gcc-4.6: printk: use stable variable to dump kmsg buffer (8c4af38e) · Commits · 戴 / test

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>

kernel/printk.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -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)) {

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