Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/2] tracing: Miscellaneous fixes for trace_array ref counting | From | Steven Rostedt <> | Date | Thu, 18 Jul 2013 12:31:27 -0400 |
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On Wed, 2013-07-10 at 17:34 -0700, Alexander Z Lam wrote: > Some error paths did not handle ref counting properly, and some trace files need > ref counting. > > Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> > Cc: David Sharp <dhsharp@google.com> > Cc: Alexander Z Lam <lambchop468@gmail.com> > Signed-off-by: Alexander Z Lam <azl@google.com> > --- > kernel/trace/trace.c | 34 +++++++++++++++++++++++----------- > kernel/trace/trace_events.c | 21 +++++++++++++++++++-- > 2 files changed, 42 insertions(+), 13 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 0cd500b..ca2743b 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -3008,7 +3008,6 @@ static int tracing_release(struct inode *inode, struct file *file) > > iter = m->private; > tr = iter->tr; > - trace_array_put(tr); > > mutex_lock(&trace_types_lock); > > @@ -3023,6 +3022,9 @@ static int tracing_release(struct inode *inode, struct file *file) > if (!iter->snapshot) > /* reenable tracing if it was previously enabled */ > tracing_start_tr(tr); > + > + __trace_array_put(tr); > + > mutex_unlock(&trace_types_lock); > > mutex_destroy(&iter->mutex); > @@ -3447,6 +3449,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, > static int tracing_trace_options_open(struct inode *inode, struct file *file) > { > struct trace_array *tr = inode->i_private; > + int ret; > > if (tracing_disabled) > return -ENODEV; > @@ -3454,7 +3457,11 @@ static int tracing_trace_options_open(struct inode *inode, struct file *file) > if (trace_array_get(tr) < 0) > return -ENODEV; > > - return single_open(file, tracing_trace_options_show, inode->i_private); > + ret = single_open(file, tracing_trace_options_show, inode->i_private); > + if (ret < 0) > + trace_array_put(tr); > + > + return ret; > } > > static const struct file_operations tracing_iter_fops = { > @@ -3958,7 +3965,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp) > iter = kzalloc(sizeof(*iter), GFP_KERNEL); > if (!iter) { > ret = -ENOMEM; > - goto out; > + goto fail_iter;
It would be cleaner to not add the extra label, and just do a trace_array_put() in the if statement.
> } > > /* > @@ -3968,13 +3975,13 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp) > iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL); > if (!iter->trace) { > ret = -ENOMEM; > - goto fail; > + goto fail_trace; > } > *iter->trace = *tr->current_trace; > > if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) { > ret = -ENOMEM; > - goto fail; > + goto fail_trace; > } > > /* trace pipe does not show start of buffer */ > @@ -4001,9 +4008,10 @@ out: > mutex_unlock(&trace_types_lock); > return ret; > > -fail: > +fail_trace: > kfree(iter->trace); > kfree(iter); > +fail_iter: > __trace_array_put(tr); > mutex_unlock(&trace_types_lock); > return ret; > @@ -4705,12 +4713,15 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file) > } else { > /* Writes still need the seq_file to hold the private data */ > m = kzalloc(sizeof(*m), GFP_KERNEL); > - if (!m) > - return -ENOMEM; > + if (!m) { > + ret = -ENOMEM; > + goto out; > + }
Instead of adding the complex if statement, do this:
int ret = -ENOMEM;
[..]
if (!m) goto out;
And then after the if statements:
ret = 0;
> iter = kzalloc(sizeof(*iter), GFP_KERNEL); > if (!iter) { > kfree(m); > - return -ENOMEM; > + ret = -ENOMEM; > + goto out; > } > iter->tr = tr; > iter->trace_buffer = &tc->tr->max_buffer; > @@ -4718,7 +4729,7 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file) > m->private = iter; > file->private_data = m; > } > - > +out: > if (ret < 0) > trace_array_put(tr); >
The rest looks good. Although, we may be rewriting all this code because there still exists some races. See the email threads between Oleg and Masami.
-- Steve
> @@ -5328,9 +5339,10 @@ tracing_stats_read(struct file *filp, char __user *ubuf, > } > > static const struct file_operations tracing_stats_fops = { > - .open = tracing_open_generic, > + .open = tracing_open_generic_tc, > .read = tracing_stats_read, > .llseek = generic_file_llseek, > + .release = tracing_release_generic_tc, > }; > > #ifdef CONFIG_DYNAMIC_FTRACE > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index 7d85429..7a75cb2 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -1218,6 +1218,7 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) > > static int ftrace_event_avail_open(struct inode *inode, struct file *file); > static int ftrace_event_set_open(struct inode *inode, struct file *file); > +static int ftrace_event_release(struct inode *inode, struct file *file); > > static const struct seq_operations show_event_seq_ops = { > .start = t_start, > @@ -1245,7 +1246,7 @@ static const struct file_operations ftrace_set_event_fops = { > .read = seq_read, > .write = ftrace_event_write, > .llseek = seq_lseek, > - .release = seq_release, > + .release = ftrace_event_release, > }; > > static const struct file_operations ftrace_enable_fops = { > @@ -1323,6 +1324,15 @@ ftrace_event_open(struct inode *inode, struct file *file, > return ret; > } > > +static int ftrace_event_release(struct inode *inode, struct file *file) > +{ > + struct trace_array *tr = inode->i_private; > + > + trace_array_put(tr); > + > + return seq_release(inode, file); > +} > + > static int > ftrace_event_avail_open(struct inode *inode, struct file *file) > { > @@ -1336,12 +1346,19 @@ ftrace_event_set_open(struct inode *inode, struct file *file) > { > const struct seq_operations *seq_ops = &show_set_event_seq_ops; > struct trace_array *tr = inode->i_private; > + int ret; > + > + if (trace_array_get(tr) < 0) > + return -ENODEV; > > if ((file->f_mode & FMODE_WRITE) && > (file->f_flags & O_TRUNC)) > ftrace_clear_events(tr); > > - return ftrace_event_open(inode, file, seq_ops); > + ret = ftrace_event_open(inode, file, seq_ops); > + if (ret < 0) > + trace_array_put(tr); > + return ret; > } > > static struct event_subsystem *
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