diff options
| author | Feng Tang <feng.tang@intel.com> | 2011-03-22 16:34:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-22 17:44:12 -0700 |
| commit | fe3d8ad31cf51b062bbb8a9609eeb1d0c41a7f30 (patch) | |
| tree | f0e0f85582a695d0da7bae97897835ee51a0ab09 /kernel/printk.c | |
| parent | 7bf693951a8e5f7e600a45b74d91d962a453146e (diff) | |
console: prevent registered consoles from dumping old kernel message over again
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@intel.com>
Cc: Greg KH <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/printk.c')
| -rw-r--r-- | kernel/printk.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 2b591f252e5..a53607eea6d 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -113,6 +113,11 @@ static unsigned con_start; /* Index into log_buf: next char to be sent to consol 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 @@ -476,6 +481,8 @@ static void __call_console_drivers(unsigned start, unsigned end) 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))) @@ -1230,6 +1237,11 @@ 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) @@ -1464,6 +1476,12 @@ void register_console(struct console *newcon) 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(); |