diff options
| author | Wolfram Sang <wsa@kernel.org> | 2023-04-24 12:50:20 +0200 |
|---|---|---|
| committer | Wolfram Sang <wsa@kernel.org> | 2023-04-24 12:50:20 +0200 |
| commit | 38c87827ffd3c7e1dd61eee9a7dea13d487dc2ed (patch) | |
| tree | e6bd1c3ae56823874a736c1512409c123c9a4219 /kernel/trace/ring_buffer.c | |
| parent | 9496fffcb28f39e0352779a0199b6e61861c9221 (diff) | |
| parent | d663d93bb47e7ab45602b227701022d8aa16040a (diff) | |
Merge branch 'i2c/for-current' into i2c/for-mergewindow
This should have been in 6.3, but sadly I missed it.
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index af50d931b020..76a2d91eecad 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -354,10 +354,6 @@ static void rb_init_page(struct buffer_data_page *bpage) local_set(&bpage->commit, 0); } -/* - * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing - * this issue out. - */ static void free_buffer_page(struct buffer_page *bpage) { free_page((unsigned long)bpage->page); @@ -3102,6 +3098,10 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) if (RB_WARN_ON(cpu_buffer, rb_is_reader_page(cpu_buffer->tail_page))) return; + /* + * No need for a memory barrier here, as the update + * of the tail_page did it for this page. + */ local_set(&cpu_buffer->commit_page->page->commit, rb_page_write(cpu_buffer->commit_page)); rb_inc_page(&cpu_buffer->commit_page); @@ -3111,6 +3111,8 @@ rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) while (rb_commit_index(cpu_buffer) != rb_page_write(cpu_buffer->commit_page)) { + /* Make sure the readers see the content of what is committed. */ + smp_wmb(); local_set(&cpu_buffer->commit_page->page->commit, rb_page_write(cpu_buffer->commit_page)); RB_WARN_ON(cpu_buffer, @@ -4688,7 +4690,12 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) /* * Make sure we see any padding after the write update - * (see rb_reset_tail()) + * (see rb_reset_tail()). + * + * In addition, a writer may be writing on the reader page + * if the page has not been fully filled, so the read barrier + * is also needed to make sure we see the content of what is + * committed by the writer (see rb_set_commit_to_write()). */ smp_rmb(); |