assorted variants of irqfd setup: convert to CLASS(fd)

in all of those failure exits prior to fdget() are plain returns and
the only thing done after fdput() is (on failure exits) a kfree(),
which can be done before fdput() just fine.

NOTE: in acrn_irqfd_assign() 'fail:' failure exit is wrong for
eventfd_ctx_fileget() failure (we only want fdput() there) and once
we stop doing that, it doesn't need to check if eventfd is NULL or
ERR_PTR(...) there.

NOTE: in privcmd we move fdget() up before the allocation - more
to the point, before the copy_from_user() attempt.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 12 deletions

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 6b390b622b72..249ba5b72e9b 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -304,7 +304,6 @@ static int
 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 {
 	struct kvm_kernel_irqfd *irqfd, *tmp;
-	struct fd f;
 	struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
 	int ret;
 	__poll_t events;
@@ -327,8 +326,8 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
 	seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
 
-	f = fdget(args->fd);
-	if (!fd_file(f)) {
+	CLASS(fd, f)(args->fd);
+	if (fd_empty(f)) {
 		ret = -EBADF;
 		goto out;
 	}
@@ -336,7 +335,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 	eventfd = eventfd_ctx_fileget(fd_file(f));
 	if (IS_ERR(eventfd)) {
 		ret = PTR_ERR(eventfd);
-		goto fail;
+		goto out;
 	}
 
 	irqfd->eventfd = eventfd;
@@ -440,12 +439,6 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 #endif
 
 	srcu_read_unlock(&kvm->irq_srcu, idx);
-
-	/*
-	 * do not drop the file until the irqfd is fully initialized, otherwise
-	 * we might race against the EPOLLHUP
-	 */
-	fdput(f);
 	return 0;
 
 fail:
@@ -458,8 +451,6 @@ fail:
 	if (eventfd && !IS_ERR(eventfd))
 		eventfd_ctx_put(eventfd);
 
-	fdput(f);
-
 out:
 	kfree(irqfd);
 	return ret;