[PATCH] Add printk_clock()

ia64's sched_clock() accesses per-cpu data which isn't set up at boot time.
Hence ia64 cannot use printk timestamping, because printk() will crash in
sched_clock().

So make printk() use printk_clock(), defaulting to sched_clock(), overrideable
by the architecture via attribute(weak).

Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index a967605bc2e3..4b8f0f9230a4 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -488,6 +488,11 @@ static int __init printk_time_setup(char *str)
 
 __setup("time", printk_time_setup);
 
+__attribute__((weak)) unsigned long long printk_clock(void)
+{
+        return sched_clock();
+}
+
 /*
  * This is printk.  It can be called from any context.  We want it to work.
  * 
@@ -565,7 +570,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                                         loglev_char = default_message_loglevel
                                                 + '0';
                                 }
-                                t = sched_clock();
+                                t = printk_clock();
                                 nanosec_rem = do_div(t, 1000000000);
                                 tlen = sprintf(tbuf,
                                                 "<%c>[%5lu.%06lu] ",