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@@ -0,0 +1,919 @@
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+/*
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+ * Public API and common code for kernel->userspace relay file support.
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+ *
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+ * See Documentation/filesystems/relayfs.txt for an overview of relayfs.
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+ *
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+ * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
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+ * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
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+ *
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+ * Moved to kernel/relay.c by Paul Mundt, 2006.
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+ *
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+ * This file is released under the GPL.
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+ */
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+#include <linux/errno.h>
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+#include <linux/stddef.h>
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+#include <linux/slab.h>
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+#include <linux/module.h>
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+#include <linux/string.h>
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+#include <linux/relay.h>
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+#include <linux/vmalloc.h>
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+#include <linux/mm.h>
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+
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+/*
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+ * close() vm_op implementation for relay file mapping.
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+ */
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+static void relay_file_mmap_close(struct vm_area_struct *vma)
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+{
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+ struct rchan_buf *buf = vma->vm_private_data;
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+ buf->chan->cb->buf_unmapped(buf, vma->vm_file);
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+}
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+
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+/*
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+ * nopage() vm_op implementation for relay file mapping.
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+ */
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+static struct page *relay_buf_nopage(struct vm_area_struct *vma,
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+ unsigned long address,
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+ int *type)
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+{
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+ struct page *page;
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+ struct rchan_buf *buf = vma->vm_private_data;
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+ unsigned long offset = address - vma->vm_start;
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+
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+ if (address > vma->vm_end)
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+ return NOPAGE_SIGBUS; /* Disallow mremap */
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+ if (!buf)
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+ return NOPAGE_OOM;
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+
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+ page = vmalloc_to_page(buf->start + offset);
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+ if (!page)
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+ return NOPAGE_OOM;
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+ get_page(page);
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+
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+ if (type)
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+ *type = VM_FAULT_MINOR;
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+
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+ return page;
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+}
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+
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+/*
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+ * vm_ops for relay file mappings.
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+ */
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+static struct vm_operations_struct relay_file_mmap_ops = {
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+ .nopage = relay_buf_nopage,
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+ .close = relay_file_mmap_close,
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+};
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+
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+/**
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+ * relay_mmap_buf: - mmap channel buffer to process address space
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+ * @buf: relay channel buffer
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+ * @vma: vm_area_struct describing memory to be mapped
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+ *
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+ * Returns 0 if ok, negative on error
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+ *
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+ * Caller should already have grabbed mmap_sem.
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+ */
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+int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
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+{
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+ unsigned long length = vma->vm_end - vma->vm_start;
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+ struct file *filp = vma->vm_file;
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+
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+ if (!buf)
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+ return -EBADF;
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+
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+ if (length != (unsigned long)buf->chan->alloc_size)
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+ return -EINVAL;
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+
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+ vma->vm_ops = &relay_file_mmap_ops;
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+ vma->vm_private_data = buf;
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+ buf->chan->cb->buf_mapped(buf, filp);
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+
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+ return 0;
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+}
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+
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+/**
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+ * relay_alloc_buf - allocate a channel buffer
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+ * @buf: the buffer struct
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+ * @size: total size of the buffer
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+ *
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+ * Returns a pointer to the resulting buffer, NULL if unsuccessful
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+ */
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+static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size)
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+{
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+ void *mem;
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+ unsigned int i, j, n_pages;
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+
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+ size = PAGE_ALIGN(size);
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+ n_pages = size >> PAGE_SHIFT;
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+
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+ buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
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+ if (!buf->page_array)
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+ return NULL;
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+
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+ for (i = 0; i < n_pages; i++) {
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+ buf->page_array[i] = alloc_page(GFP_KERNEL);
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+ if (unlikely(!buf->page_array[i]))
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+ goto depopulate;
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+ }
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+ mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
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+ if (!mem)
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+ goto depopulate;
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+
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+ memset(mem, 0, size);
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+ buf->page_count = n_pages;
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+ return mem;
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+
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+depopulate:
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+ for (j = 0; j < i; j++)
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+ __free_page(buf->page_array[j]);
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+ kfree(buf->page_array);
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+ return NULL;
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+}
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+
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+/**
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+ * relay_create_buf - allocate and initialize a channel buffer
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+ * @alloc_size: size of the buffer to allocate
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+ * @n_subbufs: number of sub-buffers in the channel
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+ *
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+ * Returns channel buffer if successful, NULL otherwise
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+ */
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+struct rchan_buf *relay_create_buf(struct rchan *chan)
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+{
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+ struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL);
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+ if (!buf)
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+ return NULL;
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+
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+ buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
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+ if (!buf->padding)
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+ goto free_buf;
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+
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+ buf->start = relay_alloc_buf(buf, chan->alloc_size);
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+ if (!buf->start)
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+ goto free_buf;
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+
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+ buf->chan = chan;
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+ kref_get(&buf->chan->kref);
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+ return buf;
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+
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+free_buf:
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+ kfree(buf->padding);
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+ kfree(buf);
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+ return NULL;
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+}
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+
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+/**
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+ * relay_destroy_channel - free the channel struct
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+ *
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+ * Should only be called from kref_put().
