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: Tom Zanussi <[email protected]>
---
fs/relayfs/relay.c | 35 +++++++++++++++++++++++++----------
include/linux/relayfs_fs.h | 8 +++++++-
2 files changed, 32 insertions(+), 11 deletions(-)
diff --git a/fs/relayfs/relay.c b/fs/relayfs/relay.c
--- a/fs/relayfs/relay.c
+++ b/fs/relayfs/relay.c
@@ -86,7 +86,8 @@ static void buf_unmapped_default_callbac
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
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 *bas
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 *bas
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);
@@ -421,14 +432,16 @@ void relay_destroy_channel(struct 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];
}
kref_put(&chan->kref, relay_destroy_channel);
@@ -443,14 +456,16 @@ 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];
}
}
diff --git a/include/linux/relayfs_fs.h b/include/linux/relayfs_fs.h
--- a/include/linux/relayfs_fs.h
+++ b/include/linux/relayfs_fs.h
@@ -115,6 +115,7 @@ 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
@@ -125,12 +126,17 @@ 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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