| Message ID | 20230715141348.341887497@goodmis.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 6bba92881de9dde4c07cbb24b5691eb6eb9495f2 |
| Headers | show |
| Series | tracing: Clean up how iter is freed | expand |
On Sat, 15 Jul 2023 10:12:15 -0400 Steven Rostedt <rostedt@goodmis.org> wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > As the trace iterator is created and used by various interfaces, the clean > up of it needs to be consistent. Create a free_trace_iter_content() helper > function that frees the content of the iterator and use that to clean it > up in all places that it is used. > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Looks good to me. Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> BTW, this adds iter->fmt != static_fmt_buf check. Is it a kind of fix? Thank you, > --- > kernel/trace/trace.c | 33 ++++++++++++++++++++++----------- > 1 file changed, 22 insertions(+), 11 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 1c370ffbe062..8775930aa545 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -4815,6 +4815,25 @@ static const struct seq_operations tracer_seq_ops = { > .show = s_show, > }; > > +/* > + * Note, as iter itself can be allocated and freed in different > + * ways, this function is only used to free its content, and not > + * the iterator itself. The only requirement to all the allocations > + * is that it must zero all fields (kzalloc), as freeing works with > + * ethier allocated content or NULL. > + */ > +static void free_trace_iter_content(struct trace_iterator *iter) > +{ > + /* The fmt is either NULL, allocated or points to static_fmt_buf */ > + if (iter->fmt != static_fmt_buf) > + kfree(iter->fmt); > + > + kfree(iter->temp); > + kfree(iter->buffer_iter); > + mutex_destroy(&iter->mutex); > + free_cpumask_var(iter->started); > +} > + > static struct trace_iterator * > __tracing_open(struct inode *inode, struct file *file, bool snapshot) > { > @@ -4922,8 +4941,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot) > > fail: > mutex_unlock(&trace_types_lock); > - kfree(iter->temp); > - kfree(iter->buffer_iter); > + free_trace_iter_content(iter); > release: > seq_release_private(inode, file); > return ERR_PTR(-ENOMEM); > @@ -5002,11 +5020,7 @@ static int tracing_release(struct inode *inode, struct file *file) > > mutex_unlock(&trace_types_lock); > > - mutex_destroy(&iter->mutex); > - free_cpumask_var(iter->started); > - kfree(iter->fmt); > - kfree(iter->temp); > - kfree(iter->buffer_iter); > + free_trace_iter_content(iter); > seq_release_private(inode, file); > > return 0; > @@ -6763,10 +6777,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) > > mutex_unlock(&trace_types_lock); > > - free_cpumask_var(iter->started); > - kfree(iter->fmt); > - kfree(iter->temp); > - mutex_destroy(&iter->mutex); > + free_trace_iter_content(iter); > kfree(iter); > > trace_array_put(tr); > -- > 2.40.1
On Wed, 26 Jul 2023 22:42:13 +0900 Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > On Sat, 15 Jul 2023 10:12:15 -0400 > Steven Rostedt <rostedt@goodmis.org> wrote: > > > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > > > As the trace iterator is created and used by various interfaces, the clean > > up of it needs to be consistent. Create a free_trace_iter_content() helper > > function that frees the content of the iterator and use that to clean it > > up in all places that it is used. > > > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > > Looks good to me. > > Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > BTW, this adds iter->fmt != static_fmt_buf check. Is it a kind of fix? No, because all of the callers shouldn't actually set it to that. I added the if statement in case one of the places that do set it does call this. In other words, I added the if statement to make it more robust and prevent a bug in the future ;-) -- Steve > > Thank you, > > > --- > > kernel/trace/trace.c | 33 ++++++++++++++++++++++----------- > > 1 file changed, 