From 96928d9032a7c34f12a88df879665562bcebf59a Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Sat, 15 Apr 2023 19:01:10 +0900 Subject: seq_buf: Add seq_buf_do_printk() helper Sometimes we use seq_buf to format a string buffer, which we then pass to printk(). However, in certain situations the seq_buf string buffer can get too big, exceeding the PRINTKRB_RECORD_MAX bytes limit, and causing printk() to truncate the string. Add a new seq_buf helper. This helper prints the seq_buf string buffer line by line, using \n as a delimiter, rather than passing the whole string buffer to printk() at once. Link: https://lkml.kernel.org/r/20230415100110.1419872-1-senozhatsky@chromium.org Cc: Andrew Morton Signed-off-by: Sergey Senozhatsky Reviewed-by: Petr Mladek Tested-by: Yosry Ahmed Signed-off-by: Steven Rostedt (Google) --- lib/seq_buf.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'lib/seq_buf.c') diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 0a68f7aa85d6..45c450f423fa 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -93,6 +93,38 @@ int seq_buf_printf(struct seq_buf *s, const char *fmt, ...) } EXPORT_SYMBOL_GPL(seq_buf_printf); +/** + * seq_buf_do_printk - printk seq_buf line by line + * @s: seq_buf descriptor + * @lvl: printk level + * + * printk()-s a multi-line sequential buffer line by line. The function + * makes sure that the buffer in @s is nul terminated and safe to read + * as a string. + */ +void seq_buf_do_printk(struct seq_buf *s, const char *lvl) +{ + const char *start, *lf; + + if (s->size == 0 || s->len == 0) + return; + + seq_buf_terminate(s); + + start = s->buffer; + while ((lf = strchr(start, '\n'))) { + int len = lf - start + 1; + + printk("%s%.*s", lvl, len, start); + start = ++lf; + } + + /* No trailing LF */ + if (start < s->buffer + s->len) + printk("%s%s\n", lvl, start); +} +EXPORT_SYMBOL_GPL(seq_buf_do_printk); + #ifdef CONFIG_BINARY_PRINTF /** * seq_buf_bprintf - Write the printf string from binary arguments -- cgit