*ptr), gfp);
 -> ptr = kmalloc_obj(*ptr, gfp);

Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: SeongJae Park <sj@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260429072320.310817-2-manuelebner@mailbox.org>

Documentation/RCU/Design/Requirements/Requirements.rst

@@ -206,7 +206,7 @@ non-\ ``NULL``, locklessly accessing the ``->a`` and ``->b`` fields.
 
        1 bool add_gp_buggy(int a, int b)
        2 {
-       3   p = kmalloc(sizeof(*p), GFP_KERNEL);
+       3   p = kmalloc_obj(*p);
        4   if (!p)
        5     return -ENOMEM;
        6   spin_lock(&gp_lock);
@@ -228,7 +228,7 @@ their rights to reorder this code as follows:
 
        1 bool add_gp_buggy_optimized(int a, int b)
        2 {
-       3   p = kmalloc(sizeof(*p), GFP_KERNEL);
+       3   p = kmalloc_obj(*p);
        4   if (!p)
        5     return -ENOMEM;
        6   spin_lock(&gp_lock);
@@ -264,7 +264,7 @@ shows an example of insertion:
 
        1 bool add_gp(int a, int b)
        2 {
-       3   p = kmalloc(sizeof(*p), GFP_KERNEL);
+       3   p = kmalloc_obj(*p);
        4   if (!p)
        5     return -ENOMEM;
        6   spin_lock(&gp_lock);

Documentation/RCU/listRCU.rst

@@ -276,7 +276,7 @@ The RCU version of audit_upd_rule() is as follows::
 
 		list_for_each_entry(e, list, list) {
 			if (!audit_compare_rule(rule, &e->rule)) {
-				ne = kmalloc(sizeof(*entry), GFP_ATOMIC);
+				ne = kmalloc_obj(*entry, GFP_ATOMIC);
 				if (ne == NULL)
 					return -ENOMEM;
 				audit_copy_rule(&ne->rule, &e->rule);

Documentation/RCU/whatisRCU.rst

@@ -468,7 +468,7 @@ uses of RCU may be found in listRCU.rst and NMI-RCU.rst.
 		struct foo *new_fp;
 		struct foo *old_fp;
 
-		new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL);
+		new_fp = kmalloc_obj(*new_fp);
 		spin_lock(&foo_mutex);
 		old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex));
 		*new_fp = *old_fp;
@@ -570,7 +570,7 @@ The foo_update_a() function might then be written as follows::
 		struct foo *new_fp;
 		struct foo *old_fp;
 
-		new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL);
+		new_fp = kmalloc_obj(*new_fp);
 		spin_lock(&foo_mutex);
 		old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex));
 		*new_fp = *old_fp;