* Copyright (C) 2011 Google, Inc.
* Copyright (C) 2012 Intel, Inc.
* Copyright (C) 2013 Intel, Inc.
+ * Copyright (C) 2014 Linaro Limited
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/goldfish.h>
+#include <linux/mm.h>
/*
* IMPORTANT: The following constants must match the ones used and defined
return 0;
}
-/* This function is used for both reading from and writing to a given
- * pipe.
- */
static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer,
- size_t bufflen, int is_write)
+ size_t bufflen, int is_write)
{
unsigned long irq_flags;
struct goldfish_pipe *pipe = filp->private_data;
struct goldfish_pipe_dev *dev = pipe->dev;
unsigned long address, address_end;
- int ret = 0;
+ int count = 0, ret = -EINVAL;
/* If the emulator already closed the pipe, no need to go further */
if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
address_end = address + bufflen;
while (address < address_end) {
- unsigned long page_end = (address & PAGE_MASK) + PAGE_SIZE;
- unsigned long next = page_end < address_end ? page_end
- : address_end;
- unsigned long avail = next - address;
+ unsigned long page_end = (address & PAGE_MASK) + PAGE_SIZE;
+ unsigned long next = page_end < address_end ? page_end
+ : address_end;
+ unsigned long avail = next - address;
int status, wakeBit;
-
- /* Ensure that the corresponding page is properly mapped */
- /* FIXME: this isn't safe or sufficient - use get_user_pages */
- if (is_write) {
- char c;
- /* Ensure that the page is mapped and readable */
- if (__get_user(c, (char __user *)address)) {
- if (!ret)
- ret = -EFAULT;
- break;
- }
- } else {
- /* Ensure that the page is mapped and writable */
- if (__put_user(0, (char __user *)address)) {
- if (!ret)
- ret = -EFAULT;
- break;
- }
- }
+ struct page *page;
+
+ /*
+ * We grab the pages on a page-by-page basis in case user
+ * space gives us a potentially huge buffer but the read only
+ * returns a small amount, then there's no need to pin that
+ * much memory to the process.
+ */
+ ret = get_user_pages(current, current->mm, address, 1,
+ !is_write, 0, &page, NULL);
+ if (ret < 0)
+ return ret;
/* Now, try to transfer the bytes in the current page */
spin_lock_irqsave(&dev->lock, irq_flags);
}
spin_unlock_irqrestore(&dev->lock, irq_flags);
+ if (status > 0 && !is_write)
+ set_page_dirty(page);
+ put_page(page);
+
if (status > 0) { /* Correct transfer */
- ret += status;
+ count += status;
address += status;
continue;
- }
-
- if (status == 0) /* EOF */
+ } else if (status == 0) { /* EOF */
+ ret = 0;
break;
-
- /* An error occured. If we already transfered stuff, just
- * return with its count. We expect the next call to return
- * an error code */
- if (ret > 0)
+ } else if (status < 0 && count > 0) {
+ /*
+ * An error occurred and we already transferred
+ * something on one of the previous pages.
+ * Just return what we already copied and log this
+ * err.
+ *
+ * Note: This seems like an incorrect approach but
+ * cannot change it until we check if any user space
+ * ABI relies on this behavior.
+ */
+ pr_info_ratelimited("android_pipe: backend returned error %d on %s\n",
+ status, is_write ? "write" : "read");
+ ret = 0;
break;
+ }
- /* If the error is not PIPE_ERROR_AGAIN, or if we are not in
- * non-blocking mode, just return the error code.
- */
+ /*
+ * If the error is not PIPE_ERROR_AGAIN, or if we are not in
+ * non-blocking mode, just return the error code.
+ */
if (status != PIPE_ERROR_AGAIN ||
(filp->f_flags & O_NONBLOCK) != 0) {
ret = goldfish_pipe_error_convert(status);
break;
}
- /* We will have to wait until more data/space is available.
- * First, mark the pipe as waiting for a specific wake signal.
- */
+ /*
+ * The backend blocked the read/write, wait until the backend
+ * tells us it's ready to process more data.
+ */
wakeBit = is_write ? BIT_WAKE_ON_WRITE : BIT_WAKE_ON_READ;
set_bit(wakeBit, &pipe->flags);
while (test_bit(wakeBit, &pipe->flags)) {
if (wait_event_interruptible(
pipe->wake_queue,
- !test_bit(wakeBit, &pipe->flags)))
- return -ERESTARTSYS;
+ !test_bit(wakeBit, &pipe->flags))) {
+ ret = -ERESTARTSYS;
+ break;
+ }
- if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
- return -EIO;
+ if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)) {
+ ret = -EIO;
+ break;
+ }
}
/* Try to re-acquire the lock */
- if (mutex_lock_interruptible(&pipe->lock))
- return -ERESTARTSYS;
-
- /* Try the transfer again */
- continue;
+ if (mutex_lock_interruptible(&pipe->lock)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
}
mutex_unlock(&pipe->lock);
- return ret;
+
+ if (ret < 0)
+ return ret;
+ else
+ return count;
}
static ssize_t goldfish_pipe_read(struct file *filp, char __user *buffer,
unsigned long irq_flags;
int count = 0;
- /* We're going to read from the emulator a list of (channel,flags)
- * pairs corresponding to the wake events that occured on each
- * blocked pipe (i.e. channel).
- */
+ /*
+ * We're going to read from the emulator a list of (channel,flags)
+ * pairs corresponding to the wake events that occurred on each
+ * blocked pipe (i.e. channel).
+ */
spin_lock_irqsave(&dev->lock, irq_flags);
for (;;) {
/* First read the channel, 0 means the end of the list */
projects / linux-2.6-microblaze.git / commitdiff