perf fixes for v3.8
Subsystems (3)
Linus,
Please pull the latest perf-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-for-linus
HEAD: 08cd2a6960ae2e1aa7f44b44ebafa84f503a2dd1 Merge branch 'tip/perf/urgent-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/urgent
These are late-v3.7 pending fixes for tracing.
Thanks,
Ingo
------------------>
Dan Carpenter (1):
ftrace: Clear bits properly in reset_iter_read()
Steven Rostedt (2):
ring-buffer: Fix NULL pointer if rb_set_head_page() fails
ring-buffer: Fix race between integrity check and readers
kernel/trace/ftrace.c | 2 +- kernel/trace/ring_buffer.c | 16 +++++++++++++--- 2 files changed, 14 insertions(+), 4 deletions(-)
kernel/trace/ftrace.c +1 -1
@@ -2437,7 +2437,7 @@ static void reset_iter_read(struct ftrace_iterator *iter) { iter->pos =0 ; iter->func_pos =0 ; - iter->flags &= ~(FTRACE_ITER_PRINTALL &FTRACE_ITER_HASH ); + iter->flags &= ~(FTRACE_ITER_PRINTALL |FTRACE_ITER_HASH ); }static void *t_start (struct seq_file *m,loff_t *pos)
kernel/trace/ring_buffer.c +13 -3
@@ -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;
@@ -3778,12 +3783,17 @@ void ring_buffer_read_finish(struct ring_buffer_iter *iter) {struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; +unsigned long flags;/* * Ring buffer is disabled from recording, here's a good place -* to check the integrity of the ring buffer. +* to check the integrity of the ring buffer. +* Must prevent readers from trying to read, as the check +* clears the HEAD page and readers require it. */ +raw_spin_lock_irqsave (&cpu_buffer->reader_lock, flags);rb_check_pages (cpu_buffer); +raw_spin_unlock_irqrestore (&cpu_buffer->reader_lock, flags);atomic_dec (&cpu_buffer->record_disabled);atomic_dec (&cpu_buffer->buffer->resize_disabled);