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Date: Sat, 24 Sep 2022 02:10:52 +0206
From: John Ogness <john.ogness@...utronix.de>
To: Petr Mladek <pmladek@...e.com>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: [PATCH printk 16/18] printk: Use struct cons_text_buf
From: Thomas Gleixner <tglx@...utronix.de>
Replace the separately allocated output buffers with a single instance of
struct cons_text_buf.
Note that the buffer size of devkmsg_user.text_buf, when replaced with
cons_text_buf.text, reduces from CONSOLE_EXT_LOG_MAX to CONSOLE_LOG_MAX.
However, the buffer is only used to read ringbuffer records, which have
a maximum size of LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX).
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
kernel/printk/printk.c | 50 ++++++++++++++++++------------------------
1 file changed, 21 insertions(+), 29 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 65e9903d066f..9cbd44e9fc45 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -671,11 +671,9 @@ struct devkmsg_user {
atomic64_t seq;
struct ratelimit_state rs;
struct mutex lock;
- char buf[CONSOLE_EXT_LOG_MAX];
-
struct printk_info info;
- char text_buf[CONSOLE_EXT_LOG_MAX];
struct printk_record record;
+ struct cons_text_buf txtbuf;
};
static __printf(3, 4) __cold
@@ -758,6 +756,8 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
{
struct devkmsg_user *user = file->private_data;
struct printk_record *r = &user->record;
+ char *outbuf = user->txtbuf.ext_text;
+ const int maxlen = sizeof(user->txtbuf.ext_text);
size_t len;
ssize_t ret;
@@ -798,8 +798,8 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
goto out;
}
- len = info_print_ext_header(user->buf, sizeof(user->buf), r->info);
- len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
+ len = info_print_ext_header(outbuf, maxlen, r->info);
+ len += msg_print_ext_body(outbuf + len, maxlen - len,
&r->text_buf[0], r->info->text_len,
&r->info->dev_info);
@@ -810,7 +810,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
goto out;
}
- if (copy_to_user(buf, user->buf, len)) {
+ if (copy_to_user(buf, outbuf, len)) {
ret = -EFAULT;
goto out;
}
@@ -909,7 +909,8 @@ static int devkmsg_open(struct inode *inode, struct file *file)
mutex_init(&user->lock);
prb_rec_init_rd(&user->record, &user->info,
- &user->text_buf[0], sizeof(user->text_buf));
+ user->txtbuf.text,
+ sizeof(user->txtbuf.text));
atomic64_set(&user->seq, prb_first_valid_seq(prb));
@@ -2709,8 +2710,8 @@ static void __console_unlock(void)
*
* Requires the console_lock.
*/
-static bool console_emit_next_record(struct console *con, char *text, char *ext_text,
- char *dropped_text, bool *handover)
+static bool console_emit_next_record(struct console *con, struct cons_text_buf *txtbuf,
+ bool *handover, bool extmsg)
{
static int panic_console_dropped;
struct printk_info info;
@@ -2719,7 +2720,7 @@ static bool console_emit_next_record(struct console *con, char *text, char *ext_
char *write_text;
size_t len;
- prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
+ prb_rec_init_rd(&r, &info, txtbuf->text, CONSOLE_LOG_MAX);
*handover = false;
@@ -2741,13 +2742,13 @@ static bool console_emit_next_record(struct console *con, char *text, char *ext_
goto skip;
}
- if (ext_text) {
- write_text = ext_text;
- len = info_print_ext_header(ext_text, CONSOLE_EXT_LOG_MAX, r.info);
- len += msg_print_ext_body(ext_text + len, CONSOLE_EXT_LOG_MAX - len,
+ if (extmsg) {
+ write_text = txtbuf->ext_text;
+ len = info_print_ext_header(write_text, CONSOLE_EXT_LOG_MAX, r.info);
+ len += msg_print_ext_body(write_text + len, CONSOLE_EXT_LOG_MAX - len,
&r.text_buf[0], r.info->text_len, &r.info->dev_info);
} else {
- write_text = text;
+ write_text = txtbuf->text;
len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time);
}
@@ -2765,7 +2766,7 @@ static bool console_emit_next_record(struct console *con, char *text, char *ext_
console_lock_spinning_enable();
stop_critical_timings(); /* don't trace print latency */
- call_console_driver(con, write_text, len, dropped_text);
+ call_console_driver(con, write_text, len, extmsg ? NULL : txtbuf->dropped_text);
start_critical_timings();
con->seq++;
@@ -2801,9 +2802,7 @@ static bool console_emit_next_record(struct console *con, char *text, char *ext_
*/
static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handover)
{
- static char dropped_text[DROPPED_TEXT_MAX];
- static char ext_text[CONSOLE_EXT_LOG_MAX];
- static char text[CONSOLE_LOG_MAX];
+ static struct cons_text_buf txtbuf;
bool any_usable = false;
struct console *con;
bool any_progress;
@@ -2821,16 +2820,9 @@ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handove
continue;
any_usable = true;
- if (con->flags & CON_EXTENDED) {
- /* Extended consoles do not print "dropped messages". */
- progress = console_emit_next_record(con, &text[0],
- &ext_text[0], NULL,
- handover);
- } else {
- progress = console_emit_next_record(con, &text[0],
- NULL, &dropped_text[0],
- handover);
- }
+ progress = console_emit_next_record(con, &txtbuf, handover,
+ con->flags & CON_EXTENDED);
+
if (*handover)
return false;
--
2.30.2
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