Commit 55034cd6 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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tracing: Add alloc_snapshot kernel command line parameter



If debugging the kernel, and the developer wants to use
tracing_snapshot() in places where tracing_snapshot_alloc() may
be difficult (or more likely, the developer is lazy and doesn't
want to bother with tracing_snapshot_alloc() at all), then adding

  alloc_snapshot

to the kernel command line parameter will tell ftrace to allocate
the snapshot buffer (if configured) when it allocates the main
tracing buffer.

I also noticed that ring_buffer_expanded and tracing_selftest_disabled
had inconsistent use of boolean "true" and "false" with "0" and "1".
I cleaned that up too.
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent f4e781c0
......@@ -320,6 +320,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
on: enable for both 32- and 64-bit processes
off: disable for both 32- and 64-bit processes
alloc_snapshot [FTRACE]
Allocate the ftrace snapshot buffer on boot up when the
main buffer is allocated. This is handy if debugging
and you need to use tracing_snapshot() on boot up, and
do not want to use tracing_snapshot_alloc() as it needs
to be done where GFP_KERNEL allocations are allowed.
amd_iommu= [HW,X86-64]
Pass parameters to the AMD IOMMU driver in the system.
Possible values are:
......
......@@ -47,7 +47,7 @@
* On boot up, the ring buffer is set to the minimum size, so that
* we do not waste memory on systems that are not using tracing.
*/
int ring_buffer_expanded;
bool ring_buffer_expanded;
/*
* We need to change this state when a selftest is running.
......@@ -121,12 +121,14 @@ static int tracing_set_tracer(const char *buf);
static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
static char *default_bootup_tracer;
static bool allocate_snapshot;
static int __init set_cmdline_ftrace(char *str)
{
strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
default_bootup_tracer = bootup_tracer_buf;
/* We are using ftrace early, expand it */
ring_buffer_expanded = 1;
ring_buffer_expanded = true;
return 1;
}
__setup("ftrace=", set_cmdline_ftrace);
......@@ -147,6 +149,15 @@ static int __init set_ftrace_dump_on_oops(char *str)
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
static int __init alloc_snapshot(char *str)
{
allocate_snapshot = true;
/* We also need the main ring buffer expanded */
ring_buffer_expanded = true;
return 1;
}
__setup("alloc_snapshot", alloc_snapshot);
static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
static char *trace_boot_options __initdata;
......@@ -951,7 +962,7 @@ int register_tracer(struct tracer *type)
tracing_set_tracer(type->name);
default_bootup_tracer = NULL;
/* disable other selftests, since this will break it. */
tracing_selftest_disabled = 1;
tracing_selftest_disabled = true;
#ifdef CONFIG_FTRACE_STARTUP_TEST
printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
type->name);
......@@ -3318,7 +3329,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
* we use the size that was given, and we can forget about
* expanding it later.
*/
ring_buffer_expanded = 1;
ring_buffer_expanded = true;
/* May be called before buffers are initialized */
if (!tr->trace_buffer.buffer)
......@@ -5396,53 +5407,57 @@ static void init_trace_buffers(struct trace_array *tr, struct trace_buffer *buf)
}
}
static int allocate_trace_buffers(struct trace_array *tr, int size)
static int
allocate_trace_buffer(struct trace_array *tr, struct trace_buffer *buf, int size)
{
enum ring_buffer_flags rb_flags;
rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
tr->trace_buffer.buffer = ring_buffer_alloc(size, rb_flags);
if (!tr->trace_buffer.buffer)
goto out_free;
buf->buffer = ring_buffer_alloc(size, rb_flags);
if (!buf->buffer)
return -ENOMEM;
tr->trace_buffer.data = alloc_percpu(struct trace_array_cpu);
if (!tr->trace_buffer.data)
goto out_free;
buf->data = alloc_percpu(struct trace_array_cpu);
if (!buf->data) {
ring_buffer_free(buf->buffer);
return -ENOMEM;
}
init_trace_buffers(tr, &tr->trace_buffer);
init_trace_buffers(tr, buf);
/* Allocate the first page for all buffers */
set_buffer_entries(&tr->trace_buffer,
ring_buffer_size(tr->trace_buffer.buffer, 0));
#ifdef CONFIG_TRACER_MAX_TRACE
tr->max_buffer.buffer = ring_buffer_alloc(1, rb_flags);
if (!tr->max_buffer.buffer)
goto out_free;
tr->max_buffer.data = alloc_percpu(struct trace_array_cpu);
if (!tr->max_buffer.data)
goto out_free;
return 0;
}
init_trace_buffers(tr, &tr->max_buffer);
static int allocate_trace_buffers(struct trace_array *tr, int size)
{
int ret;
set_buffer_entries(&tr->max_buffer, 1);
#endif
return 0;
ret = allocate_trace_buffer(tr, &tr->trace_buffer, size);
if (ret)
return ret;
out_free:
if (tr->trace_buffer.buffer)
#ifdef CONFIG_TRACER_MAX_TRACE
ret = allocate_trace_buffer(tr, &tr->max_buffer,
allocate_snapshot ? size : 1);
if (WARN_ON(ret)) {
ring_buffer_free(tr->trace_buffer.buffer);
free_percpu(tr->trace_buffer.data);
free_percpu(tr->trace_buffer.data);
return -ENOMEM;
}
tr->allocated_snapshot = allocate_snapshot;
#ifdef CONFIG_TRACER_MAX_TRACE
if (tr->max_buffer.buffer)
ring_buffer_free(tr->max_buffer.buffer);
free_percpu(tr->max_buffer.data);
/*
* Only the top level trace array gets its snapshot allocated
* from the kernel command line.
*/
allocate_snapshot = false;
#endif
return -ENOMEM;
return 0;
}
static int new_instance_create(const char *name)
......
......@@ -660,7 +660,7 @@ extern int DYN_FTRACE_TEST_NAME(void);
#define DYN_FTRACE_TEST_NAME2 trace_selftest_dynamic_test_func2
extern int DYN_FTRACE_TEST_NAME2(void);
extern int ring_buffer_expanded;
extern bool ring_buffer_expanded;
extern bool tracing_selftest_disabled;
DECLARE_PER_CPU(int, ftrace_cpu_disabled);
......
......@@ -1844,8 +1844,8 @@ static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata;
static __init int setup_trace_event(char *str)
{
strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
ring_buffer_expanded = 1;
tracing_selftest_disabled = 1;
ring_buffer_expanded = true;
tracing_selftest_disabled = true;
return 1;
}
......
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