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+ */
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+void relay_destroy_channel(struct kref *kref)
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+{
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+ struct rchan *chan = container_of(kref, struct rchan, kref);
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+ kfree(chan);
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+}
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+
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+/**
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+ * relay_destroy_buf - destroy an rchan_buf struct and associated buffer
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+ * @buf: the buffer struct
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+ */
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+void relay_destroy_buf(struct rchan_buf *buf)
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+{
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+ struct rchan *chan = buf->chan;
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+ unsigned int i;
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+
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+ if (likely(buf->start)) {
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+ vunmap(buf->start);
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+ for (i = 0; i < buf->page_count; i++)
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+ __free_page(buf->page_array[i]);
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+ kfree(buf->page_array);
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+ }
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+ kfree(buf->padding);
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+ kfree(buf);
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+ kref_put(&chan->kref, relay_destroy_channel);
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+}
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+
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+/**
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+ * relay_remove_buf - remove a channel buffer
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+ *
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+ * Removes the file from the fileystem, which also frees the
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+ * rchan_buf_struct and the channel buffer. Should only be called from
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+ * kref_put().
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+ */
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+void relay_remove_buf(struct kref *kref)
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+{
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+ struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
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+ buf->chan->cb->remove_buf_file(buf->dentry);
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+ relay_destroy_buf(buf);
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+}
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+
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+/**
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+ * relay_buf_empty - boolean, is the channel buffer empty?
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+ * @buf: channel buffer
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+ *
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+ * Returns 1 if the buffer is empty, 0 otherwise.
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+ */
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+int relay_buf_empty(struct rchan_buf *buf)
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+{
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+ return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
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+}
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+EXPORT_SYMBOL_GPL(relay_buf_empty);
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+
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+/**
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+ * relay_buf_full - boolean, is the channel buffer full?
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+ * @buf: channel buffer
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+ *
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+ * Returns 1 if the buffer is full, 0 otherwise.
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+ */
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+int relay_buf_full(struct rchan_buf *buf)
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+{
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+ size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
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+ return (ready >= buf->chan->n_subbufs) ? 1 : 0;
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+}
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+EXPORT_SYMBOL_GPL(relay_buf_full);
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+
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+/*
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+ * High-level relay kernel API and associated functions.
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+ */
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+
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+/*
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+ * rchan_callback implementations defining default channel behavior. Used
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+ * in place of corresponding NULL values in client callback struct.
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+ */
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+
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+/*
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+ * subbuf_start() default callback. Does nothing.
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+ */
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+static int subbuf_start_default_callback (struct rchan_buf *buf,
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+ void *subbuf,
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+ void *prev_subbuf,
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+ size_t prev_padding)
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+{
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+ if (relay_buf_full(buf))
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+ return 0;
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+
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+ return 1;
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+}
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+
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+/*
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+ * buf_mapped() default callback. Does nothing.
