On Wed, 2013-04-10 at 10:30 +0900, Namhyung Kim wrote: > >From 7ba245dba217ef858b467552019acd49f7fdce7e Mon Sep 17 00:00:00 2001 > From: Namhyung Kim <[email protected]> > Date: Wed, 10 Apr 2013 09:10:44 +0900 > Subject: [PATCH] tracing: Check result of ring_buffer_read_prepare() > > The ring_buffer_read_prepare() can return NULL if memory allocation > fails. Fail out in this case instead of succedding and then having > no output. > > Suggested-by: Steven Rostedt <[email protected]> > Signed-off-by: Namhyung Kim <[email protected]> > --- > kernel/trace/trace.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 7270460cfe3c..3b3514dc8e5e 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -2826,6 +2826,8 @@ __tracing_open(struct inode *inode, struct file *file, > bool snapshot) > for_each_tracing_cpu(cpu) { > iter->buffer_iter[cpu] = > > ring_buffer_read_prepare(iter->trace_buffer->buffer, cpu); > + if (!iter->buffer_iter[cpu]) > + goto free; > } > ring_buffer_read_prepare_sync(); > for_each_tracing_cpu(cpu) { > @@ -2836,6 +2838,9 @@ __tracing_open(struct inode *inode, struct file *file, > bool snapshot) > cpu = iter->cpu_file; > iter->buffer_iter[cpu] = > ring_buffer_read_prepare(iter->trace_buffer->buffer, > cpu); > + if (!iter->buffer_iter[cpu]) > + goto free; > + > ring_buffer_read_prepare_sync(); > ring_buffer_read_start(iter->buffer_iter[cpu]); > tracing_iter_reset(iter, cpu); > @@ -2847,6 +2852,26 @@ __tracing_open(struct inode *inode, struct file *file, > bool snapshot) > > return iter; > > +free: > + if (iter->cpu_file == RING_BUFFER_ALL_CPUS) { > + for_each_tracing_cpu(cpu) { > + if (iter->buffer_iter[cpu]) > + ring_buffer_read_finish(iter->buffer_iter[cpu]); > + } > + } else { > + cpu = iter->cpu_file; > + if (iter->buffer_iter[cpu]) > + ring_buffer_read_finish(iter->buffer_iter[cpu]); > + }
As I said I would consider updating the release code, but here, it's an error path that is extremely unlikely to be hit. Please just keep the single loop, and leave out the cpu_file compare. Thanks, -- Steve > + > + if (iter->trace && iter->trace->close) > + iter->trace->close(iter); > + > + if (!iter->snapshot) > + tracing_start_tr(tr); > + > + mutex_destroy(&iter->mutex); > + free_cpumask_var(iter->started); > fail: > mutex_unlock(&trace_types_lock); > kfree(iter->trace); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
