The function rb_set_head_page() searches the list of ring buffer pages for a the page that has the HEAD page flag set. If it does not find it, it will do a WARN_ON(), disable the ring buffer and return NULL, as this should never happen.
But if this bug happens to happen, not all callers of this function can handle a NULL pointer being returned from it. That needs to be fixed. Cc: [email protected] # 3.0+ Signed-off-by: Steven Rostedt <[email protected]> --- kernel/trace/ring_buffer.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) Index: linux-test.git/kernel/trace/ring_buffer.c =================================================================== --- linux-test.git.orig/kernel/trace/ring_buffer.c +++ linux-test.git/kernel/trace/ring_buffer.c @@ -2926,6 +2926,8 @@ rb_get_reader_page(struct ring_buffer_pe * Splice the empty reader page into the list around the head. */ reader = rb_set_head_page(cpu_buffer); + if (!reader) + goto out; cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); cpu_buffer->reader_page->list.prev = reader->list.prev; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
