gcc-4.6: printk: use stable variable to dump kmsg buffer

kmsg_dump takes care to sample the global variables
inside a spinlock, but then goes on to use the same
variables outside the spinlock region too.

Use the correct variable. This will make the race
window smaller.

Found by gcc 4.6's new warnings.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/printk.c b/kernel/printk.c
index 4ab0164bcf84bc9660a5802c6355817b5d015c2e..8fe465ac008aebdcdbb0e9db9fcd644d5b12c231 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1549,9 +1549,9 @@ void kmsg_dump(enum kmsg_dump_reason reason)
        chars = logged_chars;
        spin_unlock_irqrestore(&logbuf_lock, flags);
 
-       if (logged_chars > end) {
-               s1 = log_buf + log_buf_len - logged_chars + end;
-               l1 = logged_chars - end;
+       if (chars > end) {
+               s1 = log_buf + log_buf_len - chars + end;
+               l1 = chars - end;
 
                s2 = log_buf;
                l2 = end;
@@ -1559,8 +1559,8 @@ void kmsg_dump(enum kmsg_dump_reason reason)
                s1 = "";
                l1 = 0;
 
-               s2 = log_buf + end - logged_chars;
-               l2 = logged_chars;
+               s2 = log_buf + end - chars;
+               l2 = chars;
        }
 
        if (!spin_trylock_irqsave(&dump_list_lock, flags)) {