ring-buffer: clean up warn ons

Impact: Restructure WARN_ONs in ring_buffer.c

The current WARN_ON macros in ring_buffer.c are quite ugly.

This patch cleans them up and uses a single RB_WARN_ON that returns
the value of the condition. This allows the caller to abort the
function if the condition is true.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 17c2cce..8c5cacb 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -191,60 +191,14 @@ struct ring_buffer_iter {
 
 /* buffer may be either ring_buffer or ring_buffer_per_cpu */
 #define RB_WARN_ON(buffer, cond)                               \
-       do {                                                    \
-               if (unlikely(cond)) {                           \
+       ({                                                      \
+               int _____ret = unlikely(cond);                  \
+               if (_____ret) {                                 \
                        atomic_inc(&buffer->record_disabled);   \
                        WARN_ON(1);                             \
                }                                               \
-       } while (0)
-
-#define RB_WARN_ON_RET(buffer, cond)                           \
-       do {                                                    \
-               if (unlikely(cond)) {                           \
-                       atomic_inc(&buffer->record_disabled);   \
-                       WARN_ON(1);                             \
-                       return;                                 \
-               }                                               \
-       } while (0)
-
-#define RB_WARN_ON_RET_INT(buffer, cond)                       \
-       do {                                                    \
-               if (unlikely(cond)) {                           \
-                       atomic_inc(&buffer->record_disabled);   \
-                       WARN_ON(1);                             \
-                       return -1;                              \
-               }                                               \
-       } while (0)
-
-#define RB_WARN_ON_RET_NULL(buffer, cond)                      \
-       do {                                                    \
-               if (unlikely(cond)) {                           \
-                       atomic_inc(&buffer->record_disabled);   \
-                       WARN_ON(1);                             \
-                       return NULL;                            \
-               }                                               \
-       } while (0)
-
-#define RB_WARN_ON_ONCE(buffer, cond)                          \
-       do {                                                    \
-               static int once;                                \
-               if (unlikely(cond) && !once) {                  \
-                       once++;                                 \
-                       atomic_inc(&buffer->record_disabled);   \
-                       WARN_ON(1);                             \
-               }                                               \
-       } while (0)
-
-/* buffer must be ring_buffer not per_cpu */
-#define RB_WARN_ON_UNLOCK(buffer, cond)                                \
-       do {                                                    \
-               if (unlikely(cond)) {                           \
-                       mutex_unlock(&buffer->mutex);           \
-                       atomic_inc(&buffer->record_disabled);   \
-                       WARN_ON(1);                             \
-                       return -1;                              \
-               }                                               \
-       } while (0)
+               _____ret;                                       \
+       })
 
 /**
  * check_pages - integrity check of buffer pages
@@ -258,14 +212,18 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
        struct list_head *head = &cpu_buffer->pages;
        struct buffer_page *page, *tmp;
 
-       RB_WARN_ON_RET_INT(cpu_buffer, head->next->prev != head);
-       RB_WARN_ON_RET_INT(cpu_buffer, head->prev->next != head);
+       if (RB_WARN_ON(cpu_buffer, head->next->prev != head))
+               return -1;
+       if (RB_WARN_ON(cpu_buffer, head->prev->next != head))
+               return -1;
 
        list_for_each_entry_safe(page, tmp, head, list) {
-               RB_WARN_ON_RET_INT(cpu_buffer,
-                              page->list.next->prev != &page->list);
-               RB_WARN_ON_RET_INT(cpu_buffer,
-                              page->list.prev->next != &page->list);
+               if (RB_WARN_ON(cpu_buffer,
+                              page->list.next->prev != &page->list))
+                       return -1;
+               if (RB_WARN_ON(cpu_buffer,
+                              page->list.prev->next != &page->list))
+                       return -1;
        }
 
        return 0;
@@ -472,13 +430,15 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages)
        synchronize_sched();
 
        for (i = 0; i < nr_pages; i++) {
-               RB_WARN_ON_RET(cpu_buffer, list_empty(&cpu_buffer->pages));
+               if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages)))
+                       return;
                p = cpu_buffer->pages.next;
                page = list_entry(p, struct buffer_page, list);
                list_del_init(&page->list);
                free_buffer_page(page);
        }
-       RB_WARN_ON_RET(cpu_buffer, list_empty(&cpu_buffer->pages));
+       if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages)))
+               return;
 
        rb_reset_cpu(cpu_buffer);
 
@@ -500,7 +460,8 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer,
        synchronize_sched();
 
        for (i = 0; i < nr_pages; i++) {
-               RB_WARN_ON_RET(cpu_buffer, list_empty(pages));
+               if (RB_WARN_ON(cpu_buffer, list_empty(pages)))
+                       return;
                p = pages->next;
                page = list_entry(p, struct buffer_page, list);
                list_del_init(&page->list);
@@ -555,7 +516,10 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
        if (size < buffer_size) {
 
                /* easy case, just free pages */
-               RB_WARN_ON_UNLOCK(buffer, nr_pages >= buffer->pages);
+               if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) {
+                       mutex_unlock(&buffer->mutex);
+                       return -1;
+               }
 
                rm_pages = buffer->pages - nr_pages;
 
@@ -574,7 +538,10 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
         * add these pages to the cpu_buffers. Otherwise we just free
         * them all and return -ENOMEM;
         */
-       RB_WARN_ON_UNLOCK(buffer, nr_pages <= buffer->pages);
+       if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) {
+               mutex_unlock(&buffer->mutex);
+               return -1;
+       }
 
        new_pages = nr_pages - buffer->pages;
 
