On Thu, 14 Feb 2019 16:13:28 +0200
Slavomir Kaslev <kaslevs@xxxxxxxxxx> wrote:
> Add BUFFER_FL_GUEST and BUFFER_FL_AGENT flags to differentiate when
> trace-record.c is being called to trace guest or the VM tracing agent.
>
> Also disable functions talking to the local tracefs when called in recording
> guest instances context.
>
> Signed-off-by: Slavomir Kaslev <kaslevs@xxxxxxxxxx>
> ---
> tracecmd/include/trace-local.h | 2 ++
> tracecmd/trace-record.c | 55 ++++++++++++++++++++++++++++++++--
> 2 files changed, 55 insertions(+), 2 deletions(-)
>
> diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
> index a1a06e9..f19c8bb 100644
> --- a/tracecmd/include/trace-local.h
> +++ b/tracecmd/include/trace-local.h
> @@ -149,6 +149,8 @@ char *strstrip(char *str);
> enum buffer_instance_flags {
> BUFFER_FL_KEEP = 1 << 0,
> BUFFER_FL_PROFILE = 1 << 1,
> + BUFFER_FL_GUEST = 1 << 2,
> + BUFFER_FL_AGENT = 1 << 3,
> };
>
> struct func_list {
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index 8beefab..107d3d1 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -781,6 +781,9 @@ static void __clear_trace(struct buffer_instance *instance)
> FILE *fp;
> char *path;
>
> + if (instance->flags & BUFFER_FL_GUEST)
> + return;
> +
> /* reset the trace */
> path = get_instance_file(instance, "trace");
> fp = fopen(path, "w");
> @@ -1264,6 +1267,9 @@ set_plugin_instance(struct buffer_instance *instance, const char *name)
> char *path;
> char zero = '0';
>
> + if (instance->flags & BUFFER_FL_GUEST)
> + return;
> +
> path = get_instance_file(instance, "current_tracer");
> fp = fopen(path, "w");
> if (!fp) {
> @@ -1360,6 +1366,9 @@ static void disable_func_stack_trace_instance(struct buffer_instance *instance)
> int size;
> int ret;
>
> + if (instance->flags & BUFFER_FL_GUEST)
> + return;
> +
> path = get_instance_file(instance, "current_tracer");
> ret = stat(path, &st);
> tracecmd_put_tracing_file(path);
I think we should add a:
#define is_guest(instance) ((instance)->flags & BUFFER_FL_GUEST)
Helper macro here, and all these should be turned into:
if (is_guest(instance))
return;
Less error prone, and looks cleaner.
We could add a is_agent() too in later patches.
-- Steve
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