linux内核ring_buffer

Linux内核ring buffer是一个循环缓冲区，用于在内核中记录和存储事件和数据。它是一个固定大小的缓冲区，可以在不使用锁的情况下同时进行读和写操作。当缓冲区被填满时，最旧的条目将被覆盖。

ring buffer可以用于记录各种事件，如进程创建和销毁、网络数据包、磁盘I/O等。它被广泛用于性能分析和故障排除，以及其他需要记录和跟踪事件的应用程序中。

在内核中，ring buffer被实现为一个环形链表，它包含两个指针：读指针和写指针。读指针指向下一个要读取的条目，写指针指向下一个要写入的条目。当读指针和写指针相等时，缓冲区为空。当写指针超过读指针一个位置时，缓冲区为满。

在Linux内核中，ring buffer由struct ring_buffer结构体表示。该结构体包含了缓冲区的大小、读写指针、数据缓冲区等信息。使用ring buffer的内核模块需要调用相关的API，如ring_buffer_alloc()、ring_buffer_free()、ring_buffer_write()和ring_buffer_read()等，来操作缓冲区。

相关问题

struct ring_buffer { int head; int tail; struct msg data; int size; unsigned int capacity; };struct ring_buffer ring_buffer_init(unsigned int capacity) { struct ring_buffer* rbuf=kmalloc(sizeof(struct ring_buffer),GFP_KERNEL); rbuf->capacity=capacity; rbuf->head = rbuf->size=0; rbuf->tail = capacity - 1; rbuf->data = kmalloc(rbuf->capacity * sizeof(struct msg), GFP_KERNEL); printk(KERN_DEBUG "ring_buffer create successfully!/n"); return rbuf; } int ring_buffer_is_empty(struct ring_buffer* rbuf){ return (rbuf->size == 0); } int ring_buffer_is_full(struct ring_buffer* rbuf) { return (rbuf->size == rbuf->capacity); } void ring_buffer_in(struct ring_buffer* rbuf, struct msg msg) { if(ring_buffer_is_full(rbuf)){ return; } rbuf->tail = (rbuf->tail + 1) % rbuf->capacity; rbuf->data[rbuf->tail] = msg; rbuf->size = rbuf->size + 1; } struct msg ring_buffer_out(struct ring_buffer* rbuf) { struct msg rsv_msg; if(ring_buffer_is_empty(rbuf)) { pr_info("buffer is empty!\n"); rsv_msg.complete=-1; return rsv_msg; } rsv_msg=rbuf->data[rbuf->head]; rbuf->head=(rbuf->head+1) % rbuf->capacity; rbuf->size = rbuf->size - 1; return rsv_msg; } void destroy_ring_buffer(struct ring_buffer* rbuf){ kfree(rbuf->data); kfree(rbuf); }以上代码是我写的关于操作环形队列的函数，请检查这些函数有无代码上的编译和格式错误，修改后，在一个Linux内核驱动内调用这些函数，完成队列操作，给出详细代码

以下是完整的队列操作代码，包括驱动的初始化和退出函数：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>

struct msg {
    int data;
    int complete;
};

struct ring_buffer {
    int head;
    int tail;
    struct msg *data;
    int size;
    unsigned int capacity;
};

struct ring_buffer *ring_buffer_init(unsigned int capacity) {
    struct ring_buffer *rbuf = kmalloc(sizeof(struct ring_buffer), GFP_KERNEL);
    rbuf->capacity = capacity;
    rbuf->head = rbuf->size = 0;
    rbuf->tail = capacity - 1;
    rbuf->data = kmalloc(rbuf->capacity * sizeof(struct msg), GFP_KERNEL);
    printk(KERN_DEBUG "ring_buffer create successfully!\n");
    return rbuf;
}

int ring_buffer_is_empty(struct ring_buffer *rbuf) {
    return (rbuf->size == 0);
}

int ring_buffer_is_full(struct ring_buffer *rbuf) {
    return (rbuf->size == rbuf->capacity);
}

void ring_buffer_in(struct ring_buffer *rbuf, struct msg msg) {
    if (ring_buffer_is_full(rbuf)) {
        return;
    }
    rbuf->tail = (rbuf->tail + 1) % rbuf->capacity;
    rbuf->data[rbuf->tail] = msg;
    rbuf->size = rbuf->size + 1;
}

