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Message-Id: <20200717234818.8622-3-john.ogness@linutronix.de>
Date: Sat, 18 Jul 2020 01:54:16 +0206
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>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] printk: store instead of processing cont parts
Instead of buffering continuous line parts before storing the full
line into the ringbuffer, store each part as its own record.
Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
kernel/printk/printk.c | 114 ++++-------------------------------------
1 file changed, 11 insertions(+), 103 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fec71229169e..c4274c867771 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -495,9 +495,14 @@ static void truncate_msg(u16 *text_len, u16 *trunc_msg_len)
*trunc_msg_len = 0;
}
+static inline u32 printk_caller_id(void)
+{
+ return in_task() ? task_pid_nr(current) :
+ 0x80000000 + raw_smp_processor_id();
+}
+
/* 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,
+static int log_store(int facility, int level, enum log_flags flags,
const char *dict, u16 dict_len,
const char *text, u16 text_len)
{
@@ -525,11 +530,8 @@ static int log_store(u32 caller_id, int facility, int level,
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;
+ r.info->ts_nsec = local_clock();
+ r.info->caller_id = printk_caller_id();
/* insert message */
prb_commit(&e);
@@ -1874,100 +1876,6 @@ static inline void printk_delay(void)
}
}
-static inline u32 printk_caller_id(void)
-{
- return in_task() ? task_pid_nr(current) :
- 0x80000000 + raw_smp_processor_id();
-}
-
-/*
- * Continuation lines are buffered, and not committed to the record buffer
- * until the line is complete, or a race forces it. The line fragments
- * though, are printed immediately to the consoles to ensure everything has
- * reached the console in case of a kernel crash.
- */
-static struct cont {
- char buf[LOG_LINE_MAX];
- size_t len; /* length == 0 means unused buffer */
- u32 caller_id; /* printk_caller_id() of first print */
- u64 ts_nsec; /* time of first print */
- u8 level; /* log level of first message */
- u8 facility; /* log facility of first message */
- enum log_flags flags; /* prefix, newline flags */
-} cont;
-
-static void cont_flush(void)
-{
- if (cont.len == 0)
- return;
-
- log_store(cont.caller_id, cont.facility, cont.level, cont.flags,
- cont.ts_nsec, NULL, 0, cont.buf, cont.len);
- cont.len = 0;
-}
-
-static bool cont_add(u32 caller_id, int facility, int level,
- enum log_flags flags, const char *text, size_t len)
-{
- /* If the line gets too long, split it up in separate records. */
- if (cont.len + len > sizeof(cont.buf)) {
- cont_flush();
- return false;
- }
-
- if (!cont.len) {
- cont.facility = facility;
- cont.level = level;
- cont.caller_id = caller_id;
- cont.ts_nsec = local_clock();
- cont.flags = flags;
- }
-
- memcpy(cont.buf + cont.len, text, len);
- cont.len += len;
-
- // The original flags come from the first line,
- // but later continuations can add a newline.
- if (flags & LOG_NEWLINE) {
- cont.flags |= LOG_NEWLINE;
- cont_flush();
- }
-
- return true;
-}
-
-static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len)
-{
- const u32 caller_id = printk_caller_id();
-
- /*
- * If an earlier line was buffered, and we're a continuation
- * write from the same context, try to add it to the buffer.
- */
- if (cont.len) {
- if (cont.caller_id == caller_id && (lflags & LOG_CONT)) {
- if (cont_add(caller_id, facility, level, lflags, text, text_len))
- return text_len;
- }
- /* Otherwise, make sure it's flushed */
- cont_flush();
- }
-
- /* Skip empty continuation lines that couldn't be added - they just flush */
- if (!text_len && (lflags & LOG_CONT))
- return 0;
-
- /* If it doesn't end in a newline, try to buffer the current line */
- if (!(lflags & LOG_NEWLINE)) {
- if (cont_add(caller_id, facility, level, lflags, text, text_len))
- return text_len;
- }
-
- /* Store it in the record log */
- return log_store(caller_id, facility, level, lflags, 0,
- dict, dictlen, text, text_len);
-}
-
/* Must be called under logbuf_lock. */
int vprintk_store(int facility, int level,
const char *dict, size_t dictlen,
@@ -2015,8 +1923,8 @@ int vprintk_store(int facility, int level,
if (dict)
lflags |= LOG_NEWLINE;
- return log_output(facility, level, lflags,
- dict, dictlen, text, text_len);
+ return log_store(facility, level, lflags, dict, dictlen,
+ text, text_len);
}
asmlinkage int vprintk_emit(int facility, int level,
--
2.20.1
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