@@ -598,7 +565,10 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
                rb_insert_pages(cpu_buffer, &pages, new_pages);
        }
 
-       RB_WARN_ON_UNLOCK(buffer, !list_empty(&pages));
+       if (RB_WARN_ON(buffer, !list_empty(&pages))) {
+               mutex_unlock(&buffer->mutex);
+               return -1;
+       }
 
  out:
        buffer->pages = nr_pages;
@@ -686,7 +656,8 @@ static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer)
             head += rb_event_length(event)) {
 
                event = __rb_page_index(cpu_buffer->head_page, head);
-               RB_WARN_ON_RET(cpu_buffer, rb_null_event(event));
+               if (RB_WARN_ON(cpu_buffer, rb_null_event(event)))
+                       return;
                /* Only count data entries */
                if (event->type != RINGBUF_TYPE_DATA)
                        continue;
@@ -739,8 +710,9 @@ rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer,
        addr &= PAGE_MASK;
 
        while (cpu_buffer->commit_page->page != (void *)addr) {
-               RB_WARN_ON(cpu_buffer,
-                          cpu_buffer->commit_page == cpu_buffer->tail_page);
+               if (RB_WARN_ON(cpu_buffer,
+                         cpu_buffer->commit_page == cpu_buffer->tail_page))
+                       return;
                cpu_buffer->commit_page->commit =
                        cpu_buffer->commit_page->write;
                rb_inc_page(cpu_buffer, &cpu_buffer->commit_page);
@@ -896,7 +868,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                reader_page = cpu_buffer->reader_page;
 
                /* we grabbed the lock before incrementing */
-               RB_WARN_ON(cpu_buffer, next_page == reader_page);
+               if (RB_WARN_ON(cpu_buffer, next_page == reader_page))
+                       goto out_unlock;
 
                /*
                 * If for some reason, we had an interrupt storm that made
@@ -973,7 +946,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 
        /* We reserved something on the buffer */
 
-       RB_WARN_ON_RET_NULL(cpu_buffer, write > BUF_PAGE_SIZE);
+       if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE))
+               return NULL;
 
        event = __rb_page_index(tail_page, tail);
        rb_update_event(event, type, length);
@@ -1072,10 +1046,8 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
         * storm or we have something buggy.
         * Bail!
         */
-       if (unlikely(++nr_loops > 1000)) {
-               RB_WARN_ON(cpu_buffer, 1);
+       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
                return NULL;
-       }
 
        ts = ring_buffer_time_stamp(cpu_buffer->cpu);
 
@@ -1591,8 +1563,7 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
         * a case where we will loop three times. There should be no
         * reason to loop four times (that I know of).
         */
-       if (unlikely(++nr_loops > 3)) {
-               RB_WARN_ON(cpu_buffer, 1);
+       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) {
                reader = NULL;
                goto out;
        }
@@ -1604,8 +1575,9 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
                goto out;
 
        /* Never should we have an index greater than the size */
-       RB_WARN_ON(cpu_buffer,
-                  cpu_buffer->reader_page->read > rb_page_size(reader));
+       if (RB_WARN_ON(cpu_buffer,
+                      cpu_buffer->reader_page->read > rb_page_size(reader)))
+               goto out;
 
        /* check if we caught up to the tail */
        reader = NULL;
@@ -1659,7 +1631,8 @@ static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer)
        reader = rb_get_reader_page(cpu_buffer);
 
        /* This function should not be called when buffer is empty */
-       RB_WARN_ON_RET(cpu_buffer, !reader);
+       if (RB_WARN_ON(cpu_buffer, !reader))
+               return;
 
        event = rb_reader_event(cpu_buffer);
 
@@ -1686,8 +1659,9 @@ static void rb_advance_iter(struct ring_buffer_iter *iter)
         * Check if we are at the end of the buffer.
         */
        if (iter->head >= rb_page_size(iter->head_page)) {
-               RB_WARN_ON_RET(buffer,
-                              iter->head_page == cpu_buffer->commit_page);
+               if (RB_WARN_ON(buffer,
+                              iter->head_page == cpu_buffer->commit_page))
+                       return;
                rb_inc_iter(iter);
                return;
        }
@@ -1700,9 +1674,10 @@ static void rb_advance_iter(struct ring_buffer_iter *iter)
         * This should not be called to advance the header if we are
         * at the tail of the buffer.
         */
-       RB_WARN_ON_RET(cpu_buffer,
+       if (RB_WARN_ON(cpu_buffer,
                       (iter->head_page == cpu_buffer->commit_page) &&
-                      (iter->head + length > rb_commit_index(cpu_buffer)));
+                      (iter->head + length > rb_commit_index(cpu_buffer))))
+               return;
 
        rb_update_iter_read_stamp(iter, event);
 
@@ -1736,10 +1711,8 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
         * can have.  Nesting 10 deep of interrupts is clearly
         * an anomaly.
         */
-       if (unlikely(++nr_loops > 10)) {
-               RB_WARN_ON(cpu_buffer, 1);
+       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10))
                return NULL;
-       }
 
        reader = rb_get_reader_page(cpu_buffer);
        if (!reader)
@@ -1800,10 +1773,8 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
         * can have. Nesting 10 deep of interrupts is clearly
         * an anomaly.
         */
-       if (unlikely(++nr_loops > 10)) {
-               RB_WARN_ON(cpu_buffer, 1);
+       if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10))
                return NULL;
-       }
 
        if (rb_per_cpu_empty(cpu_buffer))
                return NULL;