From 371e03880d9d34534d3eafd2a7581042be598e39 Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Tue, 15 Dec 2020 20:45:53 -0800 Subject: [PATCH] relay: make create_buf_file and remove_buf_file callbacks mandatory All clients provide create_buf_file and remove_buf_file callbacks, and they're required for relay to make sense. There is no point in them being optional. Also document whether each callback is mandatory/optional. Link: https://lkml.kernel.org/r/88003c1527386b93036e286e7917f1e33aec84ac.1606153547.git.jani.nikula@intel.com Signed-off-by: Jani Nikula Suggested-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Cc: Jens Axboe Cc: Kalle Valo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/relay.h | 6 ++++++ kernel/relay.c | 26 +------------------------- 2 files changed, 7 insertions(+), 25 deletions(-) diff --git a/include/linux/relay.h b/include/linux/relay.h index b3c4f49f6951..99d024475ba5 100644 --- a/include/linux/relay.h +++ b/include/linux/relay.h @@ -89,6 +89,8 @@ struct rchan_callbacks * The client should return 1 to continue logging, 0 to stop * logging. * + * This callback is optional. + * * NOTE: subbuf_start will also be invoked when the buffer is * created, so that the first sub-buffer can be initialized * if necessary. In this case, prev_subbuf will be NULL. @@ -122,6 +124,8 @@ struct rchan_callbacks * cause relay_open() to create a single global buffer rather * than the default set of per-cpu buffers. * + * This callback is mandatory. + * * See Documentation/filesystems/relay.rst for more info. */ struct dentry *(*create_buf_file)(const char *filename, @@ -139,6 +143,8 @@ struct rchan_callbacks * channel buffer. * * The callback should return 0 if successful, negative if not. + * + * This callback is mandatory. */ int (*remove_buf_file)(struct dentry *dentry); }; diff --git a/kernel/relay.c b/kernel/relay.c index d9b8185161a8..dd4ec4ec07f3 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -271,26 +271,6 @@ static int subbuf_start_default_callback (struct rchan_buf *buf, return 1; } -/* - * create_buf_file_create() default callback. Does nothing. - */ -static struct dentry *create_buf_file_default_callback(const char *filename, - struct dentry *parent, - umode_t mode, - struct rchan_buf *buf, - int *is_global) -{ - return NULL; -} - -/* - * remove_buf_file() default callback. Does nothing. - */ -static int remove_buf_file_default_callback(struct dentry *dentry) -{ - return -EINVAL; -} - /** * wakeup_readers - wake up readers waiting on a channel * @work: contains the channel buffer @@ -467,10 +447,6 @@ static void setup_callbacks(struct rchan *chan, { if (!cb->subbuf_start) cb->subbuf_start = subbuf_start_default_callback; - if (!cb->create_buf_file) - cb->create_buf_file = create_buf_file_default_callback; - if (!cb->remove_buf_file) - cb->remove_buf_file = remove_buf_file_default_callback; chan->cb = cb; } @@ -530,7 +506,7 @@ struct rchan *relay_open(const char *base_filename, return NULL; if (subbuf_size > UINT_MAX / n_subbufs) return NULL; - if (!cb) + if (!cb || !cb->create_buf_file || !cb->remove_buf_file) return NULL; chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); -- 2.25.1