mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-22 00:40:03 +00:00
tracing: Choose static tp_printk buffer by explicit nesting count
Currently, the trace_printk code chooses which static buffer to use based on what type of atomic context (NMI, IRQ, etc) it's in. Simplify the code and make it more robust: simply count the nesting depth and choose a buffer based on the current nesting depth. The new code will only drop an event if we nest more than 4 deep, and the old code was guaranteed to malfunction if that happened. Link: http://lkml.kernel.org/r/07ab03aecfba25fcce8f9a211b14c9c5e2865c58.1464289095.git.luto@kernel.org Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
parent
35abb67de7
commit
e2ace00117
1 changed files with 24 additions and 59 deletions
|
@ -2339,83 +2339,41 @@ static void __trace_userstack(struct trace_array *tr, unsigned long flags)
|
||||||
|
|
||||||
/* created for use with alloc_percpu */
|
/* created for use with alloc_percpu */
|
||||||
struct trace_buffer_struct {
|
struct trace_buffer_struct {
|
||||||
char buffer[TRACE_BUF_SIZE];
|
int nesting;
|
||||||
|
char buffer[4][TRACE_BUF_SIZE];
|
||||||
};
|
};
|
||||||
|
|
||||||
static struct trace_buffer_struct *trace_percpu_buffer;
|
static struct trace_buffer_struct *trace_percpu_buffer;
|
||||||
static struct trace_buffer_struct *trace_percpu_sirq_buffer;
|
|
||||||
static struct trace_buffer_struct *trace_percpu_irq_buffer;
|
|
||||||
static struct trace_buffer_struct *trace_percpu_nmi_buffer;
|
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* The buffer used is dependent on the context. There is a per cpu
|
* Thise allows for lockless recording. If we're nested too deeply, then
|
||||||
* buffer for normal context, softirq contex, hard irq context and
|
* this returns NULL.
|
||||||
* for NMI context. Thise allows for lockless recording.
|
|
||||||
*
|
|
||||||
* Note, if the buffers failed to be allocated, then this returns NULL
|
|
||||||
*/
|
*/
|
||||||
static char *get_trace_buf(void)
|
static char *get_trace_buf(void)
|
||||||
{
|
{
|
||||||
struct trace_buffer_struct *percpu_buffer;
|
struct trace_buffer_struct *buffer = this_cpu_ptr(trace_percpu_buffer);
|
||||||
|
|
||||||
/*
|
if (!buffer || buffer->nesting >= 4)
|
||||||
* If we have allocated per cpu buffers, then we do not
|
|
||||||
* need to do any locking.
|
|
||||||
*/
|
|
||||||
if (in_nmi())
|
|
||||||
percpu_buffer = trace_percpu_nmi_buffer;
|
|
||||||
else if (in_irq())
|
|
||||||
percpu_buffer = trace_percpu_irq_buffer;
|
|
||||||
else if (in_softirq())
|
|
||||||
percpu_buffer = trace_percpu_sirq_buffer;
|
|
||||||
else
|
|
||||||
percpu_buffer = trace_percpu_buffer;
|
|
||||||
|
|
||||||
if (!percpu_buffer)
|
|
||||||
return NULL;
|
return NULL;
|
||||||
|
|
||||||
return this_cpu_ptr(&percpu_buffer->buffer[0]);
|
return &buffer->buffer[buffer->nesting++][0];
|
||||||
|
}
|
||||||
|
|
||||||
|
static void put_trace_buf(void)
|
||||||
|
{
|
||||||
|
this_cpu_dec(trace_percpu_buffer->nesting);
|
||||||
}
|
}
|
||||||
|
|
||||||
static int alloc_percpu_trace_buffer(void)
|
static int alloc_percpu_trace_buffer(void)
|
||||||
{
|
{
|
||||||
struct trace_buffer_struct *buffers;
|
struct trace_buffer_struct *buffers;
|
||||||
