On Fri, 2012-11-30 at 11:12 -0500, Steven Rostedt wrote: > From: Steven Rostedt <[email protected]> > > 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+
Hmm, quilt didn't Cc. Grumble, I think a system update of quilt removed my modification to not have quilt get confused by the hash symbol :-( -- Steve > Signed-off-by: Steven Rostedt <[email protected]> > --- > kernel/trace/ring_buffer.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index b979426..ec01803 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -1396,6 +1396,8 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) > struct list_head *head_page_with_bit; > > head_page = &rb_set_head_page(cpu_buffer)->list; > + if (!head_page) > + break; > prev_page = head_page->prev; > > first_page = pages->next; > @@ -2934,7 +2936,7 @@ unsigned long ring_buffer_oldest_event_ts(struct > ring_buffer *buffer, int cpu) > unsigned long flags; > struct ring_buffer_per_cpu *cpu_buffer; > struct buffer_page *bpage; > - unsigned long ret; > + unsigned long ret = 0; > > if (!cpumask_test_cpu(cpu, buffer->cpumask)) > return 0; > @@ -2949,7 +2951,8 @@ unsigned long ring_buffer_oldest_event_ts(struct > ring_buffer *buffer, int cpu) > bpage = cpu_buffer->reader_page; > else > bpage = rb_set_head_page(cpu_buffer); > - ret = bpage->page->time_stamp; > + if (bpage) > + ret = bpage->page->time_stamp; > raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); > > return ret; > @@ -3260,6 +3263,8 @@ rb_get_reader_page(struct ring_buffer_per_cpu > *cpu_buffer) > * 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/
