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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 */
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/*
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* Hardware spinlocks internal header
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*
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* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
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*
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* Contact: Ohad Ben-Cohen <ohad@wizery.com>
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*/
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#ifndef __HWSPINLOCK_HWSPINLOCK_H
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#define __HWSPINLOCK_HWSPINLOCK_H
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#include <linux/spinlock.h>
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#include <linux/device.h>
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struct hwspinlock_device;
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/**
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* struct hwspinlock_ops - platform-specific hwspinlock handlers
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*
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* @trylock: make a single attempt to take the lock. returns 0 on
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* failure and true on success. may _not_ sleep.
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* @unlock: release the lock. always succeed. may _not_ sleep.
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* @relax: optional, platform-specific relax handler, called by hwspinlock
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* core while spinning on a lock, between two successive
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* invocations of @trylock. may _not_ sleep.
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*/
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struct hwspinlock_ops {
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int (*trylock)(struct hwspinlock *lock);
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void (*unlock)(struct hwspinlock *lock);
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void (*relax)(struct hwspinlock *lock);
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};
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/**
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* struct hwspinlock - this struct represents a single hwspinlock instance
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* @bank: the hwspinlock_device structure which owns this lock
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* @lock: initialized and used by hwspinlock core
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* @priv: private data, owned by the underlying platform-specific hwspinlock drv
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*/
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struct hwspinlock {
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struct hwspinlock_device *bank;
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spinlock_t lock;
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void *priv;
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};
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/**
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* struct hwspinlock_device - a device which usually spans numerous hwspinlocks
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* @dev: underlying device, will be used to invoke runtime PM api
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* @ops: platform-specific hwspinlock handlers
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* @base_id: id index of the first lock in this device
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* @num_locks: number of locks in this device
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* @lock: dynamically allocated array of 'struct hwspinlock'
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*/
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struct hwspinlock_device {
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struct device *dev;
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const struct hwspinlock_ops *ops;
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int base_id;
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int num_locks;
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struct hwspinlock lock[];
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};
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static inline int hwlock_to_id(struct hwspinlock *hwlock)
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{
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int local_id = hwlock - &hwlock->bank->lock[0];
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return hwlock->bank->base_id + local_id;
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}
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#endif /* __HWSPINLOCK_HWSPINLOCK_H */
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