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+ */
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+static void buf_mapped_default_callback(struct rchan_buf *buf,
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+ struct file *filp)
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+{
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+}
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+
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+/*
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+ * buf_unmapped() default callback. Does nothing.
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+ */
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+static void buf_unmapped_default_callback(struct rchan_buf *buf,
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+ struct file *filp)
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+{
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+}
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+
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+/*
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+ * create_buf_file_create() default callback. Does nothing.
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+ */
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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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+ int *is_global)
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+{
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+ return NULL;
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+}
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+
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+/*
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+ * remove_buf_file() default callback. Does nothing.
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+ */
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+static int remove_buf_file_default_callback(struct dentry *dentry)
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+{
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+ return -EINVAL;
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+}
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+
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+/* relay channel default callbacks */
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+static struct rchan_callbacks default_channel_callbacks = {
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+ .subbuf_start = subbuf_start_default_callback,
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+ .buf_mapped = buf_mapped_default_callback,
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+ .buf_unmapped = buf_unmapped_default_callback,
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+ .create_buf_file = create_buf_file_default_callback,
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+ .remove_buf_file = remove_buf_file_default_callback,
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+};
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+
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+/**
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+ * wakeup_readers - wake up readers waiting on a channel
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+ * @private: the channel buffer
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+ *
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+ * This is the work function used to defer reader waking. The
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+ * reason waking is deferred is that calling directly from write
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+ * causes problems if you're writing from say the scheduler.
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+ */
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+static void wakeup_readers(void *private)
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+{
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+ struct rchan_buf *buf = private;
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+ wake_up_interruptible(&buf->read_wait);
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+}
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+
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+/**
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+ * __relay_reset - reset a channel buffer
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+ * @buf: the channel buffer
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+ * @init: 1 if this is a first-time initialization
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+ *
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+ * See relay_reset for description of effect.
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+ */
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+static inline void __relay_reset(struct rchan_buf *buf, unsigned int init)
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+{
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+ size_t i;
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+
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+ if (init) {
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+ init_waitqueue_head(&buf->read_wait);
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+ kref_init(&buf->kref);
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+ INIT_WORK(&buf->wake_readers, NULL, NULL);
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+ } else {
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+ cancel_delayed_work(&buf->wake_readers);
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+ flush_scheduled_work();
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+ }
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+
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+ buf->subbufs_produced = 0;
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+ buf->subbufs_consumed = 0;
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+ buf->bytes_consumed = 0;
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+ buf->finalized = 0;
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+ buf->data = buf->start;
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+ buf->offset = 0;
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+
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+ for (i = 0; i < buf->chan->n_subbufs; i++)
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+ buf->padding[i] = 0;
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+
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+ buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
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+}
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+
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+/**
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+ * relay_reset - reset the channel
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+ * @chan: the channel
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+ *
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+ * This has the effect of erasing all data from all channel buffers
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+ * and restarting the channel in its initial state. The buffers
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+ * are not freed, so any mappings are still in effect.
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+ *
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+ * NOTE: Care should be taken that the channel isn't actually
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+ * being used by anything when this call is made.
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+ */
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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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+
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+ if (!chan)
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+ return;
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+
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+ for (i = 0; i < NR_CPUS; i++) {
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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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+EXPORT_SYMBOL_GPL(relay_reset);
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+
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+/**
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+ * relay_open_buf - create a new relay channel buffer
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+ *
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+ * Internal - used by relay_open().
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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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+ 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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+
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+ if (*is_global)
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+ return chan->buf[0];
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+
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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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+
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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, 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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+ }
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+
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+ buf->dentry = dentry;
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+ __relay_reset(buf, 1);
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+
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+ return buf;
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+}
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+
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+/**
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+ * relay_close_buf - close a channel buffer
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+ * @buf: channel buffer
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+ *
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+ * Marks the buffer finalized and restores the default callbacks.
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+ * The channel buffer and channel buffer data structure are then freed
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+ * automatically when the last reference is given up.