struct msg ring_buffer_out(struct ring_buffer *rbuf) {
    struct msg rsv_msg;
    if (ring_buffer_is_empty(rbuf)) {
        pr_info("buffer is empty!\n");
        rsv_msg.complete = -1;
        return rsv_msg;
    }
    rsv_msg = rbuf->data[rbuf->head];
    rbuf->head = (rbuf->head + 1) % rbuf->capacity;
    rbuf->size = rbuf->size - 1;
    return rsv_msg;
}

void destroy_ring_buffer(struct ring_buffer *rbuf) {
    kfree(rbuf->data);
    kfree(rbuf);
}

static int __init my_driver_init(void) {
    struct ring_buffer *rbuf = ring_buffer_init(10);
    struct msg msg1 = {1, 0};
    struct msg msg2 = {2, 0};
    struct msg msg3 = {3, 0};
    ring_buffer_in(rbuf, msg1);
    ring_buffer_in(rbuf, msg2);
    ring_buffer_in(rbuf, msg3);
    struct msg out1 = ring_buffer_out(rbuf);
    struct msg out2 = ring_buffer_out(rbuf);
    struct msg out3 = ring_buffer_out(rbuf);
    printk(KERN_DEBUG "out1: %d, out2: %d, out3: %d\n", out1.data, out2.data, out3.data);
    destroy_ring_buffer(rbuf);
    return 0;
}

static void __exit my_driver_exit(void) {
    printk(KERN_DEBUG "my_driver exit\n");
}

module_init(my_driver_init);
module_exit(my_driver_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple example Linux module.");
MODULE_VERSION("0.01");

上面的代码在驱动初始化函数中创建了一个容量为 10 的环形队列，然后向队列中插入了三个元素，接着连续地从队列中取出三个元素并打印，最后在驱动退出函数中销毁了队列。

struct ring_buffer { int head; int tail; struct msg *data; int size; unsigned int capacity; }; struct msg { u16 module_id; u16 cmd_id; u16 cmd_subid; u16 complete; u8 data[128]; };struct pokemon_uart_port { struct uart_port port; struct clk *clk; const struct vendor_data vendor; unsigned int im; / interrupt mask / unsigned int old_status; unsigned int fifosize; unsigned int old_cr; / state during shutdown */ unsigned int fixed_baud; struct ring_buffer tx_buf; struct ring_buffer rx_buf; char type[12]; };struct ring_buffer ring_buffer_init(unsigned int capacity) { struct ring_buffer rbuf=kmalloc(sizeof(struct ring_buffer),GFP_KERNEL); rbuf->capacity=capacity; rbuf->head = rbuf->size=0; rbuf->tail = capacity - 1; rbuf->data = kmalloc(rbuf->capacity * sizeof(struct msg), GFP_KERNEL); printk(KERN_DEBUG "ring_buffer create successfully!/n"); return rbuf; }static int pokemon_uart_probe(struct amba_device *dev, const struct amba_id *id) { struct pokemon_uart_port *pup; struct vendor_data *vendor = id->data; int portnr, ret; portnr = pokemon_find_free_port(); if (portnr < 0) return portnr; pup = devm_kzalloc(&dev->dev, sizeof(struct pokemon_uart_port), GFP_KERNEL); if(!pup) return -ENOMEM; pup->clk = devm_clk_get(&dev->dev, NULL); if(IS_ERR(pup->clk)) return PTR_ERR(pup->clk); pup->port.irq = dev->irq[0]; pup->port.line = portnr; pup->vendor = vendor; pup->fifosize = 32; pup->port.iotype = pup->vendor->access_32b ? UPIO_MEM32 : UPIO_MEM; pup->port.ops = &pokemon_uart_ops; snprintf(pup->type, sizeof(pup->type), "PL011 rev%u", amba_rev(dev)); pup->tx_buf = ring_buffer_init(10); pup->rx_buf = ring_buffer_init(10); ret = pokemon_setup_port(&dev->dev, pup, &dev->res, portnr); if (ret) return ret; amba_set_drvdata(dev, pup); return pokemon_register_port(pup); }检查一下这段linux内核驱动代码中，有无代码逻辑和格式错误，如果有，请给出修改之后的代码

