ksym_tracer: Fix breakpoint removal after modification

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>
LKML-Reference: <1259210142-5714-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 2 deletions

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 11935b53a6cb..9f040e42f516 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) */