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gpu: nvgpu: unify NV_READ_ONCE and NV_WRITE_ONCE

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Implemented NV_READ_ONCE and NV_WRITE_ONCE in common code.

Jira GVSCI-10879

Signed-off-by: Richard Zhao <rizhao@nvidia.com>
Change-Id: I5465b4bd1cd44fc7bc1592da01d6be455b1fcdcc
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2541559
Reviewed-by: svc_kernel_abi <svc_kernel_abi@nvidia.com>
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: Aparna Das <aparnad@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
This commit is contained in:
Richard Zhao
2021-06-08 17:15:53 -07:00
committed by mobile promotions
parent 5ec1e0cc21
commit 9ac7550f35
5 changed files with 30 additions and 31 deletions
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28
drivers/gpu/nvgpu/include/nvgpu/barrier.h
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2017-2020, NVIDIA CORPORATION. All rights reserved.
* Copyright (c) 2017-2021, NVIDIA CORPORATION. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
@@ -44,8 +44,30 @@
#define nvgpu_smp_rmb() nvgpu_smp_rmb_impl()
#define nvgpu_smp_wmb() nvgpu_smp_wmb_impl()
#define NV_READ_ONCE(x) NV_READ_ONCE_IMPL((x))
#define NV_WRITE_ONCE(x, y) NV_WRITE_ONCE_IMPL((x), (y))
/**
* @brief Compilers can do optimizations assuming there is a single thread
* executing the code. For example, a variable read in a loop from one thread
* may not see the update from another thread because compiler has assumed that
* it's value cannot change from the one initialized before the loop. There are
* other possibilities like multiple references to a variable when the code
* assumes that it should see a constant value. In general, this macro should
* never be used by nvgpu driver code, and many of the current uses in driver
* are likely wrong.
* For more info see: URL = lwn.net/Articles/508991/
*
* @param x [in] variable that needs to turn into a volatile type temporarily.
*/
#define NV_READ_ONCE(x) (*((volatile typeof(x) *)&x))
/**
* @brief Ensure ordered writes.
*
* @param x Variable to be updated.
* @param y Value to be written.
*
* Prevent compiler optimizations from mangling writes.
*/
#define NV_WRITE_ONCE(x, y) (*((volatile typeof(x) *)(&(x))) = (y))
/*
* Sometimes we want to prevent speculation.

5
drivers/gpu/nvgpu/include/nvgpu/linux/barrier.h
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2017-2020, NVIDIA CORPORATION. All rights reserved.
* Copyright (c) 2017-2021, NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
@@ -27,9 +27,6 @@
#define nvgpu_smp_rmb_impl() smp_rmb()
#define nvgpu_smp_wmb_impl() smp_wmb()
#define NV_READ_ONCE_IMPL(x) READ_ONCE(x)
#define NV_WRITE_ONCE_IMPL(x, y) WRITE_ONCE(x, y)
#ifdef speculation_barrier
#define nvgpu_speculation_barrier_impl() speculation_barrier()
#else

7
drivers/gpu/nvgpu/include/nvgpu/posix/barrier.h
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2017-2020, NVIDIA CORPORATION. All rights reserved.
* Copyright (c) 2017-2021, NVIDIA CORPORATION. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
@@ -25,8 +25,6 @@
#include <nvgpu/posix/utils.h>
#define READ_ONCE(x) (*(volatile __typeof__(x) *)&x)
/*
* TODO: implement all these!
*/
@@ -38,7 +36,4 @@
#define nvgpu_smp_rmb_impl()
#define nvgpu_smp_wmb_impl()
#define NV_READ_ONCE_IMPL(x) READ_ONCE(x)
#define NV_WRITE_ONCE_IMPL(x, y) WRITE_ONCE(x, y)
#endif /* NVGPU_POSIX_BARRIER_H */

16
drivers/gpu/nvgpu/include/nvgpu/posix/utils.h
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@@ -496,22 +496,6 @@ static inline unsigned int nvgpu_posix_hweight64(uint64_t x)
/** Defined to match kernel macro names. */
#define likely(x) (x)
/*
* Prevent compiler optimizations from mangling writes. But likely most uses of
* this in nvgpu are incorrect (i.e unnecessary).
*/
/**
* @brief Ensure ordered writes.
*
* @param p Variable to be updated.
* @param v Value to be written.
*/
#define WRITE_ONCE(p, v) \
({ \
volatile typeof(p) *__p__ = &(p); \
*__p__ = (v); \
})
/**
* @brief Get the container which holds the member.
*

5
userspace/units/posix/utils/posix-utils.c
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@@ -27,6 +27,7 @@
#include <unit/unit.h>
#include <nvgpu/utils.h>
#include <nvgpu/barrier.h>
#include "posix-utils.h"
@@ -487,10 +488,10 @@ int test_write_once(struct unit_module *m,
test1 = 20;
for (i = 0 ; i < 10; i++) {
test1 += 1;
WRITE_ONCE(result, test1);
NV_WRITE_ONCE(result, test1);
if (result != test1) {
unit_return_fail(m,
"WRITE_ONCE failure %d\n", result);
"NV_WRITE_ONCE failure %d\n", result);
}
}