Thread (8 messages) 8 messages, 3 authors, 2025-09-23

Re: [PATCH] rv: Fix wrong type cast in enabled_monitors_next()

From: Gabriele Monaco <gmonaco@redhat.com>
Date: 2025-08-06 12:45:28
Also in: lkml


On Wed, 2025-08-06 at 14:09 +0200, Nam Cao wrote:
Argument 'p' of enabled_monitors_next() is not a pointer to struct
rv_monitor, it is actually a pointer to the list_head inside struct
rv_monitor. Therefore it is wrong to cast 'p' to struct rv_monitor *.

This wrong type cast has been there since the beginning. But it still
worked because the list_head was the first field in struct
rv_monitor_def.
This is no longer true since commit 24cbfe18d55a ("rv: Merge struct
rv_monitor_def into struct rv_monitor") moved the list_head, and this
wrong type cast became a functional problem.

Properly use container_of() instead.
Good catch, thanks!

Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
quoted hunk ↗ jump to hunk
Fixes: 24cbfe18d55a ("rv: Merge struct rv_monitor_def into struct
rv_monitor")
Signed-off-by: Nam Cao <redacted>
---
 kernel/trace/rv/rv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c
index bd7d56dbf6c2..6ce3495164d8 100644
--- a/kernel/trace/rv/rv.c
+++ b/kernel/trace/rv/rv.c
@@ -495,7 +495,7 @@ static void *available_monitors_next(struct
seq_file *m, void *p, loff_t *pos)
  */
 static void *enabled_monitors_next(struct seq_file *m, void *p,
loff_t *pos)
 {
-	struct rv_monitor *mon = p;
+	struct rv_monitor *mon = container_of(p, struct rv_monitor,
list);
 
 	(*pos)++;
 
  
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