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+ */
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+static inline void relay_close_buf(struct rchan_buf *buf)
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+{
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+ buf->finalized = 1;
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+ cancel_delayed_work(&buf->wake_readers);
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+ flush_scheduled_work();
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+ kref_put(&buf->kref, relay_remove_buf);
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+}
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+
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+static inline void setup_callbacks(struct rchan *chan,
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+ struct rchan_callbacks *cb)
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+{
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+ if (!cb) {
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+ chan->cb = &default_channel_callbacks;
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+ return;
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+ }
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+
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|
|
+ if (!cb->subbuf_start)
|
|
|
+ cb->subbuf_start = subbuf_start_default_callback;
|
|
|
+ if (!cb->buf_mapped)
|
|
|
+ cb->buf_mapped = buf_mapped_default_callback;
|
|
|
+ if (!cb->buf_unmapped)
|
|
|
+ cb->buf_unmapped = buf_unmapped_default_callback;
|
|
|
+ if (!cb->create_buf_file)
|
|
|
+ cb->create_buf_file = create_buf_file_default_callback;
|
|
|
+ if (!cb->remove_buf_file)
|
|
|
+ cb->remove_buf_file = remove_buf_file_default_callback;
|
|
|
+ chan->cb = cb;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_open - create a new relay channel
|
|
|
+ * @base_filename: base name of files to create
|
|
|
+ * @parent: dentry of parent directory, NULL for root directory
|
|
|
+ * @subbuf_size: size of sub-buffers
|
|
|
+ * @n_subbufs: number of sub-buffers
|
|
|
+ * @cb: client callback functions
|
|
|
+ *
|
|
|
+ * Returns channel pointer if successful, NULL otherwise.
|
|
|
+ *
|
|
|
+ * Creates a channel buffer for each cpu using the sizes and
|
|
|
+ * attributes specified. The created channel buffer files
|
|
|
+ * will be named base_filename0...base_filenameN-1. File
|
|
|
+ * permissions will be S_IRUSR.
|
|
|
+ */
|
|
|
+struct rchan *relay_open(const char *base_filename,
|
|
|
+ struct dentry *parent,
|
|
|
+ size_t subbuf_size,
|
|
|
+ size_t n_subbufs,
|
|
|
+ struct rchan_callbacks *cb)
|
|
|
+{
|
|
|
+ unsigned int i;
|
|
|
+ struct rchan *chan;
|
|
|
+ char *tmpname;
|
|
|
+ int is_global = 0;
|
|
|
+
|
|
|
+ if (!base_filename)
|
|
|
+ return NULL;
|
|
|
+
|
|
|
+ if (!(subbuf_size && n_subbufs))
|
|
|
+ return NULL;
|
|
|
+
|
|
|
+ chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL);
|
|
|
+ if (!chan)
|
|
|
+ return NULL;
|
|
|
+
|
|
|
+ chan->version = RELAYFS_CHANNEL_VERSION;
|
|
|
+ chan->n_subbufs = n_subbufs;
|
|
|
+ chan->subbuf_size = subbuf_size;
|
|
|
+ chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
|
|
|
+ setup_callbacks(chan, cb);
|
|
|
+ kref_init(&chan->kref);
|
|
|
+
|
|
|
+ tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL);
|
|
|
+ if (!tmpname)
|
|
|
+ goto free_chan;
|
|
|
+
|
|
|
+ for_each_online_cpu(i) {
|
|
|
+ sprintf(tmpname, "%s%d", base_filename, i);
|
|
|
+ chan->buf[i] = relay_open_buf(chan, tmpname, parent,
|
|
|
+ &is_global);
|
|
|
+ if (!chan->buf[i])
|
|
|
+ goto free_bufs;
|
|
|
+
|
|
|
+ chan->buf[i]->cpu = i;
|
|
|
+ }
|
|
|
+
|
|
|
+ kfree(tmpname);
|
|
|
+ return chan;
|
|
|
+
|
|
|
+free_bufs:
|
|
|
+ for (i = 0; i < NR_CPUS; i++) {
|
|
|
+ if (!chan->buf[i])
|
|
|
+ break;
|
|
|
+ relay_close_buf(chan->buf[i]);
|
|
|
+ if (is_global)
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ kfree(tmpname);
|
|
|
+
|
|
|
+free_chan:
|
|
|
+ kref_put(&chan->kref, relay_destroy_channel);
|
|
|
+ return NULL;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(relay_open);
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_switch_subbuf - switch to a new sub-buffer
|
|
|
+ * @buf: channel buffer
|
|
|
+ * @length: size of current event
|
|
|
+ *
|
|
|
+ * Returns either the length passed in or 0 if full.
