If for some strange reason the buffer_page gets bigger, or the page struct gets smaller, I want to know this ASAP. The best way is to not let the kernel compile. This patch adds code to test the size of the struct buffer_page against the page struct and will cause compile issues if the buffer_page ever gets bigger than the page struct. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 11 +++++++++++ 1 file changed, 11 insertions(+) Index: linux-tip.git/kernel/trace/ring_buffer.c =================================================================== --- linux-tip.git.orig/kernel/trace/ring_buffer.c 2008-09-29 17:31:05.000000000 -0400 +++ linux-tip.git/kernel/trace/ring_buffer.c 2008-09-29 19:59:24.000000000 -0400 @@ -289,6 +289,12 @@ static void rb_free_cpu_buffer(struct ri kfree(cpu_buffer); } +/* + * Causes compile errors if the struct buffer_page gets bigger + * than the struct page. + */ +extern int ring_buffer_page_too_big(void); + /** * ring_buffer_alloc - allocate a new ring_buffer * @size: the size in bytes that is needed. @@ -305,6 +311,11 @@ struct ring_buffer *ring_buffer_alloc(un int bsize; int cpu; + /* Paranoid! Optimizes out when all is well */ + if (sizeof(struct buffer_page) > sizeof(struct page)) + ring_buffer_page_too_big(); + + /* keep it in its own cache line */ buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), GFP_KERNEL); -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/