diff options
| -rw-r--r-- | kernel/trace/trace.c | 103 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 6 |
2 files changed, 65 insertions, 44 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6580e7ed04be..777b859e1c2e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -176,10 +176,9 @@ flip_trace(struct trace_array_cpu *tr1, struct trace_array_cpu *tr2) INIT_LIST_HEAD(&flip_pages); - tr1->trace_current = NULL; - memcpy(&tr1->trace_current_idx, &tr2->trace_current_idx, + memcpy(&tr1->trace_head_idx, &tr2->trace_head_idx, sizeof(struct trace_array_cpu) - - offsetof(struct trace_array_cpu, trace_current_idx)); + offsetof(struct trace_array_cpu, trace_head_idx)); check_pages(tr1); check_pages(tr2); @@ -228,7 +227,6 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) tracing_reset(max_tr.data[i]); flip_trace(max_tr.data[cpu], data); - tracing_reset(data); __update_max_tr(tr, tsk, cpu); @@ -343,9 +341,9 @@ void unregister_tracer(struct tracer *type) notrace void tracing_reset(struct trace_array_cpu *data) { data->trace_idx = 0; - data->trace_current = head_page(data); - data->trace_current_idx = 0; - data->time_offset = 0; + data->trace_head = data->trace_tail = head_page(data); + data->trace_head_idx = 0; + data->trace_tail_idx = 0; } #ifdef CONFIG_FTRACE @@ -470,38 +468,65 @@ notrace void tracing_record_cmdline(struct task_struct *tsk) trace_save_cmdline(tsk); } +static inline notrace struct list_head * +trace_next_list(struct trace_array_cpu *data, struct list_head *next) +{ + /* + * Roundrobin - but skip the head (which is not a real page): + */ + next = next->next; + if (unlikely(next == &data->trace_pages)) + next = next->next; + BUG_ON(next == &data->trace_pages); + + return next; +} + +static inline notrace void * +trace_next_page(struct trace_array_cpu *data, void *addr) +{ + struct list_head *next; + struct page *page; + + page = virt_to_page(addr); + + next = trace_next_list(data, &page->lru); + page = list_entry(next, struct page, lru); + + return page_address(page); +} + static inline notrace struct trace_entry * tracing_get_trace_entry(struct trace_array *tr, struct trace_array_cpu *data) { unsigned long idx, idx_next; struct trace_entry *entry; - struct list_head *next; - struct page *page; data->trace_idx++; - idx = data->trace_current_idx; + idx = data->trace_head_idx; idx_next = idx + 1; BUG_ON(idx * TRACE_ENTRY_SIZE >= PAGE_SIZE); - entry = data->trace_current + idx * TRACE_ENTRY_SIZE; + entry = data->trace_head + idx * TRACE_ENTRY_SIZE; if (unlikely(idx_next >= ENTRIES_PER_PAGE)) { - page = virt_to_page(data->trace_current); - /* - * Roundrobin - but skip the head (which is not a real page): - */ - next = page->lru.next; - if (unlikely(next == &data->trace_pages)) - next = next->next; - BUG_ON(next == &data->trace_pages); - - page = list_entry(next, struct page, lru); - data->trace_current = page_address(page); + data->trace_head = trace_next_page(data, data->trace_head); idx_next = 0; } - data->trace_current_idx = idx_next; + if (data->trace_head == data->trace_tail && + idx_next == data->trace_tail_idx) { + /* overrun */ + data->trace_tail_idx++; + if (data->trace_tail_idx >= ENTRIES_PER_PAGE) { + data->trace_tail = + trace_next_page(data, data->trace_tail); + data->trace_tail_idx = 0; + } + } + + data->trace_head_idx = idx_next; return entry; } @@ -571,21 +596,11 @@ trace_entry_idx(struct trace_array *tr, struct trace_array_cpu *data, return NULL; if (!iter->next_page[cpu]) { - /* - * Initialize. If the count of elements in - * this buffer is greater than the max entries - * we had an underrun. Which means we looped around. - * We can simply use the current pointer as our - * starting point. - */ - if (data->trace_idx >= tr->entries) { - page = virt_to_page(data->trace_current); - iter->next_page[cpu] = &page->lru; - iter->next_page_idx[cpu] = data->trace_current_idx; - } else { - iter->next_page[cpu] = data->trace_pages.next; - iter->next_page_idx[cpu] = 0; - } + /* Initialize the iterator for this cpu trace buffer */ + WARN_ON(!data->trace_tail); + page = virt_to_page(data->trace_tail); + iter->next_page[cpu] = &page->lru; + iter->next_page_idx[cpu] = data->trace_tail_idx; } page = list_entry(iter->next_page[cpu], struct page, lru); @@ -593,6 +608,12 @@ trace_entry_idx(struct trace_array *tr, struct trace_array_cpu *data, array = page_address(page); + /* Still possible to catch up to the tail */ + if (iter->next_idx[cpu] && array == data->trace_tail && + iter->next_page_idx[cpu] == data->trace_tail_idx) + return NULL; + + WARN_ON(iter->next_page_idx[cpu] >= ENTRIES_PER_PAGE); return &array[iter->next_page_idx[cpu]]; } @@ -638,10 +659,8 @@ static void *find_next_entry_inc(struct trace_iterator *iter) iter->next_page_idx[next_cpu] = 0; iter->next_page[next_cpu] = - iter->next_page[next_cpu]->next; - if (iter->next_page[next_cpu] == &data->trace_pages) - iter->next_page[next_cpu] = - data->trace_pages.next; + trace_next_list(data, iter->next_page[next_cpu]); + } } iter->prev_ent = iter->ent; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 5df8ff2b84a7..0ce127455b4b 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -53,13 +53,15 @@ struct trace_entry { * the trace, etc.) */ struct trace_array_cpu { - void *trace_current; struct list_head trace_pages; atomic_t disabled; cycle_t time_offset; /* these fields get copied into max-trace: */ - unsigned trace_current_idx; + unsigned trace_head_idx; + unsigned trace_tail_idx; + void *trace_head; /* producer */ + void *trace_tail; /* consumer */ unsigned long trace_idx; unsigned long saved_latency; unsigned long critical_start; |