提交 4e24db5b 编写于 作者: L Linus Torvalds

Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  lguest: update comments to reflect LHCALL_LOAD_GDT_ENTRY.
  virtio: console: Prevent userspace from submitting NULL buffers
  virtio: console: Fix poll blocking even though there is data to read
......@@ -324,9 +324,8 @@ static void lguest_load_gdt(const struct desc_ptr *desc)
}
/*
* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
* then tell the Host to reload the entire thing. This operation is so rare
* that this naive implementation is reasonable.
* For a single GDT entry which changes, we simply change our copy and
* then tell the host about it.
*/
static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
const void *desc, int type)
......@@ -338,9 +337,13 @@ static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
}
/*
* OK, I lied. There are three "thread local storage" GDT entries which change
* There are three "thread local storage" GDT entries which change
* on every context switch (these three entries are how glibc implements
* __thread variables). So we have a hypercall specifically for this case.
* __thread variables). As an optimization, we have a hypercall
* specifically for this case.
*
* Wouldn't it be nicer to have a general LOAD_GDT_ENTRIES hypercall
* which took a range of entries?
*/
static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
{
......
......@@ -596,6 +596,10 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
ssize_t ret;
bool nonblock;
/* Userspace could be out to fool us */
if (!count)
return 0;
port = filp->private_data;
nonblock = filp->f_flags & O_NONBLOCK;
......@@ -642,7 +646,7 @@ static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
poll_wait(filp, &port->waitqueue, wait);
ret = 0;
if (port->inbuf)
if (!will_read_block(port))
ret |= POLLIN | POLLRDNORM;
if (!will_write_block(port))
ret |= POLLOUT;
......
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