linux-kernel - [PATCH 2/9] relay: require non-NULL callbacks in relay

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Date:   Mon, 23 Nov 2020 19:59:22 +0200
From:   Jani Nikula <jani.nikula@...el.com>
To:     linux-kernel@...r.kernel.org
Cc:     Christoph Hellwig <hch@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        intel-gfx@...ts.freedesktop.org, jani.nikula@...el.com
Subject: [PATCH 2/9] relay: require non-NULL callbacks in relay_open()

There are no clients passing NULL callbacks, which makes sense as it
wouldn't even create a file. Require non-NULL callbacks, and throw away
the handling for NULL callbacks.

Suggested-by: Christoph Hellwig <hch@...radead.org>
Cc: Christoph Hellwig <hch@...radead.org>
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
---
 kernel/relay.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/kernel/relay.c b/kernel/relay.c
index b51343642bf4..d9b8185161a8 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -291,13 +291,6 @@ static int remove_buf_file_default_callback(struct dentry *dentry)
 	return -EINVAL;
 }
 
-/* relay channel default callbacks */
-static struct rchan_callbacks default_channel_callbacks = {
-	.subbuf_start = subbuf_start_default_callback,
-	.create_buf_file = create_buf_file_default_callback,
-	.remove_buf_file = remove_buf_file_default_callback,
-};
-
 /**
  *	wakeup_readers - wake up readers waiting on a channel
  *	@work: contains the channel buffer
@@ -472,11 +465,6 @@ static void relay_close_buf(struct rchan_buf *buf)
 static void setup_callbacks(struct rchan *chan,
 				   struct rchan_callbacks *cb)
 {
-	if (!cb) {
-		chan->cb = &default_channel_callbacks;
-		return;
-	}
-
 	if (!cb->subbuf_start)
 		cb->subbuf_start = subbuf_start_default_callback;
 	if (!cb->create_buf_file)
@@ -542,6 +530,8 @@ struct rchan *relay_open(const char *base_filename,
 		return NULL;
 	if (subbuf_size > UINT_MAX / n_subbufs)
 		return NULL;
+	if (!cb)
+		return NULL;
 
 	chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
 	if (!chan)
-- 
2.20.1