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References: <20200127164943.220776-1-marcel@holtmann.org>
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From:   Alain Michaud <alainmichaud@google.com>
Date:   Thu, 30 Jan 2020 09:19:03 -0500
Message-ID: <CALWDO_ViEZsqAw-TA5rJ=NfrGpgQJsM2TCoZfoXPOghGi=9Vmg@mail.gmail.com>
Subject: Re: [RFC] Bluetooth: Add debugfs option to enable runtime debug statements
To:     Marcel Holtmann <marcel@holtmann.org>,
        Archie Pusaka <apusaka@google.com>
Cc:     BlueZ <linux-bluetooth@vger.kernel.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Adding +Archie Pusaka for comments.

Thanks,
Alain


On Mon, Jan 27, 2020 at 11:49 AM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
> ---
>  include/net/bluetooth/bluetooth.h | 10 ++++-
>  net/bluetooth/Kconfig             |  4 ++
>  net/bluetooth/af_bluetooth.c      |  2 +
>  net/bluetooth/lib.c               | 69 +++++++++++++++++++++++++++++++
>  4 files changed, 84 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
> index e42bb8e03c09..d32d1f401efb 100644
> --- a/include/net/bluetooth/bluetooth.h
> +++ b/include/net/bluetooth/bluetooth.h
> @@ -129,6 +129,8 @@ void bt_warn(const char *fmt, ...);
>  __printf(1, 2)
>  void bt_err(const char *fmt, ...);
>  __printf(1, 2)
> +void bt_dbg(const char *fmt, ...);
> +__printf(1, 2)
>  void bt_warn_ratelimited(const char *fmt, ...);
>  __printf(1, 2)
>  void bt_err_ratelimited(const char *fmt, ...);
> @@ -136,7 +138,11 @@ void bt_err_ratelimited(const char *fmt, ...);
>  #define BT_INFO(fmt, ...)      bt_info(fmt "\n", ##__VA_ARGS__)
>  #define BT_WARN(fmt, ...)      bt_warn(fmt "\n", ##__VA_ARGS__)
>  #define BT_ERR(fmt, ...)       bt_err(fmt "\n", ##__VA_ARGS__)
> -#define BT_DBG(fmt, ...)       pr_debug(fmt "\n", ##__VA_ARGS__)
> +#if IS_ENABLED(CONFIG_BT_DEBUGFS_OPTION)
> +#define BT_DBG(fmt, ...)       bt_dbg(fmt "\n", ##__VA_ARGS__)
> +#else
> +#define BT_DBG(fmt, ...)       pr_debug(mt "\n", ##__VA_ARGS__)
> +#endif
>
>  #define bt_dev_info(hdev, fmt, ...)                            \
>         BT_INFO("%s: " fmt, (hdev)->name, ##__VA_ARGS__)
> @@ -393,6 +399,8 @@ void bt_procfs_cleanup(struct net *net, const char *name);
>
>  extern struct dentry *bt_debugfs;
>
> +void bt_lib_debugfs_init(void);
> +
>  int l2cap_init(void);
>  void l2cap_exit(void);
>
> diff --git a/net/bluetooth/Kconfig b/net/bluetooth/Kconfig
> index 165148c7c4ce..64833640bf3d 100644
> --- a/net/bluetooth/Kconfig
> +++ b/net/bluetooth/Kconfig
> @@ -128,4 +128,8 @@ config BT_DEBUGFS
>           Provide extensive information about internal Bluetooth states
>           in debugfs.
>
> +config BT_DEBUGFS_OPTION
> +       bool
> +       default y if BT_DEBUGFS && !DYNAMIC_DEBUG
> +
>  source "drivers/bluetooth/Kconfig"
> diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
> index 3fd124927d4d..fa0cd665f32a 100644
> --- a/net/bluetooth/af_bluetooth.c
> +++ b/net/bluetooth/af_bluetooth.c
> @@ -731,6 +731,8 @@ static int __init bt_init(void)
>
>         bt_debugfs = debugfs_create_dir("bluetooth", NULL);
>
> +       bt_lib_debugfs_init();
> +
>         bt_leds_init();
>
>         err = bt_sysfs_init();
> diff --git a/net/bluetooth/lib.c b/net/bluetooth/lib.c
> index c09e0a3a0ed9..28cfc3fd8fbe 100644
> --- a/net/bluetooth/lib.c
> +++ b/net/bluetooth/lib.c
> @@ -27,6 +27,7 @@
>  #define pr_fmt(fmt) "Bluetooth: " fmt
>
>  #include <linux/export.h>
> +#include <linux/debugfs.h>
>
>  #include <net/bluetooth/bluetooth.h>
>
> @@ -135,6 +136,55 @@ int bt_to_errno(__u16 code)
>  }
>  EXPORT_SYMBOL(bt_to_errno);
>
> +#ifdef CONFIG_BT_DEBUGFS_OPTION
> +static bool debug_enable;
> +
> +static ssize_t debug_enable_read(struct file *file, char __user *user_buf,
> +                                size_t count, loff_t *ppos)
> +{
> +       char buf[3];
> +
> +       buf[0] = debug_enable ? 'Y': 'N';
> +       buf[1] = '\n';
> +       buf[2] = '\0';
> +       return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
> +}
> +
> +static ssize_t debug_enable_write(struct file *file,
> +                                 const char __user *user_buf,
> +                                 size_t count, loff_t *ppos)
> +{
> +       bool enable;
> +       int err;
> +
> +       err = kstrtobool_from_user(user_buf, count, &enable);
> +       if (err)
> +               return err;
> +
> +       if (enable == debug_enable)
> +               return -EALREADY;
> +
> +       debug_enable = enable;
> +
> +       return count;
> +}
> +
> +static const struct file_operations debug_enable_fops = {
> +       .open           = simple_open,
> +       .read           = debug_enable_read,
> +       .write          = debug_enable_write,
> +       .llseek         = default_llseek,
> +};
> +
> +void bt_lib_debugfs_init(void)
> +{
> +       debugfs_create_file("debug_enable", 0644, bt_debugfs, NULL,
> +                           &debug_enable_fops);
> +}
> +#else
> +void bt_lib_debugfs_init(void);
> +#endif
> +
>  void bt_info(const char *format, ...)
>  {
>         struct va_format vaf;
> @@ -183,6 +233,25 @@ void bt_err(const char *format, ...)
>  }
>  EXPORT_SYMBOL(bt_err);
>
> +void bt_dbg(const char *format, ...)
> +{
> +       struct va_format vaf;
> +       va_list args;
> +
> +       if (likely(!debug_enable))
> +               return;
> +
> +       va_start(args, format);
> +
> +       vaf.fmt = format;
> +       vaf.va = &args;
> +
> +       printk(KERN_DEBUG pr_fmt("%pV"), &vaf);
> +
> +       va_end(args);
> +}
> +EXPORT_SYMBOL(bt_dbg);
> +
>  void bt_warn_ratelimited(const char *format, ...)
>  {
>         struct va_format vaf;
> --
> 2.24.1
>