>>> On 1/13/2010 at 11:58 AM, in message <20100113165809.GA13334@xxxxxxxxxx>,
"Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
> Looks like repeatedly binding same fd to multiple gsi's with irqfd can
> use up a ton of kernel memory for irqfd structures.
>
> A simple fix is to allow each fd to only trigger one gsi: triggering a
> srorm of interrupts in guest is likely useless anyway, and we can do it
> by binding a single gsi to many interrupts if we really want to.
>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Seems reasonable to me.
Acked-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
> ---
>
> This patch is IMO a good candidate for 2.6.33 and 2.6.32.x.
>
> virt/kvm/eventfd.c | 15 +++++++++++++--
> 1 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> index 30f70fd..62e4cd9 100644
> --- a/virt/kvm/eventfd.c
> +++ b/virt/kvm/eventfd.c
> @@ -166,7 +166,7 @@ irqfd_ptable_queue_proc(struct file *file,
> wait_queue_head_t *wqh,
> static int
> kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
> {
> - struct _irqfd *irqfd;
> + struct _irqfd *irqfd, *tmp;
> struct file *file = NULL;
> struct eventfd_ctx *eventfd = NULL;
> int ret;
> @@ -203,9 +203,20 @@ kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
> init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
> init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
>
> + spin_lock_irq(&kvm->irqfds.lock);
> +
> + ret = 0;
> + list_for_each_entry(tmp, &kvm->irqfds.items, list) {
> + if (irqfd->eventfd != tmp->eventfd)
> + continue;
> + /* This fd is used for another irq already. */
> + ret = -EBUSY;
> + spin_unlock_irq(&kvm->irqfds.lock);
> + goto fail;
> + }
> +
> events = file->f_op->poll(file, &irqfd->pt);
>
> - spin_lock_irq(&kvm->irqfds.lock);
> list_add_tail(&irqfd->list, &kvm->irqfds.items);
> spin_unlock_irq(&kvm->irqfds.lock);
>
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