|
|
|
+ *
|
|
|
+ * Performs sub-buffer-switch tasks such as invoking callbacks,
|
|
|
+ * updating padding counts, waking up readers, etc.
|
|
|
+ */
|
|
|
+size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
|
|
|
+{
|
|
|
+ void *old, *new;
|
|
|
+ size_t old_subbuf, new_subbuf;
|
|
|
+
|
|
|
+ if (unlikely(length > buf->chan->subbuf_size))
|
|
|
+ goto toobig;
|
|
|
+
|
|
|
+ if (buf->offset != buf->chan->subbuf_size + 1) {
|
|
|
+ buf->prev_padding = buf->chan->subbuf_size - buf->offset;
|
|
|
+ old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
|
|
|
+ buf->padding[old_subbuf] = buf->prev_padding;
|
|
|
+ buf->subbufs_produced++;
|
|
|
+ if (waitqueue_active(&buf->read_wait)) {
|
|
|
+ PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf);
|
|
|
+ schedule_delayed_work(&buf->wake_readers, 1);
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ old = buf->data;
|
|
|
+ new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
|
|
|
+ new = buf->start + new_subbuf * buf->chan->subbuf_size;
|
|
|
+ buf->offset = 0;
|
|
|
+ if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
|
|
|
+ buf->offset = buf->chan->subbuf_size + 1;
|
|
|
+ return 0;
|
|
|
+ }
|
|
|
+ buf->data = new;
|
|
|
+ buf->padding[new_subbuf] = 0;
|
|
|
+
|
|
|
+ if (unlikely(length + buf->offset > buf->chan->subbuf_size))
|
|
|
+ goto toobig;
|
|
|
+
|
|
|
+ return length;
|
|
|
+
|
|
|
+toobig:
|
|
|
+ buf->chan->last_toobig = length;
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(relay_switch_subbuf);
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
|
|
|
+ * @chan: the channel
|
|
|
+ * @cpu: the cpu associated with the channel buffer to update
|
|
|
+ * @subbufs_consumed: number of sub-buffers to add to current buf's count
|
|
|
+ *
|
|
|
+ * Adds to the channel buffer's consumed sub-buffer count.
|
|
|
+ * subbufs_consumed should be the number of sub-buffers newly consumed,
|
|
|
+ * not the total consumed.
|
|
|
+ *
|
|
|
+ * NOTE: kernel clients don't need to call this function if the channel
|
|
|
+ * mode is 'overwrite'.
|
|
|
+ */
|
|
|
+void relay_subbufs_consumed(struct rchan *chan,
|
|
|
+ unsigned int cpu,
|
|
|
+ size_t subbufs_consumed)
|
|
|
+{
|
|
|
+ struct rchan_buf *buf;
|
|
|
+
|
|
|
+ if (!chan)
|
|
|
+ return;
|
|
|
+
|
|
|
+ if (cpu >= NR_CPUS || !chan->buf[cpu])
|
|
|
+ return;
|
|
|
+
|
|
|
+ buf = chan->buf[cpu];
|
|
|
+ buf->subbufs_consumed += subbufs_consumed;
|
|
|
+ if (buf->subbufs_consumed > buf->subbufs_produced)
|
|
|
+ buf->subbufs_consumed = buf->subbufs_produced;
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_close - close the channel
|
|
|
+ * @chan: the channel
|
|
|
+ *
|
|
|
+ * Closes all channel buffers and frees the channel.
