relay: remove unused relay_late_setup_files

The last use of relay_late_setup_files() was removed in 2018 by commit
2b47733045aa ("drm/i915/guc: Merge log relay file and channel creation")

Remove it and the helper it used.

relay_late_setup_files() was used for eventually registering 'buffer only'
channels.  With it gone, delete the docs that explain how to do that.
Which suggests it should be possible to lose the 'has_base_filename'
flags.

(Are there any other uses??)

Link: https://lkml.kernel.org/r/20250418234932.490863-1-linux@treblig.org
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/filesystems/relay.rst b/Documentation/filesystems/relay.rst
index 04ad083cfe621482cf89496ecce402c8bd54c76f..292ba8492aeb4863a30737fec6c018caa655f938 100644 (file)
--- a/Documentation/filesystems/relay.rst
+++ b/Documentation/filesystems/relay.rst
@@ -301,16 +301,6 @@ user-defined data with a channel, and is immediately available
 (including in create_buf_file()) via chan->private_data or
 buf->chan->private_data.
 
-Buffer-only channels
---------------------
-
-These channels have no files associated and can be created with
-relay_open(NULL, NULL, ...). Such channels are useful in scenarios such
-as when doing early tracing in the kernel, before the VFS is up. In these
-cases, one may open a buffer-only channel and then call
-relay_late_setup_files() when the kernel is ready to handle files,
-to expose the buffered data to the userspace.
-
 Channel 'modes'
 ---------------
 

diff --git a/include/linux/relay.h b/include/linux/relay.h
index 72b876dd5cb8e0995495a139e8c7c579de8c8d8d..b3224111d074cc0665cacf5ffd25a5d1747167b9 100644 (file)
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -159,9 +159,6 @@ struct rchan *relay_open(const char *base_filename,
                         size_t n_subbufs,
                         const struct rchan_callbacks *cb,
                         void *private_data);
-extern int relay_late_setup_files(struct rchan *chan,
-                                 const char *base_filename,
-                                 struct dentry *parent);
 extern void relay_close(struct rchan *chan);
 extern void relay_flush(struct rchan *chan);
 extern void relay_subbufs_consumed(struct rchan *chan,

diff --git a/kernel/relay.c b/kernel/relay.c
index 5ac7e711e4b65005533faca3a2a85eba00897b42..c0c93a04d4ce926937dfbc9098e1d9df9821853e 100644 (file)
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -452,7 +452,7 @@ int relay_prepare_cpu(unsigned int cpu)
 
 /**
  *     relay_open - create a new relay channel
- *     @base_filename: base name of files to create, %NULL for buffering only
+ *     @base_filename: base name of files to create
  *     @parent: dentry of parent directory, %NULL for root directory or buffer
  *     @subbuf_size: size of sub-buffers
  *     @n_subbufs: number of sub-buffers
@@ -465,10 +465,6 @@ int relay_prepare_cpu(unsigned int cpu)
  *     attributes specified.  The created channel buffer files
  *     will be named base_filename0...base_filenameN-1.  File
  *     permissions will be %S_IRUSR.
- *
- *     If opening a buffer (@parent = NULL) that you later wish to register
- *     in a filesystem, call relay_late_setup_files() once the @parent dentry
- *     is available.
  */
 struct rchan *relay_open(const char *base_filename,
                         struct dentry *parent,
@@ -540,111 +536,6 @@ struct rchan_percpu_buf_dispatcher {
        struct dentry *dentry;
 };
 
-/* Called in atomic context. */
-static void __relay_set_buf_dentry(void *info)
-{
-       struct rchan_percpu_buf_dispatcher *p = info;
-
-       relay_set_buf_dentry(p->buf, p->dentry);
-}
-
-/**
- *     relay_late_setup_files - triggers file creation
- *     @chan: channel to operate on
- *     @base_filename: base name of files to create
- *     @parent: dentry of parent directory, %NULL for root directory
- *
- *     Returns 0 if successful, non-zero otherwise.
- *
- *     Use to setup files for a previously buffer-only channel created
- *     by relay_open() with a NULL parent dentry.
- *
- *     For example, this is useful for perfomring early tracing in kernel,
- *     before VFS is up and then exposing the early results once the dentry
- *     is available.
- */
-int relay_late_setup_files(struct rchan *chan,
-                          const char *base_filename,
-                          struct dentry *parent)
-{
-       int err = 0;
-       unsigned int i, curr_cpu;
-       unsigned long flags;
-       struct dentry *dentry;
-       struct rchan_buf *buf;
-       struct rchan_percpu_buf_dispatcher disp;
-
-       if (!chan || !base_filename)
-               return -EINVAL;
-
-       strscpy(chan->base_filename, base_filename, NAME_MAX);
-
-       mutex_lock(&relay_channels_mutex);
-       /* Is chan already set up? */
-       if (unlikely(chan->has_base_filename)) {
-               mutex_unlock(&relay_channels_mutex);
-               return -EEXIST;
-       }
-       chan->has_base_filename = 1;
-       chan->parent = parent;
-
-       if (chan->is_global) {
-               err = -EINVAL;
-               buf = *per_cpu_ptr(chan->buf, 0);
-               if (!WARN_ON_ONCE(!buf)) {
-                       dentry = relay_create_buf_file(chan, buf, 0);
-                       if (dentry && !WARN_ON_ONCE(!chan->is_global)) {
-                               relay_set_buf_dentry(buf, dentry);
-                               err = 0;
-                       }
-               }
-               mutex_unlock(&relay_channels_mutex);
-               return err;
-       }
-
-       curr_cpu = get_cpu();
-       /*
-        * The CPU hotplug notifier ran before us and created buffers with
-        * no files associated. So it's safe to call relay_setup_buf_file()
-        * on all currently online CPUs.
-        */
-       for_each_online_cpu(i) {
-               buf = *per_cpu_ptr(chan->buf, i);
-               if (unlikely(!buf)) {
-                       WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n");
-                       err = -EINVAL;
-                       break;
-               }
-
-               dentry = relay_create_buf_file(chan, buf, i);
-               if (unlikely(!dentry)) {
-                       err = -EINVAL;
-                       break;
-               }
-
-               if (curr_cpu == i) {
-                       local_irq_save(flags);
-                       relay_set_buf_dentry(buf, dentry);
-                       local_irq_restore(flags);
-               } else {
-                       disp.buf = buf;
-                       disp.dentry = dentry;
-                       smp_mb();
-                       /* relay_channels_mutex must be held, so wait. */
-                       err = smp_call_function_single(i,
-                                                      __relay_set_buf_dentry,
-                                                      &disp, 1);
-               }
-               if (unlikely(err))
-                       break;
-       }
-       put_cpu();
-       mutex_unlock(&relay_channels_mutex);
-
-       return err;
-}
-EXPORT_SYMBOL_GPL(relay_late_setup_files);
-
 /**
  *     relay_switch_subbuf - switch to a new sub-buffer
  *     @buf: channel buffer