linux-kernel - Re: [PATCH v7 2/4] Bluetooth: Add vhci devcoredump support

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Date:   Thu, 2 Mar 2023 16:32:06 -0800
From:   Luiz Augusto von Dentz <luiz.dentz@...il.com>
To:     Manish Mandlik <mmandlik@...gle.com>
Cc:     marcel@...tmann.org, chromeos-bluetooth-upstreaming@...omium.org,
        linux-bluetooth@...r.kernel.org,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/4] Bluetooth: Add vhci devcoredump support

Hi Manish,

On Thu, Mar 2, 2023 at 3:15 PM Manish Mandlik <mmandlik@...gle.com> wrote:
>
> Add devcoredump support for vhci that creates forcce_devcoredump debugfs
> entry. This is used for mgmt-tester tests.
>
> Signed-off-by: Manish Mandlik <mmandlik@...gle.com>
> ---
>
> Changes in v7:
> - New patch in the series
>
>  drivers/bluetooth/Kconfig    |  1 +
>  drivers/bluetooth/hci_vhci.c | 72 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 73 insertions(+)
>
> diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
> index 5a1a7bec3c42..7bc7a765ad69 100644
> --- a/drivers/bluetooth/Kconfig
> +++ b/drivers/bluetooth/Kconfig
> @@ -363,6 +363,7 @@ config BT_HCIBLUECARD
>
>  config BT_HCIVHCI
>         tristate "HCI VHCI (Virtual HCI device) driver"
> +       select WANT_DEV_COREDUMP
>         help
>           Bluetooth Virtual HCI device driver.
>           This driver is required if you want to use HCI Emulation software.
> diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
> index c443c3b0a4da..8a74e66f8b8e 100644
> --- a/drivers/bluetooth/hci_vhci.c
> +++ b/drivers/bluetooth/hci_vhci.c
> @@ -278,6 +278,75 @@ static int vhci_setup(struct hci_dev *hdev)
>         return 0;
>  }
>
> +static void vhci_coredump(struct hci_dev *hdev)
> +{
> +       /* No need to do anything */
> +}
> +
> +static int vhci_coredump_hdr(struct hci_dev *hdev, char *buf, size_t size)
> +{
> +       char *ptr = buf;
> +       size_t rem = size;
> +       size_t read = 0;
> +
> +       read = snprintf(ptr, rem, "Controller Name: vhci_ctrl\n");
> +       rem -= read;
> +       ptr += read;

Don't really like these pointer operations, can't we pass the skb here
and then use the likes of skb_push?

> +       read = snprintf(ptr, rem, "Firmware Version: vhci_fw\n");
> +       rem -= read;
> +       ptr += read;
> +
> +       read = snprintf(ptr, rem, "Driver: vhci_drv\n");
> +       rem -= read;
> +       ptr += read;
> +
> +       read = snprintf(ptr, rem, "Vendor: vhci\n");
> +       rem -= read;
> +       ptr += read;
> +
> +       return size - rem;
> +}
> +
> +static ssize_t force_devcoredump_write(struct file *file,
> +                                      const char __user *user_buf,
> +                                      size_t count, loff_t *ppos)
> +{
> +       struct vhci_data *data = file->private_data;
> +       struct hci_dev *hdev = data->hdev;
> +       struct sk_buff *skb = NULL;
> +       char buf[512];
> +       int ret;
> +
> +       ret = simple_write_to_buffer(&buf, sizeof(buf), ppos, user_buf, count);
> +       if (ret < count)
> +               return ret;
> +
> +       skb = alloc_skb(count, GFP_ATOMIC);
> +       if (!skb)
> +               return -ENOMEM;
> +       skb_put_data(skb, &buf, count);
> +
> +       hci_devcoredump_register(hdev, vhci_coredump, vhci_coredump_hdr, NULL);
> +
> +       ret = hci_devcoredump_init(hdev, skb->len);
> +       if (ret) {
> +               BT_ERR("Failed to generate devcoredump");
> +               kfree_skb(skb);
> +               return ret;
> +       }
> +
> +       hci_devcoredump_append(hdev, skb);
> +       hci_devcoredump_complete(hdev);
> +
> +       return count;
> +}
> +
> +static const struct file_operations force_devcoredump_fops = {
> +       .open           = simple_open,
> +       .write          = force_devcoredump_write,
> +};
> +
>  static int __vhci_create_device(struct vhci_data *data, __u8 opcode)
>  {
>         struct hci_dev *hdev;
> @@ -355,6 +424,9 @@ static int __vhci_create_device(struct vhci_data *data, __u8 opcode)
>                 debugfs_create_file("aosp_capable", 0644, hdev->debugfs, data,
>                                     &aosp_capable_fops);
>
> +       debugfs_create_file("force_devcoredump", 0644, hdev->debugfs, data,
> +                           &force_devcoredump_fops);
> +
>         hci_skb_pkt_type(skb) = HCI_VENDOR_PKT;
>
>         skb_put_u8(skb, 0xff);
> --
> 2.40.0.rc0.216.gc4246ad0f0-goog
>


-- 
Luiz Augusto von Dentz