mirror of
https://github.com/torvalds/linux.git
synced 2024-11-25 13:41:51 +00:00
ef17f5193e
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")
Reviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200319213839.GA10669@embeddedor.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
70 lines
2.0 KiB
C
70 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* Hardware spinlocks internal header
|
|
*
|
|
* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
|
|
*
|
|
* Contact: Ohad Ben-Cohen <ohad@wizery.com>
|
|
*/
|
|
|
|
#ifndef __HWSPINLOCK_HWSPINLOCK_H
|
|
#define __HWSPINLOCK_HWSPINLOCK_H
|
|
|
|
#include <linux/spinlock.h>
|
|
#include <linux/device.h>
|
|
|
|
struct hwspinlock_device;
|
|
|
|
/**
|
|
* struct hwspinlock_ops - platform-specific hwspinlock handlers
|
|
*
|
|
* @trylock: make a single attempt to take the lock. returns 0 on
|
|
* failure and true on success. may _not_ sleep.
|
|
* @unlock: release the lock. always succeed. may _not_ sleep.
|
|
* @relax: optional, platform-specific relax handler, called by hwspinlock
|
|
* core while spinning on a lock, between two successive
|
|
* invocations of @trylock. may _not_ sleep.
|
|
*/
|
|
struct hwspinlock_ops {
|
|
int (*trylock)(struct hwspinlock *lock);
|
|
void (*unlock)(struct hwspinlock *lock);
|
|
void (*relax)(struct hwspinlock *lock);
|
|
};
|
|
|
|
/**
|
|
* struct hwspinlock - this struct represents a single hwspinlock instance
|
|
* @bank: the hwspinlock_device structure which owns this lock
|
|
* @lock: initialized and used by hwspinlock core
|
|
* @priv: private data, owned by the underlying platform-specific hwspinlock drv
|
|
*/
|
|
struct hwspinlock {
|
|
struct hwspinlock_device *bank;
|
|
spinlock_t lock;
|
|
void *priv;
|
|
};
|
|
|
|
/**
|
|
* struct hwspinlock_device - a device which usually spans numerous hwspinlocks
|
|
* @dev: underlying device, will be used to invoke runtime PM api
|
|
* @ops: platform-specific hwspinlock handlers
|
|
* @base_id: id index of the first lock in this device
|
|
* @num_locks: number of locks in this device
|
|
* @lock: dynamically allocated array of 'struct hwspinlock'
|
|
*/
|
|
struct hwspinlock_device {
|
|
struct device *dev;
|
|
const struct hwspinlock_ops *ops;
|
|
int base_id;
|
|
int num_locks;
|
|
struct hwspinlock lock[];
|
|
};
|
|
|
|
static inline int hwlock_to_id(struct hwspinlock *hwlock)
|
|
{
|
|
int local_id = hwlock - &hwlock->bank->lock[0];
|
|
|
|
return hwlock->bank->base_id + local_id;
|
|
}
|
|
|
|
#endif /* __HWSPINLOCK_HWSPINLOCK_H */
|