[tip: perf/core] uprobes: change uprobe_register() to use uprobe_unregister() instead of __uprobe_unregister()

[tip-bot2 for Oleg Nesterov]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     bb18c5de1c288050ef8bd4af4ca16896ad4cd3fc
Gitweb:        https://git.kernel.org/tip/bb18c5de1c288050ef8bd4af4ca16896ad4cd3fc
Author:        Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate:    Thu, 01 Aug 2024 15:27:39 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 02 Aug 2024 11:30:32 +02:00

uprobes: change uprobe_register() to use uprobe_unregister() instead of __uprobe_unregister()

If register_for_each_vma() fails uprobe_register() can safely drop
uprobe->register_rwsem and use uprobe_unregister(). There is no worry
about the races with another register/unregister, consumer_add() was
already called so this case doesn't differ from _unregister() right
after the successful _register().

Yes this means the extra up_write() + down_write(), but this is the
slow and unlikely case anyway.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240801132739.GA8809@xxxxxxxxxx
---
 kernel/events/uprobes.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index b33f139..eacf287 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1174,16 +1174,18 @@ struct uprobe *uprobe_register(struct inode *inode,
 	if (likely(uprobe_is_active(uprobe))) {
 		consumer_add(uprobe, uc);
 		ret = register_for_each_vma(uprobe, uc);
-		if (ret)
-			__uprobe_unregister(uprobe, uc);
 	}
 	up_write(&uprobe->register_rwsem);
 	put_uprobe(uprobe);
 
-	if (unlikely(ret == -EAGAIN))
-		goto retry;
+	if (ret) {
+		if (unlikely(ret == -EAGAIN))
+			goto retry;
+		uprobe_unregister(uprobe, uc);
+		return ERR_PTR(ret);
+	}
 
-	return ret ? ERR_PTR(ret) : uprobe;
+	return uprobe;
 }
 EXPORT_SYMBOL_GPL(uprobe_register);