struct trace_buffer_struct *sirq_buffers;
|
|
||||||
struct trace_buffer_struct *irq_buffers;
|
|
||||||
struct trace_buffer_struct *nmi_buffers;
|
|
||||||
|
|
||||||
buffers = alloc_percpu(struct trace_buffer_struct);
|
buffers = alloc_percpu(struct trace_buffer_struct);
|
||||||
if (!buffers)
|
if (WARN(!buffers, "Could not allocate percpu trace_printk buffer"))
|
||||||
goto err_warn;
|
return -ENOMEM;
|
||||||
|
|
||||||
sirq_buffers = alloc_percpu(struct trace_buffer_struct);
|
|
||||||
if (!sirq_buffers)
|
|
||||||
goto err_sirq;
|
|
||||||
|
|
||||||
irq_buffers = alloc_percpu(struct trace_buffer_struct);
|
|
||||||
if (!irq_buffers)
|
|
||||||
goto err_irq;
|
|
||||||
|
|
||||||
nmi_buffers = alloc_percpu(struct trace_buffer_struct);
|
|
||||||
if (!nmi_buffers)
|
|
||||||
goto err_nmi;
|
|
||||||
|
|
||||||
trace_percpu_buffer = buffers;
|
trace_percpu_buffer = buffers;
|
||||||
trace_percpu_sirq_buffer = sirq_buffers;
|
|
||||||
trace_percpu_irq_buffer = irq_buffers;
|
|
||||||
trace_percpu_nmi_buffer = nmi_buffers;
|
|
||||||
|
|
||||||
return 0;
|
return 0;
|
||||||
|
|
||||||
err_nmi:
|
|
||||||
free_percpu(irq_buffers);
|
|
||||||
err_irq:
|
|
||||||
free_percpu(sirq_buffers);
|
|
||||||
err_sirq:
|
|
||||||
free_percpu(buffers);
|
|
||||||
err_warn:
|
|
||||||
WARN(1, "Could not allocate percpu trace_printk buffer");
|
|
||||||
return -ENOMEM;
|
|
||||||
}
|
}
|
||||||
|
|
||||||
static int buffers_allocated;
|
static int buffers_allocated;
|
||||||
|
@ -2506,7 +2464,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
|
||||||
tbuffer = get_trace_buf();
|
tbuffer = get_trace_buf();
|
||||||
if (!tbuffer) {
|
if (!tbuffer) {
|
||||||
len = 0;
|
len = 0;
|
||||||
goto out;
|
goto out_nobuffer;
|
||||||
}
|
}
|
||||||
|
|
||||||
len = vbin_printf((u32 *)tbuffer, TRACE_BUF_SIZE/sizeof(int), fmt, args);
|
len = vbin_printf((u32 *)tbuffer, TRACE_BUF_SIZE/sizeof(int), fmt, args);
|
||||||
|
@ -2532,6 +2490,9 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
|
||||||
}
|
}
|
||||||
|
|
||||||
out:
|
out:
|
||||||
|
put_trace_buf();
|
||||||
|
|
||||||
|
out_nobuffer:
|
||||||
preempt_enable_notrace();
|
preempt_enable_notrace();
|
||||||
unpause_graph_tracing();
|
unpause_graph_tracing();
|
||||||
|
|
||||||
|
@ -2563,7 +2524,7 @@ __trace_array_vprintk(struct ring_buffer *buffer,
|
||||||
tbuffer = get_trace_buf();
|
tbuffer = get_trace_buf();
|
||||||
if (!tbuffer) {
|
if (!tbuffer) {
|
||||||
len = 0;
|
len = 0;
|
||||||
goto out;
|
goto out_nobuffer;
|
||||||
}
|
}
|
||||||
|
|
||||||
len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
|
len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
|
||||||
|
@ -2582,7 +2543,11 @@ __trace_array_vprintk(struct ring_buffer *buffer,
|
||||||
__buffer_unlock_commit(buffer, event);
|
__buffer_unlock_commit(buffer, event);
|
||||||
ftrace_trace_stack(&global_trace, buffer, flags, 6, pc, NULL);
|
ftrace_trace_stack(&global_trace, buffer, flags, 6, pc, NULL);
|
||||||
}
|
}
|
||||||
out:
|
|
||||||
|
out:
|
||||||
|
put_trace_buf();
|
||||||
|
|
||||||
|
out_nobuffer:
|
||||||
preempt_enable_notrace();
|
preempt_enable_notrace();
|
||||||
unpause_graph_tracing();
|
unpause_graph_tracing();
|
||||||
|
|
||||||
|
|
Loading…
Reference in a new issue