diff options
| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-06-29 23:45:56 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-21 13:05:27 +0200 |
| commit | 43e172e31badc6155314b14ce73d41571aecff2c (patch) | |
| tree | b9c3618ca405fa42c64f8547f8241ac47eeac3d2 /kernel | |
| parent | 9aab8b2b0f8f77c0a14548c90ec88ede1d5fe8d7 (diff) | |
tracing: Move pipe reference to trace array instead of current_tracer
commit 7ef282e05132d56b6f6b71e3873f317664bea78b upstream.
If a process has the trace_pipe open on a trace_array, the current tracer
for that trace array should not be changed. This was original enforced by a
global lock, but when instances were introduced, it was moved to the
current_trace. But this structure is shared by all instances, and a
trace_pipe is for a single instance. There's no reason that a process that
has trace_pipe open on one instance should prevent another instance from
changing its current tracer. Move the reference counter to the trace_array
instead.
This is marked as "Fixes" but is more of a clean up than a true fix.
Backport if you want, but its not critical.
Fixes: cf6ab6d9143b1 ("tracing: Add ref count to tracer for when they are being read by pipe")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[Resolved conflict in __remove_instance()]
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace.c | 12 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 2 |
2 files changed, 7 insertions, 7 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 721947b9962d..f9c2bdbbd893 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5686,7 +5686,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf) } /* If trace pipe files are being read, we can't change the tracer */ - if (tr->current_trace->ref) { + if (tr->trace_ref) { ret = -EBUSY; goto out; } @@ -5902,7 +5902,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp) nonseekable_open(inode, filp); - tr->current_trace->ref++; + tr->trace_ref++; out: mutex_unlock(&trace_types_lock); return ret; @@ -5921,7 +5921,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) mutex_lock(&trace_types_lock); - tr->current_trace->ref--; + tr->trace_ref--; if (iter->trace->pipe_close) iter->trace->pipe_close(iter); @@ -7230,7 +7230,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) filp->private_data = info; - tr->current_trace->ref++; + tr->trace_ref++; mutex_unlock(&trace_types_lock); @@ -7331,7 +7331,7 @@ static int tracing_buffers_release(struct inode *inode, struct file *file) mutex_lock(&trace_types_lock); - iter->tr->current_trace->ref--; + iter->tr->trace_ref--; __trace_array_put(iter->tr); @@ -8470,7 +8470,7 @@ static int __remove_instance(struct trace_array *tr) { int i; - if (tr->ref || (tr->current_trace && tr->current_trace->ref)) + if (tr->ref || (tr->current_trace && tr->trace_ref)) return -EBUSY; list_del(&tr->list); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index a3c29d5fcc61..4055158c1dd2 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -309,6 +309,7 @@ struct trace_array { struct trace_event_file *trace_marker_file; cpumask_var_t tracing_cpumask; /* only trace on set CPUs */ int ref; + int trace_ref; #ifdef CONFIG_FUNCTION_TRACER struct ftrace_ops *ops; struct trace_pid_list __rcu *function_pids; @@ -498,7 +499,6 @@ struct tracer { struct tracer *next; struct tracer_flags *flags; int enabled; - int ref; bool print_max; bool allow_instances; #ifdef CONFIG_TRACER_MAX_TRACE |