uprobes/tracing: Introduce is_trace_uprobe_enabled()

probe_event_enable/disable() check tu->consumer != NULL to avoid the
wrong uprobe_register/unregister().

We are going to kill this pointer and "struct uprobe_trace_consumer",
so we add the new helper, is_trace_uprobe_enabled(), which can rely
on TP_FLAG_TRACE/TP_FLAG_PROFILE instead.

Note: the current logic doesn't look optimal, it is not clear why
TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive, we will probably
change this later.

Also kill the unused TP_FLAG_UPROBE.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

2 files changed, 7 insertions, 3 deletions

diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 933708677814..5c7e09d10d74 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -66,7 +66,6 @@
 #define TP_FLAG_TRACE           1
 #define TP_FLAG_PROFILE         2
 #define TP_FLAG_REGISTERED      4
-#define TP_FLAG_UPROBE          8
 
 
 /* data_rloc: data relative location, compatible with u32 */
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index f7838cfd61b9..d6c6e2a345a7 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -539,12 +539,17 @@ partial:
         return TRACE_TYPE_PARTIAL_LINE;
 }
 
+static inline bool is_trace_uprobe_enabled(struct trace_uprobe *tu)
+{
+        return tu->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE);
+}
+
 static int probe_event_enable(struct trace_uprobe *tu, int flag)
 {
         struct uprobe_trace_consumer *utc;
         int ret = 0;
 
-        if (tu->consumer)
+        if (is_trace_uprobe_enabled(tu))
                 return -EINTR;
 
         utc = kzalloc(sizeof(struct uprobe_trace_consumer), GFP_KERNEL);
@@ -568,7 +573,7 @@ static int probe_event_enable(struct trace_uprobe *tu, int flag)
 
 static void probe_event_disable(struct trace_uprobe *tu, int flag)
 {
-        if (!tu->consumer)
+        if (!is_trace_uprobe_enabled(tu))
                 return;
 
         uprobe_unregister(tu->inode, tu->offset, &tu->consumer->cons);