diff options
Diffstat (limited to 'kernel/relay.c')
| -rw-r--r-- | kernel/relay.c | 205 |
1 files changed, 155 insertions, 50 deletions
diff --git a/kernel/relay.c b/kernel/relay.c index 95db8c79fe8f..3b299fb3855c 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -21,6 +21,7 @@ #include <linux/vmalloc.h> #include <linux/mm.h> #include <linux/cpu.h> +#include <linux/splice.h> /* list of open channels, for cpu hotplug */ static DEFINE_MUTEX(relay_channels_mutex); @@ -121,6 +122,7 @@ static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) buf->page_array[i] = alloc_page(GFP_KERNEL); if (unlikely(!buf->page_array[i])) goto depopulate; + set_page_private(buf->page_array[i], (unsigned long)buf); } mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); if (!mem) @@ -970,43 +972,6 @@ static int subbuf_read_actor(size_t read_start, return ret; } -/* - * subbuf_send_actor - send up to one subbuf's worth of data - */ -static int subbuf_send_actor(size_t read_start, - struct rchan_buf *buf, - size_t avail, - read_descriptor_t *desc, - read_actor_t actor) -{ - unsigned long pidx, poff; - unsigned int subbuf_pages; - int ret = 0; - - subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT; - pidx = (read_start / PAGE_SIZE) % subbuf_pages; - poff = read_start & ~PAGE_MASK; - while (avail) { - struct page *p = buf->page_array[pidx]; - unsigned int len; - - len = PAGE_SIZE - poff; - if (len > avail) - len = avail; - - len = actor(desc, p, poff, len); - if (desc->error) - break; - - avail -= len; - ret += len; - poff = 0; - pidx = (pidx + 1) % subbuf_pages; - } - - return ret; -} - typedef int (*subbuf_actor_t) (size_t read_start, struct rchan_buf *buf, size_t avail, @@ -1067,19 +1032,159 @@ static ssize_t relay_file_read(struct file *filp, NULL, &desc); } -static ssize_t relay_file_sendfile(struct file *filp, - loff_t *ppos, - size_t count, - read_actor_t actor, - void *target) +static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) { - read_descriptor_t desc; - desc.written = 0; - desc.count = count; - desc.arg.data = target; - desc.error = 0; - return relay_file_read_subbufs(filp, ppos, subbuf_send_actor, - actor, &desc); + rbuf->bytes_consumed += bytes_consumed; + + if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { + relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); + rbuf->bytes_consumed %= rbuf->chan->subbuf_size; + } +} + +static void relay_pipe_buf_release(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + struct rchan_buf *rbuf; + + rbuf = (struct rchan_buf *)page_private(buf->page); + relay_consume_bytes(rbuf, buf->private); +} + +static struct pipe_buf_operations relay_pipe_buf_ops = { + .can_merge = 0, + .map = generic_pipe_buf_map, + .unmap = generic_pipe_buf_unmap, + .confirm = generic_pipe_buf_confirm, + .release = relay_pipe_buf_release, + .steal = generic_pipe_buf_steal, + .get = generic_pipe_buf_get, +}; + +/** + * subbuf_splice_actor - splice up to one subbuf's worth of data + */ +static int subbuf_splice_actor(struct file *in, + loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, + unsigned int flags, + int *nonpad_ret) +{ + unsigned int pidx, poff, total_len, subbuf_pages, ret; + struct rchan_buf *rbuf = in->private_data; + unsigned int subbuf_size = rbuf->chan->subbuf_size; + size_t read_start = ((size_t)*ppos) % rbuf->chan->alloc_size; + size_t read_subbuf = read_start / subbuf_size; + size_t padding = rbuf->padding[read_subbuf]; + size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; + struct page *pages[PIPE_BUFFERS]; + struct partial_page partial[PIPE_BUFFERS]; + struct splice_pipe_desc spd = { + .pages = pages, + .nr_pages = 0, + .partial = partial, + .flags = flags, + .ops = &relay_pipe_buf_ops, + }; + + if (rbuf->subbufs_produced == rbuf->subbufs_consumed) + return 0; + + /* + * Adjust read len, if longer than what is available + */ + if (len > (subbuf_size - read_start % subbuf_size)) + len = subbuf_size - read_start % subbuf_size; + + subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; + pidx = (read_start / PAGE_SIZE) % subbuf_pages; + poff = read_start & ~PAGE_MASK; + + for (total_len = 0; spd.nr_pages < subbuf_pages; spd.nr_pages++) { + unsigned int this_len, this_end, private; + unsigned int cur_pos = read_start + total_len; + + if (!len) + break; + + this_len = min_t(unsigned long, len, PAGE_SIZE - poff); + private = this_len; + + spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; + spd.partial[spd.nr_pages].offset = poff; + + this_end = cur_pos + this_len; + if (this_end >= nonpad_end) { + this_len = nonpad_end - cur_pos; + private = this_len + padding; + } + spd.partial[spd.nr_pages].len = this_len; + spd.partial[spd.nr_pages].private = private; + + len -= this_len; + total_len += this_len; + poff = 0; + pidx = (pidx + 1) % subbuf_pages; + + if (this_end >= nonpad_end) { + spd.nr_pages++; + break; + } + } + + if (!spd.nr_pages) + return 0; + + ret = *nonpad_ret = splice_to_pipe(pipe, &spd); + if (ret < 0 || ret < total_len) + return ret; + + if (read_start + ret == nonpad_end) + ret += padding; + + return ret; +} + +static ssize_t relay_file_splice_read(struct file *in, + loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, + unsigned int flags) +{ + ssize_t spliced; + int ret; + int nonpad_ret = 0; + + ret = 0; + spliced = 0; + + while (len) { + ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); + if (ret < 0) + break; + else if (!ret) { + if (spliced) + break; + if (flags & SPLICE_F_NONBLOCK) { + ret = -EAGAIN; + break; + } + } + + *ppos += ret; + if (ret > len) + len = 0; + else + len -= ret; + spliced += nonpad_ret; + nonpad_ret = 0; + } + + if (spliced) + return spliced; + + return ret; } const struct file_operations relay_file_operations = { @@ -1089,7 +1194,7 @@ const struct file_operations relay_file_operations = { .read = relay_file_read, .llseek = no_llseek, .release = relay_file_release, - .sendfile = relay_file_sendfile, + .splice_read = relay_file_splice_read, }; EXPORT_SYMBOL_GPL(relay_file_operations); |