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SubjectRe: [PATCH 3/3] relay - add channel flags
On Tue, 23 Sep 2008 00:27:56 -0500
Tom Zanussi <zanussi@comcast.net> wrote:

> Add channel flags to relay, remove global callback param.
>
> relay should probably have had a flags param from the beginning; it
> wasn't originally added because it wasn't originally needed - it
> probably would have helped avoid some of the callback contortions
> that were added due to a lack of flags. This adds them and does a
> small amount of low-hanging cleanup, and is also in preparation for
> some new flags in future patches.
>
> Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
>
> diff --git a/block/blktrace.c b/block/blktrace.c
> index eb9651c..150c5f7 100644
> --- a/block/blktrace.c
> +++ b/block/blktrace.c
> @@ -356,8 +356,7 @@ static int blk_remove_buf_file_callback(struct dentry *dentry)
> static struct dentry *blk_create_buf_file_callback(const char *filename,
> struct dentry *parent,
> int mode,
> - struct rchan_buf *buf,
> - int *is_global)
> + struct rchan_buf *buf)
> {
> return debugfs_create_file(filename, mode, parent, buf,
> &relay_file_operations);
> @@ -424,7 +423,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
> goto err;
>
> bt->rchan = relay_open("trace", dir, buts->buf_size,
> - buts->buf_nr, &blk_relay_callbacks, bt);
> + buts->buf_nr, &blk_relay_callbacks, bt, 0UL);
> if (!bt->rchan)
> goto err;
>
> diff --git a/include/linux/relay.h b/include/linux/relay.h
> index 52e4d61..18fd269 100644
> --- a/include/linux/relay.h
> +++ b/include/linux/relay.h
> @@ -25,7 +25,13 @@
> /*
> * Tracks changes to rchan/rchan_buf structs
> */
> -#define RELAYFS_CHANNEL_VERSION 7
> +#define RELAYFS_CHANNEL_VERSION 8

What is the significance of this change? Does it affect the
kernel<->userspace interface? Is it back-compatible with existing
userspace?


> +/*
> + * relay channel flags
> + */
> +#define RCHAN_MODE_OVERWRITE 0x00000001 /* 'flight' mode */
> +#define RCHAN_GLOBAL_BUFFER 0x00000002 /* not using per-cpu */
>
>
> ...
>
> @@ -480,7 +478,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
> buf->cpu = cpu;
> __relay_reset(buf, 1);
>
> - if(chan->is_global) {
> + if(chan->flags & RCHAN_GLOBAL_BUFFER) {

Please use checkpatch. It's a little thing, but it's so easy to fix..

> chan->buf[0] = buf;
> buf->cpu = 0;
> }
>
> ...


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