[for-next][PATCH 2/4] uprobes: Change unregister/apply to WARN() if uprobe/consumer is gone

[Steven Rostedt]

From: Oleg Nesterov <oleg@xxxxxxxxxx>

Add WARN_ON's into uprobe_unregister() and uprobe_apply() to ensure
that nobody tries to play with the dead uprobe/consumer. This helps
to catch the bugs like the one fixed by the previous patch.

In the longer term we should fix this poorly designed interface.
uprobe_register() should return "struct uprobe *" which should be
passed to apply/unregister. Plus other semantic changes, see the
changelog in commit 41ccba029e94.

Link: http://lkml.kernel.org/p/20140627170140.GA18322@xxxxxxxxxx

Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/events/uprobes.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index c445e392e93f..6f3254e8c137 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -846,7 +846,7 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u
 {
 	int err;
 
-	if (!consumer_del(uprobe, uc))	/* WARN? */
+	if (WARN_ON(!consumer_del(uprobe, uc)))
 		return;
 
 	err = register_for_each_vma(uprobe, NULL);
@@ -927,7 +927,7 @@ int uprobe_apply(struct inode *inode, loff_t offset,
 	int ret = -ENOENT;
 
 	uprobe = find_uprobe(inode, offset);
-	if (!uprobe)
+	if (WARN_ON(!uprobe))
 		return ret;
 
 	down_write(&uprobe->register_rwsem);
@@ -952,7 +952,7 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume
 	struct uprobe *uprobe;
 
 	uprobe = find_uprobe(inode, offset);
-	if (!uprobe)
+	if (WARN_ON(!uprobe))
 		return;
 
 	down_write(&uprobe->register_rwsem);
-- 
2.0.0


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