22 insertions(+), 11 deletions(-) > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index 1c370ffbe062..8775930aa545 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -4815,6 +4815,25 @@ static const struct seq_operations tracer_seq_ops = { > > .show = s_show, > > }; > > > > +/* > > + * Note, as iter itself can be allocated and freed in different > > + * ways, this function is only used to free its content, and not > > + * the iterator itself. The only requirement to all the allocations > > + * is that it must zero all fields (kzalloc), as freeing works with > > + * ethier allocated content or NULL. > > + */ > > +static void free_trace_iter_content(struct trace_iterator *iter) > > +{ > > + /* The fmt is either NULL, allocated or points to static_fmt_buf */ > > + if (iter->fmt != static_fmt_buf) > > + kfree(iter->fmt); > > + > > + kfree(iter->temp); > > + kfree(iter->buffer_iter); > > + mutex_destroy(&iter->mutex); > > + free_cpumask_var(iter->started); > > +} > > + > > static struct trace_iterator * > > __tracing_open(struct inode *inode, struct file *file, bool snapshot) > > { > > @@ -4922,8 +4941,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot) > > > > fail: > > mutex_unlock(&trace_types_lock); > > - kfree(iter->temp); > > - kfree(iter->buffer_iter); > > + free_trace_iter_content(iter); > > release: > > seq_release_private(inode, file); > > return ERR_PTR(-ENOMEM); > > @@ -5002,11 +5020,7 @@ static int tracing_release(struct inode *inode, struct file *file) > > > > mutex_unlock(&trace_types_lock); > > > > - mutex_destroy(&iter->mutex); > > - free_cpumask_var(iter->started); > > - kfree(iter->fmt); > > - kfree(iter->temp); > > - kfree(iter->buffer_iter); > > + free_trace_iter_content(iter); > > seq_release_private(inode, file); > > > > return 0; > > @@ -6763,10 +6777,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) > > > > mutex_unlock(&trace_types_lock); > > > > - free_cpumask_var(iter->started); > > - kfree(iter->fmt); > > - kfree(iter->temp); > > - mutex_destroy(&iter->mutex); > > + free_trace_iter_content(iter); > > kfree(iter); > > > > trace_array_put(tr); > > -- > > 2.40.1 > >
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 1c370ffbe062..8775930aa545 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4815,6 +4815,25 @@ static const struct seq_operations tracer_seq_ops = { .show = s_show, }; +/* + * Note, as iter itself can be allocated and freed in different + * ways, this function is only used to free its content, and not + * the iterator itself. The only requirement to all the allocations + * is that it must zero all fields (kzalloc), as freeing works with + * ethier allocated content or NULL. + */ +static void free_trace_iter_content(struct trace_iterator *iter) +{ + /* The fmt is either NULL, allocated or points to static_fmt_buf */ + if (iter->fmt != static_fmt_buf) + kfree(iter->fmt); + + kfree(iter->temp); + kfree(iter->buffer_iter); + mutex_destroy(&iter->mutex); + free_cpumask_var(iter->started); +} + static struct trace_iterator * __tracing_open(struct inode *inode, struct file *file, bool snapshot) { @@ -4922,8 +4941,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot) fail: mutex_unlock(&trace_types_lock); - kfree(iter->temp); - kfree(iter->buffer_iter); + free_trace_iter_content(iter); release: seq_release_private(inode, file); return ERR_PTR(-ENOMEM); @@ -5002,11 +5020,7 @@ static int tracing_release(struct inode *inode, struct file *file) mutex_unlock(&trace_types_lock); - mutex_destroy(&iter->mutex); - free_cpumask_var(iter->started); - kfree(iter->fmt); - kfree(iter->temp); - kfree(iter->buffer_iter); + free_trace_iter_content(iter); seq_release_private(inode, file); return 0; @@ -6763,10 +6777,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) mutex_unlock(&trace_types_lock); - free_cpumask_var(iter->started); - kfree(iter->fmt); - kfree(iter->temp); - mutex_destroy(&iter->mutex); + free_trace_iter_content(iter); kfree(iter); trace_array_put(tr);