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Message-Id: <20201207222020.2923-2-john.ogness@linutronix.de>
Date: Mon, 7 Dec 2020 23:26:18 +0106
From: John Ogness <john.ogness@...utronix.de>
To: Petr Mladek <pmladek@...e.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: [PATCH next v3 1/3] printk: inline log_output(),log_store() in vprintk_store()
In preparation for removing logbuf_lock, inline log_output()
and log_store() into vprintk_store(). This will simplify dealing
with the various code branches and fallbacks that are possible.
Signed-off-by: John Ogness <john.ogness@...utronix.de>
Reviewed-by: Petr Mladek <pmladek@...e.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
kernel/printk/printk.c | 145 +++++++++++++++++++----------------------
1 file changed, 67 insertions(+), 78 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index f279d4fbd9dd..bf5fd2be3a05 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -491,52 +491,6 @@ static void truncate_msg(u16 *text_len, u16 *trunc_msg_len)
*trunc_msg_len = 0;
}
-/* insert record into the buffer, discard old ones, update heads */
-static int log_store(u32 caller_id, int facility, int level,
- enum log_flags flags, u64 ts_nsec,
- const struct dev_printk_info *dev_info,
- const char *text, u16 text_len)
-{
- struct prb_reserved_entry e;
- struct printk_record r;
- u16 trunc_msg_len = 0;
-
- prb_rec_init_wr(&r, text_len);
-
- if (!prb_reserve(&e, prb, &r)) {
- /* truncate the message if it is too long for empty buffer */
- truncate_msg(&text_len, &trunc_msg_len);
- prb_rec_init_wr(&r, text_len + trunc_msg_len);
- /* survive when the log buffer is too small for trunc_msg */
- if (!prb_reserve(&e, prb, &r))
- return 0;
- }
-
- /* fill message */
- memcpy(&r.text_buf[0], text, text_len);
- if (trunc_msg_len)
- memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len);
- r.info->text_len = text_len + trunc_msg_len;
- r.info->facility = facility;
- r.info->level = level & 7;
- r.info->flags = flags & 0x1f;
- if (ts_nsec > 0)
- r.info->ts_nsec = ts_nsec;
- else
- r.info->ts_nsec = local_clock();
- r.info->caller_id = caller_id;
- if (dev_info)
- memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info));
-
- /* A message without a trailing newline can be continued. */
- if (!(flags & LOG_NEWLINE))
- prb_commit(&e);
- else
- prb_final_commit(&e);
-
- return (text_len + trunc_msg_len);
-}
-
int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
static int syslog_action_restricted(int type)
@@ -1907,44 +1861,28 @@ static inline u32 printk_caller_id(void)
0x80000000 + raw_smp_processor_id();
}
-static size_t log_output(int facility, int level, enum log_flags lflags,
- const struct dev_printk_info *dev_info,
- char *text, size_t text_len)
-{
- const u32 caller_id = printk_caller_id();
-
- if (lflags & LOG_CONT) {
- struct prb_reserved_entry e;
- struct printk_record r;
-
- prb_rec_init_wr(&r, text_len);
- if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) {
- memcpy(&r.text_buf[r.info->text_len], text, text_len);
- r.info->text_len += text_len;
- if (lflags & LOG_NEWLINE) {
- r.info->flags |= LOG_NEWLINE;
- prb_final_commit(&e);
- } else {
- prb_commit(&e);
- }
- return text_len;
- }
- }
-
- /* Store it in the record log */
- return log_store(caller_id, facility, level, lflags, 0,
- dev_info, text, text_len);
-}
-
/* Must be called under logbuf_lock. */
int vprintk_store(int facility, int level,
const struct dev_printk_info *dev_info,
const char *fmt, va_list args)
{
+ const u32 caller_id = printk_caller_id();
static char textbuf[LOG_LINE_MAX];
- char *text = textbuf;
- size_t text_len;
+ struct prb_reserved_entry e;
enum log_flags lflags = 0;
+ struct printk_record r;
+ u16 trunc_msg_len = 0;
+ char *text = textbuf;
+ u16 text_len;
+ u64 ts_nsec;
+
+ /*
+ * Since the duration of printk() can vary depending on the message
+ * and state of the ringbuffer, grab the timestamp now so that it is
+ * close to the call of printk(). This provides a more deterministic
+ * timestamp with respect to the caller.
+ */
+ ts_nsec = local_clock();
/*
* The printf needs to come first; we need the syslog
@@ -1983,7 +1921,58 @@ int vprintk_store(int facility, int level,
if (dev_info)
lflags |= LOG_NEWLINE;
- return log_output(facility, level, lflags, dev_info, text, text_len);
+ if (lflags & LOG_CONT) {
+ prb_rec_init_wr(&r, text_len);
+ if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) {
+ memcpy(&r.text_buf[r.info->text_len], text, text_len);
+ r.info->text_len += text_len;
+
+ if (lflags & LOG_NEWLINE) {
+ r.info->flags |= LOG_NEWLINE;
+ prb_final_commit(&e);
+ } else {
+ prb_commit(&e);
+ }
+
+ return text_len;
+ }
+ }
+
+ /*
+ * Explicitly initialize the record before every prb_reserve() call.
+ * prb_reserve_in_last() and prb_reserve() purposely invalidate the
+ * structure when they fail.
+ */
+ prb_rec_init_wr(&r, text_len);
+ if (!prb_reserve(&e, prb, &r)) {
+ /* truncate the message if it is too long for empty buffer */
+ truncate_msg(&text_len, &trunc_msg_len);
+
+ prb_rec_init_wr(&r, text_len + trunc_msg_len);
+ if (!prb_reserve(&e, prb, &r))
+ return 0;
+ }
+
+ /* fill message */
+ memcpy(&r.text_buf[0], text, text_len);
+ if (trunc_msg_len)
+ memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len);
+ r.info->text_len = text_len + trunc_msg_len;
+ r.info->facility = facility;
+ r.info->level = level & 7;
+ r.info->flags = lflags & 0x1f;
+ r.info->ts_nsec = ts_nsec;
+ r.info->caller_id = caller_id;
+ if (dev_info)
+ memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info));
+
+ /* A message without a trailing newline can be continued. */
+ if (!(lflags & LOG_NEWLINE))
+ prb_commit(&e);
+ else
+ prb_final_commit(&e);
+
+ return (text_len + trunc_msg_len);
}
asmlinkage int vprintk_emit(int facility, int level,
--
2.20.1
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