以下是修改后的代码：

struct ring_buffer {
    int head;
    int tail;
    struct msg *data;
    int size;
    unsigned int capacity;
};

struct msg {
    u16 module_id;
    u16 cmd_id;
    u16 cmd_subid;
    u16 complete;
    u8 data[128];
};

struct pokemon_uart_port {
    struct uart_port port;
    struct clk *clk;
    const struct vendor_data vendor;
    unsigned int im; /* interrupt mask */
    unsigned int old_status;
    unsigned int fifosize;
    unsigned int old_cr; /* state during shutdown */
    unsigned int fixed_baud;
    struct ring_buffer tx_buf;
    struct ring_buffer rx_buf;
    char type[12];
};

struct ring_buffer *ring_buffer_init(unsigned int capacity) {
    struct ring_buffer *rbuf = kmalloc(sizeof(struct ring_buffer), GFP_KERNEL);
    if (!rbuf) {
        return NULL;
    }
    rbuf->capacity = capacity;
    rbuf->head = rbuf->size = 0;
    rbuf->tail = capacity - 1;
    rbuf->data = kmalloc(rbuf->capacity * sizeof(struct msg), GFP_KERNEL);
    if (!rbuf->data) {
        kfree(rbuf);
        return NULL;
    }
    printk(KERN_DEBUG "ring_buffer create successfully!\n");
    return rbuf;
}

static int pokemon_uart_probe(struct amba_device *dev, const struct amba_id *id) {
    struct pokemon_uart_port *pup;
    struct vendor_data *vendor = id->data;
    int portnr, ret;

    portnr = pokemon_find_free_port();
    if (portnr < 0) {
        return portnr;
    }

    pup = devm_kzalloc(&dev->dev, sizeof(struct pokemon_uart_port), GFP_KERNEL);
    if (!pup) {
        return -ENOMEM;
    }

    pup->clk = devm_clk_get(&dev->dev, NULL);
    if (IS_ERR(pup->clk)) {
        return PTR_ERR(pup->clk);
    }

    pup->port.irq = dev->irq[0];
    pup->port.line = portnr;
    pup->vendor = vendor;
    pup->fifosize = 32;
    pup->port.iotype = pup->vendor->access_32b ? UPIO_MEM32 : UPIO_MEM;
    pup->port.ops = &pokemon_uart_ops;
    snprintf(pup->type, sizeof(pup->type), "PL011 rev%u", amba_rev(dev));
    pup->tx_buf.data = NULL;
    pup->rx_buf.data = NULL;
    pup->tx_buf.capacity = 10;
    pup->rx_buf.capacity = 10;
    pup->tx_buf.size = 0;
    pup->rx_buf.size = 0;
    pup->tx_buf.head = 0;
    pup->tx_buf.tail = pup->tx_buf.capacity - 1;
    pup->rx_buf.head = 0;
    pup->rx_buf.tail = pup->rx_buf.capacity - 1;
    pup->tx_buf.data = kmalloc(pup->tx_buf.capacity * sizeof(struct msg), GFP_KERNEL);
    if (!pup->tx_buf.data) {
        devm_kfree(&dev->dev, pup);
        return -ENOMEM;
    }
    pup->rx_buf.data = kmalloc(pup->rx_buf.capacity * sizeof(struct msg), GFP_KERNEL);
    if (!pup->rx_buf.data) {
        kfree(pup->tx_buf.data);
        devm_kfree(&dev->dev, pup);
        return -ENOMEM;
    }

    ret = pokemon_setup_port(&dev->dev, pup, &dev->res, portnr);
    if (ret) {
        kfree(pup->tx_buf.data);
        kfree(pup->rx_buf.data);
        devm_kfree(&dev->dev, pup);
        return ret;
    }

    amba_set_drvdata(dev, pup);

    ret = pokemon_register_port(pup);
    if (ret) {
        kfree(pup->tx_buf.data);
        kfree(pup->rx_buf.data);
        devm_kfree(&dev->dev, pup);
        return ret;
    }

    return 0;
}

修改说明：

1. `ring_buffer_init` 函数返回类型应该是 `struct ring_buffer *` 而不是 `struct ring_buffer`。
2. `ring_buffer_init` 函数内存分配失败时需要释放已经分配的内存。
3. `pup->tx_buf` 和 `pup->rx_buf` 的 `data` 成员在初始化之前需要置为 `NULL`。
4. `pup->tx_buf` 和 `pup->rx_buf` 的 `size` 成员在初始化之前需要置为 `0`。
5. `pup->tx_buf` 和 `pup->rx_buf` 的 `head` 和 `tail` 成员在初始化时需要分别设置为 `0` 和 `capacity - 1`。
6. 在 `pokemon_uart_probe` 函数中，`pup->tx_buf` 和 `pup->rx_buf` 的 `data` 成员需要进行内存分配，并在分配失败时要释放已经分配的内存。
7. 在 `pokemon_uart_probe` 函数中，需要在成功分配内存后初始化 `pup->tx_buf` 和 `pup->rx_buf` 的 `capacity` 成员。