[PATCH 1/3] ksym_tracer: Fix breakpoint removal after modification

[Frederic Weisbecker <fweisbec@gmail.com>]

The error path of a breakpoint modification is broken in
the ksym tracer. A modified breakpoint hlist node is immediately
released after its removal. Also we leak a breakpoint in this
case.

Fix the path.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
---
 kernel/trace/trace_ksym.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 11935b5..9f040e4 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -339,14 +339,20 @@ static ssize_t ksym_trace_filter_write(struct file *file,
 					ksym_hbp_handler, true);
 			if (IS_ERR(entry->ksym_hbp))
 				entry->ksym_hbp = NULL;
-			if (!entry->ksym_hbp)
+
+			/* modified without problem */
+			if (entry->ksym_hbp) {
+				ret = 0;
 				goto out;
+			}
+		} else {
+			ret = 0;
 		}
+		/* Error or "symbol:---" case: drop it */
 		ksym_filter_entry_count--;
 		hlist_del_rcu(&(entry->ksym_hlist));
 		synchronize_rcu();
 		kfree(entry);
-		ret = 0;
 		goto out;
 	} else {
 		/* Check for malformed request: (4) */
-- 
1.6.2.3