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Date: Sat, 24 Sep 2022 02:10:53 +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,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH printk 17/18] printk: Use an output descriptor struct for emit
From: Thomas Gleixner <tglx@...utronix.de>
To prepare for a new console infrastructure that is independent of the
console BKL, wrap the output mode into a descriptor struct so the new
infrastrucure can share the emit code that dumps the ringbuffer record
into the output text buffers.
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
include/linux/console.h | 15 +++++++
kernel/printk/printk.c | 88 ++++++++++++++++++++++++++++++-----------
2 files changed, 79 insertions(+), 24 deletions(-)
diff --git a/include/linux/console.h b/include/linux/console.h
index 05c7325e98f9..590ab62c01d9 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -187,6 +187,21 @@ struct cons_text_buf {
char text[CONSOLE_LOG_MAX];
};
+/**
+ * struct cons_outbuf_desc - console output buffer descriptor
+ * @txtbuf: Pointer to buffer for storing the text
+ * @outbuf: Pointer to the position in @buffer for
+ * writing it out to the device
+ * @len: Message length
+ * @extmsg: Select extended format printing
+ */
+struct cons_outbuf_desc {
+ struct cons_text_buf *txtbuf;
+ char *outbuf;
+ unsigned int len;
+ bool extmsg;
+};
+
/**
* struct console - The console descriptor structure
* @name: The name of the console driver
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 9cbd44e9fc45..c9207d81b90c 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2689,40 +2689,39 @@ static void __console_unlock(void)
up_console_sem();
}
-/*
- * Print one record for the given console. The record printed is whatever
- * record is the next available record for the given console.
- *
- * @text is a buffer of size CONSOLE_LOG_MAX.
- *
- * If extended messages should be printed, @ext_text is a buffer of size
- * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL.
+
+/**
+ * cons_fill_outbuf - Fill the output buffer with the next record
+ * @con: The console to print on
+ * @desc: Pointer to the output descriptor
*
- * If dropped messages should be printed, @dropped_text is a buffer of size
- * DROPPED_TEXT_MAX. Otherwise @dropped_text must be NULL.
+ * The output descriptor contains all information which is necessary
+ * to print (buffer pointer, extended format selector...).
*
- * @handover will be set to true if a printk waiter has taken over the
- * console_lock, in which case the caller is no longer holding the
- * console_lock. Otherwise it is set to false.
+ * Returns: False if there is no pending record in the ringbuffer
+ * True if there is a pending record in the ringbuffer.
*
- * Returns false if the given console has no next record to print, otherwise
- * true.
+ * When the return value is true, then the caller has to check
+ * @desc->outbuf. If not NULL it points to the first character to write to
+ * the device and @desc->len contains the length of the message.
*
- * Requires the console_lock.
+ * If it is NULL then records have been dropped or skipped and con->seq
+ * has been forwarded so the caller can try to print the next record.
*/
-static bool console_emit_next_record(struct console *con, struct cons_text_buf *txtbuf,
- bool *handover, bool extmsg)
+static bool cons_fill_outbuf(struct console *con, struct cons_outbuf_desc *desc)
{
static int panic_console_dropped;
+
+ struct cons_text_buf *txtbuf = desc->txtbuf;
struct printk_info info;
struct printk_record r;
- unsigned long flags;
char *write_text;
size_t len;
- prb_rec_init_rd(&r, &info, txtbuf->text, CONSOLE_LOG_MAX);
+ desc->outbuf = NULL;
+ desc->len = 0;
- *handover = false;
+ prb_rec_init_rd(&r, &info, txtbuf->text, CONSOLE_LOG_MAX);
if (!prb_read_valid(prb, con->seq, &r))
return false;
@@ -2739,10 +2738,10 @@ static bool console_emit_next_record(struct console *con, struct cons_text_buf *
/* Skip record that has level above the console loglevel. */
if (suppress_message_printing(r.info->level)) {
con->seq++;
- goto skip;
+ return true;
}
- if (extmsg) {
+ if (desc->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,
@@ -2752,6 +2751,47 @@ static bool console_emit_next_record(struct console *con, struct cons_text_buf *
len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time);
}
+ desc->len = len;
+ desc->outbuf = write_text;
+ return true;
+}
+
+/**
+ * console_emit_next_record - Print one record for the given console
+ * @con: The console to print on
+ * @txtbuf: Pointer to the output buffer
+ * @handover: Pointer to Handover handshake storage
+ * @extmsg: Selects extended message format
+ *
+ * The record printed is whatever record is the next available record for
+ * the given console.
+ *
+ * @handover will be set to true if a printk waiter has taken over the
+ * console_lock, in which case the caller is no longer holding the
+ * console_lock. Otherwise it is set to false.
+ *
+ * Returns false if the given console has no next record to print, otherwise
+ * true.
+ *
+ * Requires the console_lock.
+ */
+static bool console_emit_next_record(struct console *con, struct cons_text_buf *txtbuf,
+ bool *handover, bool extmsg)
+{
+ struct cons_outbuf_desc desc = {
+ .txtbuf = txtbuf,
+ .extmsg = extmsg,
+ };
+ unsigned long flags;
+
+ *handover = false;
+
+ if (!cons_fill_outbuf(con, &desc))
+ return false;
+
+ if (!desc.outbuf)
+ goto skip;
+
/*
* While actively printing out messages, if another printk()
* were to occur on another CPU, it may wait for this one to
@@ -2766,7 +2806,7 @@ static bool console_emit_next_record(struct console *con, struct cons_text_buf *
console_lock_spinning_enable();
stop_critical_timings(); /* don't trace print latency */
- call_console_driver(con, write_text, len, extmsg ? NULL : txtbuf->dropped_text);
+ call_console_driver(con, desc.outbuf, desc.len, extmsg ? NULL : txtbuf->dropped_text);
start_critical_timings();
con->seq++;
--
2.30.2
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