From: John Ogness <john.ogness@linutronix.de>
To: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: [PATCH printk-rework 05/14] printk: introduce CONSOLE_LOG_MAX for improved multi-line support
Date: Thu, 18 Feb 2021 09:18:08 +0100 [thread overview]
Message-ID: <20210218081817.28849-6-john.ogness@linutronix.de> (raw)
In-Reply-To: <20210218081817.28849-1-john.ogness@linutronix.de>
Instead of using "LOG_LINE_MAX + PREFIX_MAX" for temporary buffer
sizes, introduce CONSOLE_LOG_MAX. This represents the maximum size
that is allowed to be printed to the console for a single record.
Rather than setting CONSOLE_LOG_MAX to "LOG_LINE_MAX + PREFIX_MAX"
(1024), increase it to 4096. With a larger buffer size, multi-line
records that are nearly LOG_LINE_MAX in length will have a better
chance of being fully printed. (When formatting a record for the
console, each line of a multi-line record is prepended with a copy
of the prefix.)
Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
kernel/printk/printk.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index d6f93ebd7bd0..f79e7515b5f1 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -410,8 +410,13 @@ static u64 clear_seq;
#else
#define PREFIX_MAX 32
#endif
+
+/* the maximum size allowed to be reserved for a record */
#define LOG_LINE_MAX (1024 - PREFIX_MAX)
+/* the maximum size of a formatted record (i.e. with prefix added per line) */
+#define CONSOLE_LOG_MAX 4096
+
#define LOG_LEVEL(v) ((v) & 0x07)
#define LOG_FACILITY(v) ((v) >> 3 & 0xff)
@@ -1473,11 +1478,11 @@ static int syslog_print(char __user *buf, int size)
char *text;
int len = 0;
- text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+ text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
- prb_rec_init_rd(&r, &info, text, LOG_LINE_MAX + PREFIX_MAX);
+ prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
while (size > 0) {
size_t n;
@@ -1543,7 +1548,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
u64 seq;
bool time;
- text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+ text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
@@ -1555,7 +1560,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
*/
seq = find_first_fitting_seq(clear_seq, -1, size, true, time);
- prb_rec_init_rd(&r, &info, text, LOG_LINE_MAX + PREFIX_MAX);
+ prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
len = 0;
prb_for_each_record(seq, prb, seq, &r) {
@@ -2188,8 +2193,7 @@ EXPORT_SYMBOL(printk);
#else /* CONFIG_PRINTK */
-#define LOG_LINE_MAX 0
-#define PREFIX_MAX 0
+#define CONSOLE_LOG_MAX 0
#define printk_time false
#define prb_read_valid(rb, seq, r) false
@@ -2500,7 +2504,7 @@ static inline int can_use_console(void)
void console_unlock(void)
{
static char ext_text[CONSOLE_EXT_LOG_MAX];
- static char text[LOG_LINE_MAX + PREFIX_MAX];
+ static char text[CONSOLE_LOG_MAX];
unsigned long flags;
bool do_cond_resched, retry;
struct printk_info info;
--
2.20.1
next prev parent reply other threads:[~2021-02-18 9:40 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-18 8:18 [PATCH printk-rework 00/14] printk: remove logbuf_lock John Ogness
2021-02-18 8:18 ` [PATCH printk-rework 01/14] printk: limit second loop of syslog_print_all John Ogness
2021-02-18 16:15 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 02/14] printk: kmsg_dump: remove unused fields John Ogness
2021-02-18 16:18 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 03/14] printk: refactor kmsg_dump_get_buffer() John Ogness
2021-02-18 8:18 ` [PATCH printk-rework 04/14] printk: consolidate kmsg_dump_get_buffer/syslog_print_all code John Ogness
2021-02-19 12:28 ` Petr Mladek
2021-02-18 8:18 ` John Ogness [this message]
2021-02-19 12:44 ` [PATCH printk-rework 05/14] printk: introduce CONSOLE_LOG_MAX for improved multi-line support Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 06/14] printk: use seqcount_latch for clear_seq John Ogness
2021-02-18 8:18 ` [PATCH printk-rework 07/14] printk: use atomic64_t for devkmsg_user.seq John Ogness
2021-02-19 12:59 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 08/14] printk: add syslog_lock John Ogness
2021-02-19 13:30 ` Petr Mladek
2021-02-19 14:45 ` John Ogness
2021-02-19 16:33 ` John Ogness
2021-02-21 21:39 ` Helge Deller
2021-02-22 16:28 ` Petr Mladek
2021-02-23 12:22 ` Helge Deller
2021-02-23 14:23 ` Petr Mladek
2021-02-23 14:45 ` Helge Deller
2021-02-22 16:05 ` Petr Mladek
2021-02-22 16:43 ` John Ogness
2021-02-23 14:38 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 09/14] printk: introduce a kmsg_dump iterator John Ogness
2021-02-19 15:56 ` Petr Mladek
2021-02-19 16:50 ` Michael Kelley
2021-02-19 17:57 ` synchronization model: was: " Petr Mladek
2021-02-24 12:27 ` John Ogness
2021-02-24 15:40 ` John Ogness
2021-02-25 12:33 ` Petr Mladek
2021-02-26 8:36 ` John Ogness
2021-02-26 9:48 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 10/14] um: synchronize kmsg_dumper John Ogness
2021-02-18 8:18 ` [PATCH printk-rework 11/14] printk: remove logbuf_lock John Ogness
2021-02-23 11:44 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 12/14] printk: kmsg_dump: remove _nolock() variants John Ogness
2021-02-23 11:51 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 13/14] printk: kmsg_dump: use kmsg_dump_rewind John Ogness
2021-02-23 11:53 ` Petr Mladek
2021-02-18 8:18 ` [PATCH printk-rework 14/14] printk: console: remove unnecessary safe buffer usage John Ogness
2021-02-23 12:55 ` Petr Mladek
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