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Date: Mon, 20 Apr 2015 14:30:12 +0200
From: Petr Mladek <pmladek@...e.cz>
To: Tejun Heo <tj@...nel.org>
Cc: akpm@...ux-foundation.org, davem@...emloft.net,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
Kay Sievers <kay@...y.org>
Subject: Re: [PATCH 02/16] printk: factor out message formatting from
devkmsg_read()
On Thu 2015-04-16 19:03:39, Tejun Heo wrote:
> The extended message formatting used for /dev/kmsg will be used
> implement extended consoles. Factor out msg_print_ext_header() and
> msg_print_ext_body() from devkmsg_read().
>
> This is pure restructuring.
>
> Signed-off-by: Tejun Heo <tj@...nel.org>
Reviewed-by: Petr Mladek <pmladek@...e.cz>
I like the split of the long function.
Best Regards,
Petr
> Cc: Kay Sievers <kay@...y.org>
> Cc: Petr Mladek <pmladek@...e.cz>
> ---
> kernel/printk/printk.c | 157 ++++++++++++++++++++++++++-----------------------
> 1 file changed, 85 insertions(+), 72 deletions(-)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index b6e24af..5ea6709 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -505,6 +505,86 @@ int check_syslog_permissions(int type, bool from_file)
> return security_syslog(type);
> }
>
> +static void append_char(char **pp, char *e, char c)
> +{
> + if (*pp < e)
> + *(*pp)++ = c;
> +}
> +
> +static ssize_t msg_print_ext_header(char *buf, size_t size,
> + struct printk_log *msg, u64 seq,
> + enum log_flags prev_flags)
> +{
> + u64 ts_usec = msg->ts_nsec;
> + char cont = '-';
> +
> + do_div(ts_usec, 1000);
> +
> + /*
> + * If we couldn't merge continuation line fragments during the print,
> + * export the stored flags to allow an optional external merge of the
> + * records. Merging the records isn't always neccessarily correct, like
> + * when we hit a race during printing. In most cases though, it produces
> + * better readable output. 'c' in the record flags mark the first
> + * fragment of a line, '+' the following.
> + */
> + if (msg->flags & LOG_CONT && !(prev_flags & LOG_CONT))
> + cont = 'c';
> + else if ((msg->flags & LOG_CONT) ||
> + ((prev_flags & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
> + cont = '+';
> +
> + return scnprintf(buf, size, "%u,%llu,%llu,%c;",
> + (msg->facility << 3) | msg->level, seq, ts_usec, cont);
> +}
> +
> +static ssize_t msg_print_ext_body(char *buf, size_t size,
> + char *dict, size_t dict_len,
> + char *text, size_t text_len)
> +{
> + char *p = buf, *e = buf + size;
> + size_t i;
> +
> + /* escape non-printable characters */
> + for (i = 0; i < text_len; i++) {
> + unsigned char c = text[i];
> +
> + if (c < ' ' || c >= 127 || c == '\\')
> + p += scnprintf(p, e - p, "\\x%02x", c);
> + else
> + append_char(&p, e, c);
> + }
> + append_char(&p, e, '\n');
> +
> + if (dict_len) {
> + bool line = true;
> +
> + for (i = 0; i < dict_len; i++) {
> + unsigned char c = dict[i];
> +
> + if (line) {
> + append_char(&p, e, ' ');
> + line = false;
> + }
> +
> + if (c == '\0') {
> + append_char(&p, e, '\n');
> + line = true;
> + continue;
> + }
> +
> + if (c < ' ' || c >= 127 || c == '\\') {
> + p += scnprintf(p, e - p, "\\x%02x", c);
> + continue;
> + }
> +
> + append_char(&p, e, c);
> + }
> + append_char(&p, e, '\n');
> + }
> +
> + return p - buf;
> +}
>
> /* /dev/kmsg - userspace message inject/listen interface */
> struct devkmsg_user {
> @@ -565,30 +645,17 @@ static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
> return ret;
> }
>
> -static void append_char(char **pp, char *e, char c)
> -{
> - if (*pp < e)
> - *(*pp)++ = c;
> -}
> -
> static ssize_t devkmsg_read(struct file *file, char __user *buf,
> size_t count, loff_t *ppos)
> {
> struct devkmsg_user *user = file->private_data;
> struct printk_log *msg;
> - char *p, *e;
> - u64 ts_usec;
> - size_t i;
> - char cont = '-';
> size_t len;
> ssize_t ret;
>
> if (!user)
> return -EBADF;
>
> - p = user->buf;
> - e = user->buf + sizeof(user->buf);
> -
> ret = mutex_lock_interruptible(&user->lock);
> if (ret)
> return ret;
> @@ -618,71 +685,17 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
> }
>
> msg = log_from_idx(user->idx);
> - ts_usec = msg->ts_nsec;
> - do_div(ts_usec, 1000);
> -
> - /*
> - * If we couldn't merge continuation line fragments during the print,
> - * export the stored flags to allow an optional external merge of the
> - * records. Merging the records isn't always neccessarily correct, like
> - * when we hit a race during printing. In most cases though, it produces
> - * better readable output. 'c' in the record flags mark the first
> - * fragment of a line, '+' the following.
> - */
> - if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
> - cont = 'c';
> - else if ((msg->flags & LOG_CONT) ||
> - ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
> - cont = '+';
> + len = msg_print_ext_header(user->buf, sizeof(user->buf),
> + msg, user->seq, user->prev);
> + len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
> + log_dict(msg), msg->dict_len,
> + log_text(msg), msg->text_len);
>
> - p += scnprintf(p, e - p, "%u,%llu,%llu,%c;",
> - (msg->facility << 3) | msg->level,
> - user->seq, ts_usec, cont);
> user->prev = msg->flags;
> -
> - /* escape non-printable characters */
> - for (i = 0; i < msg->text_len; i++) {
> - unsigned char c = log_text(msg)[i];
> -
> - if (c < ' ' || c >= 127 || c == '\\')
> - p += scnprintf(p, e - p, "\\x%02x", c);
> - else
> - append_char(&p, e, c);
> - }
> - append_char(&p, e, '\n');
> -
> - if (msg->dict_len) {
> - bool line = true;
> -
> - for (i = 0; i < msg->dict_len; i++) {
> - unsigned char c = log_dict(msg)[i];
> -
> - if (line) {
> - append_char(&p, e, ' ');
> - line = false;
> - }
> -
> - if (c == '\0') {
> - append_char(&p, e, '\n');
> - line = true;
> - continue;
> - }
> -
> - if (c < ' ' || c >= 127 || c == '\\') {
> - p += scnprintf(p, e - p, "\\x%02x", c);
> - continue;
> - }
> -
> - append_char(&p, e, c);
> - }
> - append_char(&p, e, '\n');
> - }
> -
> user->idx = log_next(user->idx);
> user->seq++;
> raw_spin_unlock_irq(&logbuf_lock);
>
> - len = p - user->buf;
> if (len > count) {
> ret = -EINVAL;
> goto out;
> --
> 2.1.0
>
--
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