|
|
|
+ */
|
|
|
+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] || chan->buf[i] == prev)
|
|
|
+ break;
|
|
|
+ relay_close_buf(chan->buf[i]);
|
|
|
+ prev = chan->buf[i];
|
|
|
+ }
|
|
|
+
|
|
|
+ if (chan->last_toobig)
|
|
|
+ printk(KERN_WARNING "relay: one or more items not logged "
|
|
|
+ "[item size (%Zd) > sub-buffer size (%Zd)]\n",
|
|
|
+ chan->last_toobig, chan->subbuf_size);
|
|
|
+
|
|
|
+ kref_put(&chan->kref, relay_destroy_channel);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(relay_close);
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_flush - close the channel
|
|
|
+ * @chan: the channel
|
|
|
+ *
|
|
|
+ * Flushes all channel buffers i.e. forces buffer switch.
|
|
|
+ */
|
|
|
+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] || chan->buf[i] == prev)
|
|
|
+ break;
|
|
|
+ relay_switch_subbuf(chan->buf[i], 0);
|
|
|
+ prev = chan->buf[i];
|
|
|
+ }
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(relay_flush);
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_open - open file op for relay files
|
|
|
+ * @inode: the inode
|
|
|
+ * @filp: the file
|
|
|
+ *
|
|
|
+ * Increments the channel buffer refcount.
|
|
|
+ */
|
|
|
+static int relay_file_open(struct inode *inode, struct file *filp)
|
|
|
+{
|
|
|
+ struct rchan_buf *buf = inode->u.generic_ip;
|
|
|
+ kref_get(&buf->kref);
|
|
|
+ filp->private_data = buf;
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_mmap - mmap file op for relay files
|
|
|
+ * @filp: the file
|
|
|
+ * @vma: the vma describing what to map
|
|
|
+ *
|
|
|
+ * Calls upon relay_mmap_buf to map the file into user space.
|
|
|
+ */
|
|
|
+static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
|
|
|
+{
|
|
|
+ struct rchan_buf *buf = filp->private_data;
|
|
|
+ return relay_mmap_buf(buf, vma);
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_poll - poll file op for relay files
|
|
|
+ * @filp: the file
|
|
|
+ * @wait: poll table
|
|
|
+ *
|
|
|
+ * Poll implemention.
|
|
|
+ */
|
|
|
+static unsigned int relay_file_poll(struct file *filp, poll_table *wait)
|
|
|
+{
|
|
|
+ unsigned int mask = 0;
|
|
|
+ struct rchan_buf *buf = filp->private_data;
|
|
|
+
|
|
|
+ if (buf->finalized)
|
|
|
+ return POLLERR;
|
|
|
+
|
|
|
+ if (filp->f_mode & FMODE_READ) {
|
|
|
+ poll_wait(filp, &buf->read_wait, wait);
|
|
|
+ if (!relay_buf_empty(buf))
|
|
|
+ mask |= POLLIN | POLLRDNORM;
|
|
|
+ }
|
|
|
+
|
|
|
+ return mask;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_release - release file op for relay files
|
|
|
+ * @inode: the inode
|
|
|
+ * @filp: the file
|
|
|
+ *
|
|
|
+ * Decrements the channel refcount, as the filesystem is
|
|
|
+ * no longer using it.
|
|
|
+ */
|
|
|
+static int relay_file_release(struct inode *inode, struct file *filp)
|
|
|
+{
|
|
|
+ struct rchan_buf *buf = filp->private_data;
|
|
|
+ kref_put(&buf->kref, relay_remove_buf);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_read_consume - update the consumed count for the buffer
|
|
|
+ */
|
|
|
+static void relay_file_read_consume(struct rchan_buf *buf,
|
|
|
+ size_t read_pos,
|
|
|
+ size_t bytes_consumed)
|
|
|
+{
|
|
|
+ size_t subbuf_size = buf->chan->subbuf_size;
|
|
|
+ size_t n_subbufs = buf->chan->n_subbufs;
|
|
|
+ size_t read_subbuf;
|
|
|
+
|
|
|
+ if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
|
|
|
+ relay_subbufs_consumed(buf->chan, buf->cpu, 1);
|
|
|
+ buf->bytes_consumed = 0;
|
|
|
+ }
|
|
|
+
|
|
|
+ buf->bytes_consumed += bytes_consumed;
|
|
|
+ read_subbuf = read_pos / buf->chan->subbuf_size;
|
|
|
+ if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
|
|
|
+ if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
|
|
|
+ (buf->offset == subbuf_size))
|
|
|
+ return;
|
|
|
+ relay_subbufs_consumed(buf->chan, buf->cpu, 1);
|
|
|
+ buf->bytes_consumed = 0;
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_read_avail - boolean, are there unconsumed bytes available?
