Commit 371e0388 authored by Jani Nikula's avatar Jani Nikula Committed by Linus Torvalds
Browse files

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: default avatarJani Nikula <jani.nikula@intel.com>
Suggested-by: default avatarChristoph Hellwig <hch@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6f8f2544

include/linux/relay.h

+6 −0
Original line number Diff line number Diff line
@@ -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);

};

kernel/relay.c

+1 −25
Original line number Diff line number Diff line
@@ -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);