Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tracing, ring-buffer: add paranoid checks for loops ftrace: use kretprobe trampoline name to test in output tracing, alpha: undefined reference to `save_stack_trace'
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commit
457d2ee225
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@ -25,7 +25,7 @@ config TRACING
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bool
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select DEBUG_FS
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select RING_BUFFER
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select STACKTRACE
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select STACKTRACE if STACKTRACE_SUPPORT
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select TRACEPOINTS
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select NOP_TRACER
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@ -1022,8 +1022,23 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
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struct ring_buffer_event *event;
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u64 ts, delta;
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int commit = 0;
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int nr_loops = 0;
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again:
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/*
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* We allow for interrupts to reenter here and do a trace.
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* If one does, it will cause this original code to loop
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* back here. Even with heavy interrupts happening, this
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* should only happen a few times in a row. If this happens
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* 1000 times in a row, there must be either an interrupt
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* storm or we have something buggy.
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* Bail!
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*/
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if (unlikely(++nr_loops > 1000)) {
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RB_WARN_ON(cpu_buffer, 1);
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return NULL;
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}
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ts = ring_buffer_time_stamp(cpu_buffer->cpu);
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/*
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@ -1532,10 +1547,23 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
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{
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struct buffer_page *reader = NULL;
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unsigned long flags;
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int nr_loops = 0;
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spin_lock_irqsave(&cpu_buffer->lock, flags);
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again:
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/*
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* This should normally only loop twice. But because the
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* start of the reader inserts an empty page, it causes
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* a case where we will loop three times. There should be no
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* reason to loop four times (that I know of).
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*/
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if (unlikely(++nr_loops > 3)) {
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RB_WARN_ON(cpu_buffer, 1);
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reader = NULL;
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goto out;
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}
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reader = cpu_buffer->reader_page;
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/* If there's more to read, return this page */
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@ -1665,6 +1693,7 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
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struct ring_buffer_per_cpu *cpu_buffer;
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struct ring_buffer_event *event;
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struct buffer_page *reader;
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int nr_loops = 0;
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if (!cpu_isset(cpu, buffer->cpumask))
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return NULL;
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@ -1672,6 +1701,19 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
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cpu_buffer = buffer->buffers[cpu];
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again:
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/*
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* We repeat when a timestamp is encountered. It is possible
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* to get multiple timestamps from an interrupt entering just
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* as one timestamp is about to be written. The max times
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* that this can happen is the number of nested interrupts we
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* can have. Nesting 10 deep of interrupts is clearly
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* an anomaly.
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*/
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if (unlikely(++nr_loops > 10)) {
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RB_WARN_ON(cpu_buffer, 1);
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return NULL;
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}
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reader = rb_get_reader_page(cpu_buffer);
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if (!reader)
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return NULL;
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@ -1722,6 +1764,7 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
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struct ring_buffer *buffer;
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struct ring_buffer_per_cpu *cpu_buffer;
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struct ring_buffer_event *event;
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int nr_loops = 0;
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if (ring_buffer_iter_empty(iter))
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return NULL;
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@ -1730,6 +1773,19 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
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buffer = cpu_buffer->buffer;
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again:
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/*
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* We repeat when a timestamp is encountered. It is possible
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* to get multiple timestamps from an interrupt entering just
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* as one timestamp is about to be written. The max times
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* that this can happen is the number of nested interrupts we
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* can have. Nesting 10 deep of interrupts is clearly
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* an anomaly.
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*/
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if (unlikely(++nr_loops > 10)) {
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RB_WARN_ON(cpu_buffer, 1);
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return NULL;
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}
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if (rb_per_cpu_empty(cpu_buffer))
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return NULL;
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@ -705,6 +705,7 @@ static void ftrace_trace_stack(struct trace_array *tr,
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unsigned long flags,
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int skip, int pc)
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{
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#ifdef CONFIG_STACKTRACE
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struct ring_buffer_event *event;
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struct stack_entry *entry;
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struct stack_trace trace;
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@ -730,6 +731,7 @@ static void ftrace_trace_stack(struct trace_array *tr,
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save_stack_trace(&trace);
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ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
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#endif
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}
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void __trace_stack(struct trace_array *tr,
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@ -1086,17 +1088,20 @@ static void s_stop(struct seq_file *m, void *p)
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mutex_unlock(&trace_types_lock);
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}
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#define KRETPROBE_MSG "[unknown/kretprobe'd]"
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#ifdef CONFIG_KRETPROBES
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static inline int kretprobed(unsigned long addr)
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static inline const char *kretprobed(const char *name)
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{
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return addr == (unsigned long)kretprobe_trampoline;
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static const char tramp_name[] = "kretprobe_trampoline";
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int size = sizeof(tramp_name);
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if (strncmp(tramp_name, name, size) == 0)
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return "[unknown/kretprobe'd]";
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return name;
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}
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#else
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static inline int kretprobed(unsigned long addr)
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static inline const char *kretprobed(const char *name)
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{
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return 0;
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return name;
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}
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#endif /* CONFIG_KRETPROBES */
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@ -1105,10 +1110,13 @@ seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
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{
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#ifdef CONFIG_KALLSYMS
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char str[KSYM_SYMBOL_LEN];
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const char *name;
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kallsyms_lookup(address, NULL, NULL, NULL, str);
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return trace_seq_printf(s, fmt, str);
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name = kretprobed(str);
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return trace_seq_printf(s, fmt, name);
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#endif
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return 1;
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}
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@ -1119,9 +1127,12 @@ seq_print_sym_offset(struct trace_seq *s, const char *fmt,
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{
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#ifdef CONFIG_KALLSYMS
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char str[KSYM_SYMBOL_LEN];
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const char *name;
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sprint_symbol(str, address);
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return trace_seq_printf(s, fmt, str);
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name = kretprobed(str);
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return trace_seq_printf(s, fmt, name);
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#endif
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return 1;
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}
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@ -1375,9 +1386,6 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
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seq_print_ip_sym(s, field->ip, sym_flags);
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trace_seq_puts(s, " (");
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if (kretprobed(field->parent_ip))
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trace_seq_puts(s, KRETPROBE_MSG);
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else
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seq_print_ip_sym(s, field->parent_ip, sym_flags);
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trace_seq_puts(s, ")\n");
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break;
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@ -1494,9 +1502,6 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
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ret = trace_seq_printf(s, " <-");
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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if (kretprobed(field->parent_ip))
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ret = trace_seq_puts(s, KRETPROBE_MSG);
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else
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ret = seq_print_ip_sym(s,
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field->parent_ip,
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sym_flags);
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