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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'
This commit is contained in:
Linus Torvalds 2008-11-03 10:21:40 -08:00
parent da4a22cba7 818e3dd30a
commit 457d2ee225
3 changed files with 80 additions and 19 deletions
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2
kernel/trace/Kconfig
View File

@ -25,7 +25,7 @@ config TRACING
bool
select DEBUG_FS
select RING_BUFFER
select STACKTRACE
select STACKTRACE if STACKTRACE_SUPPORT
select TRACEPOINTS
select NOP_TRACER

56
kernel/trace/ring_buffer.c
View File

@ -1022,8 +1022,23 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
struct ring_buffer_event *event;
u64 ts, delta;
int commit = 0;
int nr_loops = 0;
again:
/*
* We allow for interrupts to reenter here and do a trace.
* If one does, it will cause this original code to loop
* back here. Even with heavy interrupts happening, this
* should only happen a few times in a row. If this happens
* 1000 times in a row, there must be either an interrupt
* storm or we have something buggy.
* Bail!
*/
if (unlikely(++nr_loops > 1000)) {
RB_WARN_ON(cpu_buffer, 1);
return NULL;
}
ts = ring_buffer_time_stamp(cpu_buffer->cpu);
/*
@ -1532,10 +1547,23 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
{
struct buffer_page *reader = NULL;
unsigned long flags;
int nr_loops = 0;
spin_lock_irqsave(&cpu_buffer->lock, flags);
again:
/*
* This should normally only loop twice. But because the
* start of the reader inserts an empty page, it causes
* 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);
reader = NULL;
goto out;
}
reader = cpu_buffer->reader_page;
/* If there's more to read, return this page */
@ -1665,6 +1693,7 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event;
struct buffer_page *reader;
int nr_loops = 0;
if (!cpu_isset(cpu, buffer->cpumask))
return NULL;
@ -1672,6 +1701,19 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
cpu_buffer = buffer->buffers[cpu];
again:
/*
* We repeat when a timestamp is encountered. It is possible
* to get multiple timestamps from an interrupt entering just
* as one timestamp is about to be written. The max times
* that this can happen is the number of nested interrupts we
* can have. Nesting 10 deep of interrupts is clearly
* an anomaly.
*/
if (unlikely(++nr_loops > 10)) {
RB_WARN_ON(cpu_buffer, 1);
return NULL;
}
reader = rb_get_reader_page(cpu_buffer);
if (!reader)
return NULL;
@ -1722,6 +1764,7 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
struct ring_buffer *buffer;
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event;
int nr_loops = 0;
if (ring_buffer_iter_empty(iter))
return NULL;
@ -1730,6 +1773,19 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
buffer = cpu_buffer->buffer;
again:
/*
* We repeat when a timestamp is encountered. It is possible
* to get multiple timestamps from an interrupt entering just
* as one timestamp is about to be written. The max times
* that this can happen is the number of nested interrupts we
* can have. Nesting 10 deep of interrupts is clearly
* an anomaly.
*/
if (unlikely(++nr_loops > 10)) {
RB_WARN_ON(cpu_buffer, 1);
return NULL;
}
if (rb_per_cpu_empty(cpu_buffer))
return NULL;

41
kernel/trace/trace.c
View File

@ -705,6 +705,7 @@ static void ftrace_trace_stack(struct trace_array *tr,
unsigned long flags,
int skip, int pc)
{
#ifdef CONFIG_STACKTRACE
struct ring_buffer_event *event;
struct stack_entry *entry;
struct stack_trace trace;
@ -730,6 +731,7 @@ static void ftrace_trace_stack(struct trace_array *tr,
save_stack_trace(&trace);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
#endif
}
void __trace_stack(struct trace_array *tr,
@ -1086,17 +1088,20 @@ static void s_stop(struct seq_file *m, void *p)
mutex_unlock(&trace_types_lock);
}
#define KRETPROBE_MSG "[unknown/kretprobe'd]"
#ifdef CONFIG_KRETPROBES
static inline int kretprobed(unsigned long addr)
static inline const char *kretprobed(const char *name)
{
return addr == (unsigned long)kretprobe_trampoline;
static const char tramp_name[] = "kretprobe_trampoline";
int size = sizeof(tramp_name);
if (strncmp(tramp_name, name, size) == 0)
return "[unknown/kretprobe'd]";
return name;
}
#else
static inline int kretprobed(unsigned long addr)
static inline const char *kretprobed(const char *name)
{
return 0;
return name;
}
#endif /* CONFIG_KRETPROBES */
@ -1105,10 +1110,13 @@ seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
{
#ifdef CONFIG_KALLSYMS
char str[KSYM_SYMBOL_LEN];
const char *name;
kallsyms_lookup(address, NULL, NULL, NULL, str);
return trace_seq_printf(s, fmt, str);
name = kretprobed(str);
return trace_seq_printf(s, fmt, name);
#endif
return 1;
}
@ -1119,9 +1127,12 @@ seq_print_sym_offset(struct trace_seq *s, const char *fmt,
{
#ifdef CONFIG_KALLSYMS
char str[KSYM_SYMBOL_LEN];
const char *name;
sprint_symbol(str, address);
return trace_seq_printf(s, fmt, str);
name = kretprobed(str);
return trace_seq_printf(s, fmt, name);
#endif
return 1;
}
@ -1375,10 +1386,7 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
seq_print_ip_sym(s, field->ip, sym_flags);
trace_seq_puts(s, " (");
if (kretprobed(field->parent_ip))
trace_seq_puts(s, KRETPROBE_MSG);
else
seq_print_ip_sym(s, field->parent_ip, sym_flags);
seq_print_ip_sym(s, field->parent_ip, sym_flags);
trace_seq_puts(s, ")\n");
break;
}
@ -1494,12 +1502,9 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
ret = trace_seq_printf(s, " <-");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
if (kretprobed(field->parent_ip))
ret = trace_seq_puts(s, KRETPROBE_MSG);
else
ret = seq_print_ip_sym(s,
field->parent_ip,
sym_flags);
ret = seq_print_ip_sym(s,
field->parent_ip,
sym_flags);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}