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tracing/kprobes: Use rcu_dereference_raw for tp->files

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Use rcu_dereference_raw() for accessing tp->files. Because the
write-side uses rcu_assign_pointer() for memory barrier,
the read-side also has to use rcu_dereference_raw() with
read memory barrier.

Link: http://lkml.kernel.org/r/20130513115834.6545.17022.stgit@mhiramat-M0-7522

Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tom Zanussi <tom.zanussi@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2013-05-13 20:58:34 +09:00 committed by Steven Rostedt
parent 60705c8946
commit c02c7e65d9
1 changed files with 37 additions and 10 deletions
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47
kernel/trace/trace_kprobe.c
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@ -185,9 +185,14 @@ static struct trace_probe *find_trace_probe(const char *event,
static int trace_probe_nr_files(struct trace_probe *tp)
{
struct ftrace_event_file **file = tp->files;
struct ftrace_event_file **file;
int ret = 0;
/*
* Since all tp->files updater is protected by probe_enable_lock,
* we don't need to lock an rcu_read_lock.
*/
file = rcu_dereference_raw(tp->files);
if (file)
while (*(file++))
ret++;
@ -209,9 +214,10 @@ enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
mutex_lock(&probe_enable_lock);
if (file) {
struct ftrace_event_file **new, **old = tp->files;
struct ftrace_event_file **new, **old;
int n = trace_probe_nr_files(tp);
old = rcu_dereference_raw(tp->files);
/* 1 is for new one and 1 is for stopper */
new = kzalloc((n + 2) * sizeof(struct ftrace_event_file *),
GFP_KERNEL);
@ -251,11 +257,17 @@ enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
static int
trace_probe_file_index(struct trace_probe *tp, struct ftrace_event_file *file)
{
struct ftrace_event_file **files;
int i;
if (tp->files) {
for (i = 0; tp->files[i]; i++)
if (tp->files[i] == file)
/*
* Since all tp->files updater is protected by probe_enable_lock,
* we don't need to lock an rcu_read_lock.
*/
files = rcu_dereference_raw(tp->files);
if (files) {
for (i = 0; files[i]; i++)
if (files[i] == file)
return i;
}
@ -274,10 +286,11 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
mutex_lock(&probe_enable_lock);
if (file) {
struct ftrace_event_file **new, **old = tp->files;
struct ftrace_event_file **new, **old;
int n = trace_probe_nr_files(tp);
int i, j;
old = rcu_dereference_raw(tp->files);
if (n == 0 || trace_probe_file_index(tp, file) < 0) {
ret = -EINVAL;
goto out_unlock;
@ -872,9 +885,16 @@ __kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
static __kprobes void
kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
{
struct ftrace_event_file **file = tp->files;
/*
* Note: preempt is already disabled around the kprobe handler.
* However, we still need an smp_read_barrier_depends() corresponding
* to smp_wmb() in rcu_assign_pointer() to access the pointer.
*/
struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
if (unlikely(!file))
return;
/* Note: preempt is already disabled around the kprobe handler */
while (*file) {
__kprobe_trace_func(tp, regs, *file);
file++;
@ -925,9 +945,16 @@ static __kprobes void
kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
struct pt_regs *regs)
{
struct ftrace_event_file **file = tp->files;
/*
* Note: preempt is already disabled around the kprobe handler.
* However, we still need an smp_read_barrier_depends() corresponding
* to smp_wmb() in rcu_assign_pointer() to access the pointer.
*/
struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
if (unlikely(!file))
return;
/* Note: preempt is already disabled around the kprobe handler */
while (*file) {
__kretprobe_trace_func(tp, ri, regs, *file);
file++;