tracepoint: Use struct_size() in kmalloc()

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct tp_probes {
	...
        struct tracepoint_func probes[0];
};

instance = kmalloc(sizeof(sizeof(struct tp_probes) +
			sizeof(struct tracepoint_func) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kmalloc(struct_size(instance, probes, count) GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 46f2ab1e08a9e9458cc1afc1f804e0b2b173d846..fb9353ed901b428a4222a34c2545eaca29e0e935 100644 (file)
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -68,8 +68,8 @@ struct tp_probes {
 
 static inline void *allocate_probes(int count)
 {
-       struct tp_probes *p  = kmalloc(count * sizeof(struct tracepoint_func)
-                       + sizeof(struct tp_probes), GFP_KERNEL);
+       struct tp_probes *p  = kmalloc(struct_size(p, probes, count),
+                                      GFP_KERNEL);
        return p == NULL ? NULL : p->probes;
 }