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ring-buffer: replace most bug ons with warn on and disable buffer
This patch replaces most of the BUG_ONs in the ring_buffer code with RB_WARN_ON variants. It adds some more variants as needed for the replacement. This lets the buffer die nicely and still warn the user. One BUG_ON remains in the code, and that is because it detects a bad pointer passed in by the calling function, and not a bug by the ring buffer code itself. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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5aa1ba6a6c
commit
f536aafc5a
1 changed files with 49 additions and 16 deletions
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@ -188,6 +188,7 @@ struct ring_buffer_iter {
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u64 read_stamp;
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};
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/* buffer may be either ring_buffer or ring_buffer_per_cpu */
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#define RB_WARN_ON(buffer, cond) \
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do { \
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if (unlikely(cond)) { \
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@ -197,6 +198,15 @@ struct ring_buffer_iter {
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} while (0)
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#define RB_WARN_ON_RET(buffer, cond) \
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do { \
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if (unlikely(cond)) { \
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atomic_inc(&buffer->record_disabled); \
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WARN_ON(1); \
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return; \
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} \
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} while (0)
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#define RB_WARN_ON_RET_INT(buffer, cond) \
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do { \
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if (unlikely(cond)) { \
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atomic_inc(&buffer->record_disabled); \
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@ -205,6 +215,15 @@ struct ring_buffer_iter {
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} \
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} while (0)
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#define RB_WARN_ON_RET_NULL(buffer, cond) \
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do { \
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if (unlikely(cond)) { \
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atomic_inc(&buffer->record_disabled); \
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WARN_ON(1); \
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return NULL; \
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} \
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} while (0)
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#define RB_WARN_ON_ONCE(buffer, cond) \
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do { \
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static int once; \
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@ -215,6 +234,17 @@ struct ring_buffer_iter {
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} \
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} while (0)
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/* buffer must be ring_buffer not per_cpu */
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#define RB_WARN_ON_UNLOCK(buffer, cond) \
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do { \
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if (unlikely(cond)) { \
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mutex_unlock(&buffer->mutex); \
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atomic_inc(&buffer->record_disabled); \
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WARN_ON(1); \
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return -1; \
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} \
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} while (0)
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/**
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* check_pages - integrity check of buffer pages
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* @cpu_buffer: CPU buffer with pages to test
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@ -227,13 +257,13 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
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struct list_head *head = &cpu_buffer->pages;
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struct buffer_page *page, *tmp;
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RB_WARN_ON_RET(cpu_buffer, head->next->prev != head);
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RB_WARN_ON_RET(cpu_buffer, head->prev->next != head);
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RB_WARN_ON_RET_INT(cpu_buffer, head->next->prev != head);
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RB_WARN_ON_RET_INT(cpu_buffer, head->prev->next != head);
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list_for_each_entry_safe(page, tmp, head, list) {
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RB_WARN_ON_RET(cpu_buffer,
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RB_WARN_ON_RET_INT(cpu_buffer,
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page->list.next->prev != &page->list);
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RB_WARN_ON_RET(cpu_buffer,
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RB_WARN_ON_RET_INT(cpu_buffer,
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page->list.prev->next != &page->list);
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}
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@ -440,13 +470,13 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
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synchronize_sched();
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for (i = 0; i < nr_pages; i++) {
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BUG_ON(list_empty(&cpu_buffer->pages));
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RB_WARN_ON_RET(cpu_buffer, list_empty(&cpu_buffer->pages));
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p = cpu_buffer->pages.next;
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page = list_entry(p, struct buffer_page, list);
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list_del_init(&page->list);
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free_buffer_page(page);
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}
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BUG_ON(list_empty(&cpu_buffer->pages));
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RB_WARN_ON_RET(cpu_buffer, list_empty(&cpu_buffer->pages));
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rb_reset_cpu(cpu_buffer);
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@ -468,7 +498,7 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
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synchronize_sched();
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for (i = 0; i < nr_pages; i++) {
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BUG_ON(list_empty(pages));
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RB_WARN_ON_RET(cpu_buffer, list_empty(pages));
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p = pages->next;
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page = list_entry(p, struct buffer_page, list);
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list_del_init(&page->list);
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@ -523,7 +553,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
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if (size < buffer_size) {
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/* easy case, just free pages */
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BUG_ON(nr_pages >= buffer->pages);
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RB_WARN_ON_UNLOCK(buffer, nr_pages >= buffer->pages);
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rm_pages = buffer->pages - nr_pages;
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@ -542,7 +572,8 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
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* add these pages to the cpu_buffers. Otherwise we just free
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* them all and return -ENOMEM;
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*/
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BUG_ON(nr_pages <= buffer->pages);
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RB_WARN_ON_UNLOCK(buffer, nr_pages <= buffer->pages);
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new_pages = nr_pages - buffer->pages;
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for_each_buffer_cpu(buffer, cpu) {
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@ -565,7 +596,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
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rb_insert_pages(cpu_buffer, &pages, new_pages);
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}
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BUG_ON(!list_empty(&pages));
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RB_WARN_ON_UNLOCK(buffer, !list_empty(&pages));
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out:
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buffer->pages = nr_pages;
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@ -653,7 +684,7 @@ static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer)
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head += rb_event_length(event)) {
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event = __rb_page_index(cpu_buffer->head_page, head);
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BUG_ON(rb_null_event(event));
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RB_WARN_ON_RET(cpu_buffer, rb_null_event(event));
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/* Only count data entries */
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if (event->type != RINGBUF_TYPE_DATA)
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continue;
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@ -940,7 +971,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
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/* We reserved something on the buffer */
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BUG_ON(write > BUF_PAGE_SIZE);
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RB_WARN_ON_RET_NULL(cpu_buffer, write > BUF_PAGE_SIZE);
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event = __rb_page_index(tail_page, tail);
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rb_update_event(event, type, length);
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@ -1621,7 +1652,7 @@ static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer)
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reader = rb_get_reader_page(cpu_buffer);
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/* This function should not be called when buffer is empty */
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BUG_ON(!reader);
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RB_WARN_ON_RET(cpu_buffer, !reader);
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event = rb_reader_event(cpu_buffer);
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@ -1648,7 +1679,8 @@ static void rb_advance_iter(struct ring_buffer_iter *iter)
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* Check if we are at the end of the buffer.
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*/
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if (iter->head >= rb_page_size(iter->head_page)) {
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BUG_ON(iter->head_page == cpu_buffer->commit_page);
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RB_WARN_ON_RET(buffer,
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iter->head_page == cpu_buffer->commit_page);
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rb_inc_iter(iter);
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return;
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}
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@ -1661,8 +1693,9 @@ static void rb_advance_iter(struct ring_buffer_iter *iter)
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* This should not be called to advance the header if we are
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* at the tail of the buffer.
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*/
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BUG_ON((iter->head_page == cpu_buffer->commit_page) &&
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(iter->head + length > rb_commit_index(cpu_buffer)));
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RB_WARN_ON_RET(cpu_buffer,
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(iter->head_page == cpu_buffer->commit_page) &&
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(iter->head + length > rb_commit_index(cpu_buffer)));
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rb_update_iter_read_stamp(iter, event);
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