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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: Tom Zanussi <zanussi@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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03d78d11d9
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@ -86,7 +86,8 @@ static void buf_unmapped_default_callback(struct rchan_buf *buf,
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static struct dentry *create_buf_file_default_callback(const char *filename,
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struct dentry *parent,
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int mode,
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struct rchan_buf *buf)
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struct rchan_buf *buf,
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int *is_global)
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{
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return relayfs_create_file(filename, parent, mode,
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&relayfs_file_operations, buf);
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@ -170,14 +171,16 @@ static inline void __relay_reset(struct rchan_buf *buf, unsigned int init)
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void relay_reset(struct rchan *chan)
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{
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unsigned int i;
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struct rchan_buf *prev = NULL;
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if (!chan)
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return;
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for (i = 0; i < NR_CPUS; i++) {
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if (!chan->buf[i])
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continue;
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if (!chan->buf[i] || chan->buf[i] == prev)
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break;
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__relay_reset(chan->buf[i], 0);
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prev = chan->buf[i];
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}
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}
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@ -188,18 +191,22 @@ void relay_reset(struct rchan *chan)
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*/
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static struct rchan_buf *relay_open_buf(struct rchan *chan,
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const char *filename,
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struct dentry *parent)
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struct dentry *parent,
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int *is_global)
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{
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struct rchan_buf *buf;
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struct dentry *dentry;
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if (*is_global)
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return chan->buf[0];
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buf = relay_create_buf(chan);
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if (!buf)
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return NULL;
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/* Create file in fs */
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dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR,
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buf);
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buf, is_global);
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if (!dentry) {
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relay_destroy_buf(buf);
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return NULL;
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@ -273,6 +280,7 @@ struct rchan *relay_open(const char *base_filename,
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unsigned int i;
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struct rchan *chan;
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char *tmpname;
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int is_global = 0;
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if (!base_filename)
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return NULL;
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@ -297,7 +305,8 @@ struct rchan *relay_open(const char *base_filename,
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for_each_online_cpu(i) {
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sprintf(tmpname, "%s%d", base_filename, i);
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chan->buf[i] = relay_open_buf(chan, tmpname, parent);
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chan->buf[i] = relay_open_buf(chan, tmpname, parent,
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&is_global);
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chan->buf[i]->cpu = i;
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if (!chan->buf[i])
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goto free_bufs;
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@ -311,6 +320,8 @@ free_bufs:
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if (!chan->buf[i])
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break;
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relay_close_buf(chan->buf[i]);
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if (is_global)
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break;
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}
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kfree(tmpname);
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@ -420,14 +431,16 @@ void relay_destroy_channel(struct kref *kref)
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void relay_close(struct rchan *chan)
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{
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unsigned int i;
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struct rchan_buf *prev = NULL;
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if (!chan)
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return;
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for (i = 0; i < NR_CPUS; i++) {
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if (!chan->buf[i])
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continue;
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if (!chan->buf[i] || chan->buf[i] == prev)
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break;
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relay_close_buf(chan->buf[i]);
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prev = chan->buf[i];
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}
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if (chan->last_toobig)
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@ -447,14 +460,16 @@ void relay_close(struct rchan *chan)
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void relay_flush(struct rchan *chan)
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{
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unsigned int i;
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struct rchan_buf *prev = NULL;
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if (!chan)
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return;
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for (i = 0; i < NR_CPUS; i++) {
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if (!chan->buf[i])
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continue;
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if (!chan->buf[i] || chan->buf[i] == prev)
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break;
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relay_switch_subbuf(chan->buf[i], 0);
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prev = chan->buf[i];
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}
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}
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@ -116,6 +116,7 @@ struct rchan_callbacks
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* @parent: the parent of the file to create
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* @mode: the mode of the file to create
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* @buf: the channel buffer
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* @is_global: outparam - set non-zero if the buffer should be global
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*
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* Called during relay_open(), once for each per-cpu buffer,
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* to allow the client to create a file to be used to
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@ -126,12 +127,17 @@ struct rchan_callbacks
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* The callback should return the dentry of the file created
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* to represent the relay buffer.
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*
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* Setting the is_global outparam to a non-zero value will
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* cause relay_open() to create a single global buffer rather
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* than the default set of per-cpu buffers.
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*
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* See Documentation/filesystems/relayfs.txt for more info.
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*/
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struct dentry *(*create_buf_file)(const char *filename,
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struct dentry *parent,
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int mode,
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struct rchan_buf *buf);
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struct rchan_buf *buf,
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int *is_global);
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/*
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* remove_buf_file - remove file representing a relayfs channel buffer
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