Commit e6c08367 authored by Tom Zanussi's avatar Tom Zanussi Committed by Linus Torvalds
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[PATCH] relayfs: add support for global relay buffers 



This patch adds the optional is_global outparam to the create_buf_file()
callback.  This can be used by clients to create a single global relayfs
buffer instead of the default per-cpu buffers.  This was suggested as being
useful for certain debugging applications where it's more convenient to be
able to get all the data from a single channel without having to go to the
bother of dealing with per-cpu files.

Signed-off-by: default avatarTom Zanussi <zanussi@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 03d78d11

fs/relayfs/relay.c

+25 −10
Original line number Diff line number Diff line
@@ -86,7 +86,8 @@ static void buf_unmapped_default_callback(struct rchan_buf *buf, 
static struct dentry *create_buf_file_default_callback(const char *filename,

						       struct dentry *parent,

						       int mode,

						       struct rchan_buf *buf)

						       struct rchan_buf *buf,

						       int *is_global)

{

	return relayfs_create_file(filename, parent, mode,

				   &relayfs_file_operations, buf);
@@ -170,14 +171,16 @@ static inline void __relay_reset(struct rchan_buf *buf, unsigned int init) 
void relay_reset(struct rchan *chan)

{

	unsigned int i;

	struct rchan_buf *prev = NULL;



	if (!chan)

		return;



	for (i = 0; i < NR_CPUS; i++) {

		if (!chan->buf[i])

			continue;

		if (!chan->buf[i] || chan->buf[i] == prev)

			break;

		__relay_reset(chan->buf[i], 0);

		prev = chan->buf[i];

	}

}
@@ -188,18 +191,22 @@ void relay_reset(struct rchan *chan) 
 */

static struct rchan_buf *relay_open_buf(struct rchan *chan,

					const char *filename,

					struct dentry *parent)

					struct dentry *parent,

					int *is_global)

{

	struct rchan_buf *buf;

	struct dentry *dentry;



	if (*is_global)

		return chan->buf[0];



 	buf = relay_create_buf(chan);

 	if (!buf)

 		return NULL;



	/* Create file in fs */

 	dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR,

 					   buf);

 					   buf, is_global);

 	if (!dentry) {

 		relay_destroy_buf(buf);

		return NULL;
@@ -273,6 +280,7 @@ struct rchan *relay_open(const char *base_filename, 
	unsigned int i;

	struct rchan *chan;

	char *tmpname;

	int is_global = 0;



	if (!base_filename)

		return NULL;
@@ -297,7 +305,8 @@ struct rchan *relay_open(const char *base_filename, 


	for_each_online_cpu(i) {

		sprintf(tmpname, "%s%d", base_filename, i);

		chan->buf[i] = relay_open_buf(chan, tmpname, parent);

		chan->buf[i] = relay_open_buf(chan, tmpname, parent,

					      &is_global);

		chan->buf[i]->cpu = i;

		if (!chan->buf[i])

			goto free_bufs;
@@ -311,6 +320,8 @@ free_bufs: 
		if (!chan->buf[i])

			break;

		relay_close_buf(chan->buf[i]);

		if (is_global)

			break;

	}

	kfree(tmpname);
@@ -420,14 +431,16 @@ void relay_destroy_channel(struct kref *kref) 
void relay_close(struct rchan *chan)

{

	unsigned int i;

	struct rchan_buf *prev = NULL;



	if (!chan)

		return;



	for (i = 0; i < NR_CPUS; i++) {

		if (!chan->buf[i])

			continue;

		if (!chan->buf[i] || chan->buf[i] == prev)

			break;

		relay_close_buf(chan->buf[i]);

		prev = chan->buf[i];

	}



	if (chan->last_toobig)
@@ -447,14 +460,16 @@ void relay_close(struct rchan *chan) 
void relay_flush(struct rchan *chan)

{

	unsigned int i;

	struct rchan_buf *prev = NULL;



	if (!chan)

		return;



	for (i = 0; i < NR_CPUS; i++) {

		if (!chan->buf[i])

			continue;

		if (!chan->buf[i] || chan->buf[i] == prev)

			break;

		relay_switch_subbuf(chan->buf[i], 0);

		prev = chan->buf[i];

	}

}

include/linux/relayfs_fs.h

+7 −1
Original line number Diff line number Diff line
@@ -116,6 +116,7 @@ struct rchan_callbacks 
	 * @parent: the parent of the file to create

	 * @mode: the mode of the file to create

	 * @buf: the channel buffer

	 * @is_global: outparam - set non-zero if the buffer should be global

	 *

	 * Called during relay_open(), once for each per-cpu buffer,

	 * to allow the client to create a file to be used to
@@ -126,12 +127,17 @@ struct rchan_callbacks 
	 * The callback should return the dentry of the file created

	 * to represent the relay buffer.

	 *

	 * Setting the is_global outparam to a non-zero value will

	 * cause relay_open() to create a single global buffer rather

	 * than the default set of per-cpu buffers.

	 *

	 * See Documentation/filesystems/relayfs.txt for more info.

	 */

	struct dentry *(*create_buf_file)(const char *filename,

					  struct dentry *parent,

					  int mode,

					  struct rchan_buf *buf);

					  struct rchan_buf *buf,

					  int *is_global);



	/*

	 * remove_buf_file - remove file representing a relayfs channel buffer

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