The patch titled
Subject: seq_buf: add seq_buf_do_printk() helper
has been added to the -mm mm-unstable branch. Its filename is
seq_buf-add-seq_buf_do_printk-helper.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/seq_buf-add-seq_buf_do_printk-helper.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: seq_buf: add seq_buf_do_printk() helper
Date: Sat, 15 Apr 2023 19:01:10 +0900
(akpm: temporary addition for
memcg-use-seq_buf_do_printk-with-mem_cgroup_print_oom_meminfo.patch)
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 as a delimiter, rather than passing the whole string
buffer to printk() at once.
Link: https://lkml.kernel.org/r/20230415100110.1419872-1-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/seq_buf.h | 2 ++
lib/seq_buf.c | 32 ++++++++++++++++++++++++++++++++
2 files changed, 34 insertions(+)
--- a/include/linux/seq_buf.h~seq_buf-add-seq_buf_do_printk-helper
+++ a/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 */
--- a/lib/seq_buf.c~seq_buf-add-seq_buf_do_printk-helper
+++ a/lib/seq_buf.c
@@ -93,6 +93,38 @@ int seq_buf_printf(struct seq_buf *s, co
}
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
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
seq_buf-add-seq_buf_do_printk-helper.patch
