diff options
| -rw-r--r-- | kernel/trace/trace.c | 36 |
1 files changed, 33 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6c4739bee4bb..b4aa936509d2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -32,6 +32,7 @@ #include <linux/splice.h> #include <linux/kdebug.h> #include <linux/string.h> +#include <linux/mount.h> #include <linux/rwsem.h> #include <linux/slab.h> #include <linux/ctype.h> @@ -6535,6 +6536,28 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) } +static struct vfsmount *trace_automount(void *ingore) +{ + struct vfsmount *mnt; + struct file_system_type *type; + + /* + * To maintain backward compatibility for tools that mount + * debugfs to get to the tracing facility, tracefs is automatically + * mounted to the debugfs/tracing directory. + */ + type = get_fs_type("tracefs"); + if (!type) + return NULL; + mnt = vfs_kern_mount(type, 0, "tracefs", NULL); + put_filesystem(type); + if (IS_ERR(mnt)) + return NULL; + mntget(mnt); + + return mnt; +} + /** * tracing_init_dentry - initialize top level trace array * @@ -6546,14 +6569,21 @@ struct dentry *tracing_init_dentry(void) { struct trace_array *tr = &global_trace; + /* The top level trace array uses NULL as parent */ if (tr->dir) - return tr->dir; + return NULL; if (WARN_ON(!debugfs_initialized())) return ERR_PTR(-ENODEV); - tr->dir = debugfs_create_dir("tracing", NULL); - + /* + * As there may still be users that expect the tracing + * files to exist in debugfs/tracing, we must automount + * the tracefs file system there, so older tools still + * work with the newer kerenl. + */ + tr->dir = debugfs_create_automount("tracing", NULL, + trace_automount, NULL); if (!tr->dir) { pr_warn_once("Could not create debugfs directory 'tracing'\n"); return ERR_PTR(-ENOMEM); |