|
|
|
+ */
|
|
|
+static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
|
|
|
+{
|
|
|
+ size_t bytes_produced, bytes_consumed, write_offset;
|
|
|
+ size_t subbuf_size = buf->chan->subbuf_size;
|
|
|
+ size_t n_subbufs = buf->chan->n_subbufs;
|
|
|
+ size_t produced = buf->subbufs_produced % n_subbufs;
|
|
|
+ size_t consumed = buf->subbufs_consumed % n_subbufs;
|
|
|
+
|
|
|
+ write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
|
|
|
+
|
|
|
+ if (consumed > produced) {
|
|
|
+ if ((produced > n_subbufs) &&
|
|
|
+ (produced + n_subbufs - consumed <= n_subbufs))
|
|
|
+ produced += n_subbufs;
|
|
|
+ } else if (consumed == produced) {
|
|
|
+ if (buf->offset > subbuf_size) {
|
|
|
+ produced += n_subbufs;
|
|
|
+ if (buf->subbufs_produced == buf->subbufs_consumed)
|
|
|
+ consumed += n_subbufs;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ if (buf->offset > subbuf_size)
|
|
|
+ bytes_produced = (produced - 1) * subbuf_size + write_offset;
|
|
|
+ else
|
|
|
+ bytes_produced = produced * subbuf_size + write_offset;
|
|
|
+ bytes_consumed = consumed * subbuf_size + buf->bytes_consumed;
|
|
|
+
|
|
|
+ if (bytes_produced == bytes_consumed)
|
|
|
+ return 0;
|
|
|
+
|
|
|
+ relay_file_read_consume(buf, read_pos, 0);
|
|
|
+
|
|
|
+ return 1;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_read_subbuf_avail - return bytes available in sub-buffer
|
|
|
+ */
|
|
|
+static size_t relay_file_read_subbuf_avail(size_t read_pos,
|
|
|
+ struct rchan_buf *buf)
|
|
|
+{
|
|
|
+ size_t padding, avail = 0;
|
|
|
+ size_t read_subbuf, read_offset, write_subbuf, write_offset;
|
|
|
+ size_t subbuf_size = buf->chan->subbuf_size;
|
|
|
+
|
|
|
+ write_subbuf = (buf->data - buf->start) / subbuf_size;
|
|
|
+ write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
|
|
|
+ read_subbuf = read_pos / subbuf_size;
|
|
|
+ read_offset = read_pos % subbuf_size;
|
|
|
+ padding = buf->padding[read_subbuf];
|
|
|
+
|
|
|
+ if (read_subbuf == write_subbuf) {
|
|
|
+ if (read_offset + padding < write_offset)
|
|
|
+ avail = write_offset - (read_offset + padding);
|
|
|
+ } else
|
|
|
+ avail = (subbuf_size - padding) - read_offset;
|
|
|
+
|
|
|
+ return avail;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_read_start_pos - find the first available byte to read
|
|
|
+ *
|
|
|
+ * If the read_pos is in the middle of padding, return the
|
|
|
+ * position of the first actually available byte, otherwise
|
|
|
+ * return the original value.
