kmemtrace: allow kmemtrace to be enabled after boot

The kmemtrace_init() function returns early if kmemtrace is disabled at boot
causing kmemtrace_setup_late() to also bail out on NULL channel. This has the
unfortunate side effect that none of the debugfs files needed to enable
kmemtrace after boot are created.

Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

1 files changed, 13 insertions, 13 deletions

diff --git a/mm/kmemtrace.c b/mm/kmemtrace.c
index 83ad1cc71a92..f7a49c077df2 100644
--- a/mm/kmemtrace.c
+++ b/mm/kmemtrace.c
@@ -307,29 +307,29 @@ early_param("kmemtrace.subbufs", kmemtrace_set_subbufs);
 
 void kmemtrace_init(void)
 {
-        if (!kmemtrace_enabled)
-                return;
-
         if (!kmemtrace_n_subbufs)
                 kmemtrace_n_subbufs = KMEMTRACE_DEF_N_SUBBUFS;
 
         kmemtrace_chan = relay_open(NULL, NULL, KMEMTRACE_SUBBUF_SIZE,
                                     kmemtrace_n_subbufs, &relay_callbacks,
                                     NULL);
-        if (unlikely(!kmemtrace_chan)) {
+        if (!kmemtrace_chan) {
                 printk(KERN_ERR "kmemtrace: could not open relay channel.\n");
                 return;
         }
 
-        if (unlikely(kmemtrace_start_probes()))
-                goto probe_fail;
-
-        printk(KERN_INFO "kmemtrace: early init successful.\n");
-
-        return;
+        if (!kmemtrace_enabled) {
+                printk(KERN_INFO "kmemtrace: disabled. Pass "
+                        "kemtrace.enable=yes as kernel parameter for "
+                        "boot-time tracing.");
+                return;
+        }
+        if (kmemtrace_start_probes()) {
+                printk(KERN_ERR "kmemtrace: could not register marker probes!\n");
+                kmemtrace_cleanup();
+                return;
+        }
 
-probe_fail:
-        printk(KERN_ERR "kmemtrace: could not register marker probes!\n");
-        kmemtrace_cleanup();
+        printk(KERN_INFO "kmemtrace: enabled.\n");
 }