3123227228
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
#ifndef __LINUX_CPU_RMAP_H
|
|
#define __LINUX_CPU_RMAP_H
|
|
|
|
/*
|
|
* cpu_rmap.c: CPU affinity reverse-map support
|
|
* Copyright 2011 Solarflare Communications Inc.
|
|
*/
|
|
|
|
#include <linux/cpumask.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/kref.h>
|
|
|
|
/**
|
|
* struct cpu_rmap - CPU affinity reverse-map
|
|
* @refcount: kref for object
|
|
* @size: Number of objects to be reverse-mapped
|
|
* @used: Number of objects added
|
|
* @obj: Pointer to array of object pointers
|
|
* @near: For each CPU, the index and distance to the nearest object,
|
|
* based on affinity masks
|
|
*/
|
|
struct cpu_rmap {
|
|
struct kref refcount;
|
|
u16 size, used;
|
|
void **obj;
|
|
struct {
|
|
u16 index;
|
|
u16 dist;
|
|
} near[];
|
|
};
|
|
#define CPU_RMAP_DIST_INF 0xffff
|
|
|
|
extern struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags);
|
|
extern int cpu_rmap_put(struct cpu_rmap *rmap);
|
|
|
|
extern int cpu_rmap_add(struct cpu_rmap *rmap, void *obj);
|
|
extern int cpu_rmap_update(struct cpu_rmap *rmap, u16 index,
|
|
const struct cpumask *affinity);
|
|
|
|
static inline u16 cpu_rmap_lookup_index(struct cpu_rmap *rmap, unsigned int cpu)
|
|
{
|
|
return rmap->near[cpu].index;
|
|
}
|
|
|
|
static inline void *cpu_rmap_lookup_obj(struct cpu_rmap *rmap, unsigned int cpu)
|
|
{
|
|
return rmap->obj[rmap->near[cpu].index];
|
|
}
|
|
|
|
/**
|
|
* alloc_irq_cpu_rmap - allocate CPU affinity reverse-map for IRQs
|
|
* @size: Number of objects to be mapped
|
|
*
|
|
* Must be called in process context.
|
|
*/
|
|
static inline struct cpu_rmap *alloc_irq_cpu_rmap(unsigned int size)
|
|
{
|
|
return alloc_cpu_rmap(size, GFP_KERNEL);
|
|
}
|
|
extern void free_irq_cpu_rmap(struct cpu_rmap *rmap);
|
|
|
|
extern int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq);
|
|
|
|
#endif /* __LINUX_CPU_RMAP_H */
|