|
|
|
+ */
|
|
|
+static size_t relay_file_read_start_pos(size_t read_pos,
|
|
|
+ struct rchan_buf *buf)
|
|
|
+{
|
|
|
+ size_t read_subbuf, padding, padding_start, padding_end;
|
|
|
+ size_t subbuf_size = buf->chan->subbuf_size;
|
|
|
+ size_t n_subbufs = buf->chan->n_subbufs;
|
|
|
+
|
|
|
+ read_subbuf = read_pos / subbuf_size;
|
|
|
+ padding = buf->padding[read_subbuf];
|
|
|
+ padding_start = (read_subbuf + 1) * subbuf_size - padding;
|
|
|
+ padding_end = (read_subbuf + 1) * subbuf_size;
|
|
|
+ if (read_pos >= padding_start && read_pos < padding_end) {
|
|
|
+ read_subbuf = (read_subbuf + 1) % n_subbufs;
|
|
|
+ read_pos = read_subbuf * subbuf_size;
|
|
|
+ }
|
|
|
+
|
|
|
+ return read_pos;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_read_end_pos - return the new read position
|
|
|
+ */
|
|
|
+static size_t relay_file_read_end_pos(struct rchan_buf *buf,
|
|
|
+ size_t read_pos,
|
|
|
+ size_t count)
|
|
|
+{
|
|
|
+ size_t read_subbuf, padding, end_pos;
|
|
|
+ size_t subbuf_size = buf->chan->subbuf_size;
|
|
|
+ size_t n_subbufs = buf->chan->n_subbufs;
|
|
|
+
|
|
|
+ read_subbuf = read_pos / subbuf_size;
|
|
|
+ padding = buf->padding[read_subbuf];
|
|
|
+ if (read_pos % subbuf_size + count + padding == subbuf_size)
|
|
|
+ end_pos = (read_subbuf + 1) * subbuf_size;
|
|
|
+ else
|
|
|
+ end_pos = read_pos + count;
|
|
|
+ if (end_pos >= subbuf_size * n_subbufs)
|
|
|
+ end_pos = 0;
|
|
|
+
|
|
|
+ return end_pos;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * relay_file_read - read file op for relay files
|
|
|
+ * @filp: the file
|
|
|
+ * @buffer: the userspace buffer
|
|
|
+ * @count: number of bytes to read
|
|
|
+ * @ppos: position to read from
|
|
|
+ *
|
|
|
+ * Reads count bytes or the number of bytes available in the
|
|
|
+ * current sub-buffer being read, whichever is smaller.
|
|
|
+ */
|
|
|
+static ssize_t relay_file_read(struct file *filp,
|
|
|
+ char __user *buffer,
|
|
|
+ size_t count,
|
|
|
+ loff_t *ppos)
|
|
|
+{
|
|
|
+ struct rchan_buf *buf = filp->private_data;
|
|
|
+ struct inode *inode = filp->f_dentry->d_inode;
|
|
|
+ size_t read_start, avail;
|
|
|
+ ssize_t ret = 0;
|
|
|
+ void *from;
|
|
|
+
|
|
|
+ mutex_lock(&inode->i_mutex);
|
|
|
+ if(!relay_file_read_avail(buf, *ppos))
|
|
|
+ goto out;
|
|
|
+
|
|
|
+ read_start = relay_file_read_start_pos(*ppos, buf);
|
|
|
+ avail = relay_file_read_subbuf_avail(read_start, buf);
|
|
|
+ if (!avail)
|
|
|
+ goto out;
|
|
|
+
|
|
|
+ from = buf->start + read_start;
|
|
|
+ ret = count = min(count, avail);
|
|
|
+ if (copy_to_user(buffer, from, count)) {
|
|
|
+ ret = -EFAULT;
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+ relay_file_read_consume(buf, read_start, count);
|
|
|
+ *ppos = relay_file_read_end_pos(buf, read_start, count);
|
|
|
+out:
|
|
|
+ mutex_unlock(&inode->i_mutex);
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+struct file_operations relay_file_operations = {
|
|
|
+ .open = relay_file_open,
|
|
|
+ .poll = relay_file_poll,
|
|
|
+ .mmap = relay_file_mmap,
|
|
|
+ .read = relay_file_read,
|
|
|
+ .llseek = no_llseek,
|
|
|
+ .release = relay_file_release,
|
|
|
+};
|
|
|
+EXPORT_SYMBOL_GPL(relay_file_operations);
|
Jens Axboe