The patch titled
console: prevent registered consoles from dumping old kernel message over again
has been added to the -mm tree. Its filename is
console-prevent-registered-consoles-from-dumping-old-kernel-message-over-again.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: console: prevent registered consoles from dumping old kernel message over again
From: Feng Tang <feng.tang@xxxxxxxxx>
For a platform with many consoles like:
"console=tty1 console=ttyMFD2 console=ttyS0 earlyprintk=mrst"
Each time when the non "selected_console" (tty1 and ttyMFD2 here) get
registered, the existing kernel message will be printed out on registered
consoles again, the "mrst" early console will get some same message for 3
times, and "tty1" will get some for twice.
As suggested by Andrew Morton, every time a new console is registered, it
will be set as the "exclusive" console which will dump the already
existing kernel messages.
Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
Cc: Greg KH <gregkh@xxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff -puN kernel/printk.c~console-prevent-registered-consoles-from-dumping-old-kernel-message-over-again kernel/printk.c
--- a/kernel/printk.c~console-prevent-registered-consoles-from-dumping-old-kernel-message-over-again
+++ a/kernel/printk.c
@@ -113,6 +113,11 @@ static unsigned con_start; /* Index into
static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */
/*
+ * If exclusive_console is non-NULL then only this console is to be printed to.
+ */
+static struct console *exclusive_console;
+
+/*
* Array of consoles built from command line options (console=)
*/
struct console_cmdline
@@ -460,6 +465,8 @@ static void __call_console_drivers(unsig
struct console *con;
for_each_console(con) {
+ if (exclusive_console && con != exclusive_console)
+ continue;
if ((con->flags & CON_ENABLED) && con->write &&
(cpu_online(smp_processor_id()) ||
(con->flags & CON_ANYTIME)))
@@ -1144,6 +1151,11 @@ void console_unlock(void)
local_irq_restore(flags);
}
console_locked = 0;
+
+ /* Release the exclusive_console once it is used */
+ if (unlikely(exclusive_console))
+ exclusive_console = NULL;
+
up(&console_sem);
spin_unlock_irqrestore(&logbuf_lock, flags);
if (wake_klogd)
@@ -1378,6 +1390,12 @@ void register_console(struct console *ne
spin_lock_irqsave(&logbuf_lock, flags);
con_start = log_start;
spin_unlock_irqrestore(&logbuf_lock, flags);
+ /*
+ * We're about to replay the log buffer. Only do this to the
+ * just-registered console to avoid excessive message spam to
+ * the already-registered consoles.
+ */
+ exclusive_console = newcon;
}
console_unlock();
console_sysfs_notify();
_
Patches currently in -mm which might be from feng.tang@xxxxxxxxx are
console-prevent-registered-consoles-from-dumping-old-kernel-message-over-again.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
