Messages in this thread Patch in this message | | | From | Sergey Senozhatsky <> | Subject | [PATCHv2] seq_buf: add seq_buf_do_printk() helper | Date | Tue, 11 Apr 2023 23:38:52 +0900 |
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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.
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> --- include/linux/seq_buf.h | 2 ++ lib/seq_buf.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h index 5b31c5147969..515d7fcb9634 100644 --- a/include/linux/seq_buf.h +++ b/include/linux/seq_buf.h @@ -159,4 +159,6 @@ extern int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary); #endif +void seq_buf_do_printk(struct seq_buf *s, const char *lvl); + #endif /* _LINUX_SEQ_BUF_H */ diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 0a68f7aa85d6..be7227d42b20 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -93,6 +93,40 @@ 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; + int len; + + if (s->size == 0 || s->len == 0) + return; + + seq_buf_terminate(s); + + start = s->buffer; + while ((lf = strchr(start, '\n'))) { + len = lf - start + 1; + printk("%s%.*s", lvl, len, start); + start = ++lf; + } + + /* No trailing LF */ + if (start < s->buffer + s->len) { + len = s->buffer + s->len - start; + printk("%s%.*s\n", lvl, len, start); + } +} +EXPORT_SYMBOL_GPL(seq_buf_do_printk); + #ifdef CONFIG_BINARY_PRINTF /** * seq_buf_bprintf - Write the printf string from binary arguments -- 2.40.0.577.gac1e443424-goog
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