[GIT PULL] tracing: Fixes and minor cleanups for 5.19

From: Steven Rostedt
Date: Tue Jul 12 2022 - 19:09:55 EST


Linus,

Fixes and minor clean ups for tracing:

- Fix memory leak by reverting what was thought to be a double free.
A static tool had gave a false positive that a double free was
possible in the error path, but it was actually a different location
that confused the static analyzer (and those of us that reviewed it).

- Move use of static buffers by ftrace_dump() to a location that can
be used by kgdb's ftdump(), as it needs it for the same reasons.

- Clarify in the Kconfig description that function tracing has negligible
impact on x86, but may have a bit bigger impact on other architectures.

- Remove unnecessary extra semicolon in trace event.

- Make a local variable static that is used in the fprobes sample

- Use KSYM_NAME_LEN for length of function in kprobe sample and get
rid of unneeded macro for the same purpose.


Please pull the latest trace-v5.19-rc5 tree, which can be found at:


git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v5.19-rc5

Tag SHA1: f64990a1b4d1e153bcb18e40634f008ce23cfbfd
Head SHA1: 1e1fb420fe68d9d938db360fec700dfd230cc22a


Douglas Anderson (1):
tracing: Fix sleeping while atomic in kdb ftdump

Li kunyu (1):
blk-iocost: tracing: atomic64_read(&ioc->vtime_rate) is assigned an extra semicolon

Steven Rostedt (Google) (1):
ftrace: Be more specific about arch impact when function tracer is enabled

Tiezhu Yang (1):
samples: Use KSYM_NAME_LEN for kprobes

Zheng Yejian (1):
tracing/histograms: Fix memory leak problem

sunliming (1):
fprobe/samples: Make sample_probe static

----
include/trace/events/iocost.h | 2 +-
kernel/trace/Kconfig | 3 ++-
kernel/trace/trace.c | 11 ++++++-----
kernel/trace/trace_events_hist.c | 2 ++
samples/fprobe/fprobe_example.c | 2 +-
samples/kprobes/kprobe_example.c | 5 ++---
samples/kprobes/kretprobe_example.c | 5 ++---
7 files changed, 16 insertions(+), 14 deletions(-)
---------------------------
diff --git a/include/trace/events/iocost.h b/include/trace/events/iocost.h
index e282ce02fa2d..6d1626e7a4ce 100644
--- a/include/trace/events/iocost.h
+++ b/include/trace/events/iocost.h
@@ -160,7 +160,7 @@ TRACE_EVENT(iocost_ioc_vrate_adj,

TP_fast_assign(
__assign_str(devname, ioc_name(ioc));
- __entry->old_vrate = atomic64_read(&ioc->vtime_rate);;
+ __entry->old_vrate = atomic64_read(&ioc->vtime_rate);
__entry->new_vrate = new_vrate;
__entry->busy_level = ioc->busy_level;
__entry->read_missed_ppm = missed_ppm[READ];
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index debbbb083286..ccd6a5ade3e9 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -194,7 +194,8 @@ config FUNCTION_TRACER
sequence is then dynamically patched into a tracer call when
tracing is enabled by the administrator. If it's runtime disabled
(the bootup default), then the overhead of the instructions is very
- small and not measurable even in micro-benchmarks.
+ small and not measurable even in micro-benchmarks (at least on
+ x86, but may have impact on other architectures).

config FUNCTION_GRAPH_TRACER
bool "Kernel Function Graph Tracer"
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a8cfac0611bc..b8dd54627075 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9864,6 +9864,12 @@ void trace_init_global_iter(struct trace_iterator *iter)
/* Output in nanoseconds only if we are using a clock in nanoseconds. */
if (trace_clocks[iter->tr->clock_id].in_ns)
iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
+
+ /* Can not use kmalloc for iter.temp and iter.fmt */
+ iter->temp = static_temp_buf;
+ iter->temp_size = STATIC_TEMP_BUF_SIZE;
+ iter->fmt = static_fmt_buf;
+ iter->fmt_size = STATIC_FMT_BUF_SIZE;
}

void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
@@ -9896,11 +9902,6 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)

/* Simulate the iterator */
trace_init_global_iter(&iter);
- /* Can not use kmalloc for iter.temp and iter.fmt */
- iter.temp = static_temp_buf;
- iter.temp_size = STATIC_TEMP_BUF_SIZE;
- iter.fmt = static_fmt_buf;
- iter.fmt_size = STATIC_FMT_BUF_SIZE;

for_each_tracing_cpu(cpu) {
atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled);
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 48e82e141d54..e87a46794079 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -4430,6 +4430,8 @@ static int parse_var_defs(struct hist_trigger_data *hist_data)

s = kstrdup(field_str, GFP_KERNEL);
if (!s) {
+ kfree(hist_data->attrs->var_defs.name[n_vars]);
+ hist_data->attrs->var_defs.name[n_vars] = NULL;
ret = -ENOMEM;
goto free;
}
diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index 01ee6c8c8382..58f6e8358e97 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c
@@ -20,7 +20,7 @@

#define BACKTRACE_DEPTH 16
#define MAX_SYMBOL_LEN 4096
-struct fprobe sample_probe;
+static struct fprobe sample_probe;
static unsigned long nhit;

static char symbol[MAX_SYMBOL_LEN] = "kernel_clone";
diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index f991a66b5b02..fd346f58ddba 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/samples/kprobes/kprobe_example.c
@@ -16,9 +16,8 @@
#include <linux/module.h>
#include <linux/kprobes.h>

-#define MAX_SYMBOL_LEN 64
-static char symbol[MAX_SYMBOL_LEN] = "kernel_clone";
-module_param_string(symbol, symbol, sizeof(symbol), 0644);
+static char symbol[KSYM_NAME_LEN] = "kernel_clone";
+module_param_string(symbol, symbol, KSYM_NAME_LEN, 0644);

/* For each probe you need to allocate a kprobe structure */
static struct kprobe kp = {
diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
index 228321ecb161..cbf16542d84e 100644
--- a/samples/kprobes/kretprobe_example.c
+++ b/samples/kprobes/kretprobe_example.c
@@ -23,11 +23,10 @@
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/ktime.h>
-#include <linux/limits.h>
#include <linux/sched.h>

-static char func_name[NAME_MAX] = "kernel_clone";
-module_param_string(func, func_name, NAME_MAX, S_IRUGO);
+static char func_name[KSYM_NAME_LEN] = "kernel_clone";
+module_param_string(func, func_name, KSYM_NAME_LEN, 0644);
MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
" function's execution time");