[PATCH v3 25/28] assorted variants of irqfd setup: convert to CLASS(fd)

Al Viro
2024-11-02T05:08:32Z

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>
---
drivers/vfio/virqfd.c | 16 +++-------------
drivers/virt/acrn/irqfd.c | 13 ++++---------
drivers/xen/privcmd.c | 17 ++++-------------
virt/kvm/eventfd.c | 15 +++------------
4 files changed, 14 insertions(+), 47 deletions(-)

diff --git a/drivers/vfio/virqfd.c b/drivers/vfio/virqfd.c
index d22881245e89..aa2891f97508 100644
--- a/drivers/vfio/virqfd.c
+++ b/drivers/vfio/virqfd.c
@@ -113,7 +113,6 @@ int vfio_virqfd_enable(void *opaque,
void (*thread)(void *, void *),
void *data, struct virqfd **pvirqfd, int fd)
{
- struct fd irqfd;
struct eventfd_ctx *ctx;
struct virqfd *virqfd;
int ret = 0;
@@ -133,8 +132,8 @@ int vfio_virqfd_enable(void *opaque,
INIT_WORK(&virqfd->inject, virqfd_inject);
INIT_WORK(&virqfd->flush_inject, virqfd_flush_inject);

- irqfd = fdget(fd);
- if (!fd_file(irqfd)) {
+ CLASS(fd, irqfd)(fd);
+ if (fd_empty(irqfd)) {
ret = -EBADF;
goto err_fd;
}
@@ -142,7 +141,7 @@ int vfio_virqfd_enable(void *opaque,
ctx = eventfd_ctx_fileget(fd_file(irqfd));
if (IS_ERR(ctx)) {
ret = PTR_ERR(ctx);
- goto err_ctx;
+ goto err_fd;
}

virqfd->eventfd = ctx;
@@ -181,18 +180,9 @@ int vfio_virqfd_enable(void *opaque,
if ((!handler || handler(opaque, data)) && thread)
schedule_work(&virqfd->inject);
}
-
- /*
- * Do not drop the file until the irqfd is fully initialized,
- * otherwise we might race against the EPOLLHUP.
- */
- fdput(irqfd);
-
return 0;
err_busy:
eventfd_ctx_put(ctx);
-err_ctx:
- fdput(irqfd);
err_fd:
kfree(virqfd);

diff --git a/drivers/virt/acrn/irqfd.c b/drivers/virt/acrn/irqfd.c
index 9994d818bb7e..b7da24ca1475 100644
--- a/drivers/virt/acrn/irqfd.c
+++ b/drivers/virt/acrn/irqfd.c
@@ -112,7 +112,6 @@ static int acrn_irqfd_assign(struct acrn_vm *vm, struct acrn_irqfd *args)
struct eventfd_ctx *eventfd = NULL;
struct hsm_irqfd *irqfd, *tmp;
__poll_t events;
- struct fd f;
int ret = 0;

irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
@@ -124,8 +123,8 @@ static int acrn_irqfd_assign(struct acrn_vm *vm, struct acrn_irqfd *args)
INIT_LIST_HEAD(&irqfd->list);
INIT_WORK(&irqfd->shutdown, hsm_irqfd_shutdown_work);

- f = fdget(args->fd);
- if (!fd_file(f)) {
+ CLASS(fd, f)(args->fd);
+ if (fd_empty(f)) {
ret = -EBADF;
goto out;
}
@@ -133,7 +132,7 @@ static int acrn_irqfd_assign(struct acrn_vm *vm, struct acrn_irqfd *args)
eventfd = eventfd_ctx_fileget(fd_file(f));
if (IS_ERR(eventfd)) {
ret = PTR_ERR(eventfd);
- goto fail;
+ goto out;
}

irqfd->eventfd = eventfd;
@@ -162,13 +161,9 @@ static int acrn_irqfd_assign(struct acrn_vm *vm, struct acrn_irqfd *args)
if (events & EPOLLIN)
acrn_irqfd_inject(irqfd);

- fdput(f);
return 0;
fail:
- if (eventfd && !IS_ERR(eventfd))
- eventfd_ctx_put(eventfd);
-
- fdput(f);
+ eventfd_ctx_put(eventfd);
out:
kfree(irqfd);
return ret;
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 79070494070d..0ca532614343 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -967,10 +967,11 @@ static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
struct privcmd_kernel_irqfd *kirqfd, *tmp;
unsigned long flags;
__poll_t events;
- struct fd f;
void *dm_op;
int ret, idx;

+ CLASS(fd, f)(irqfd->fd);
+
kirqfd = kzalloc(sizeof(*kirqfd) + irqfd->size, GFP_KERNEL);
if (!kirqfd)
return -ENOMEM;
@@ -986,8 +987,7 @@ static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
kirqfd->dom = irqfd->dom;
INIT_WORK(&kirqfd->shutdown, irqfd_shutdown);

- f = fdget(irqfd->fd);
- if (!fd_file(f)) {
+ if (fd_empty(f)) {
ret = -EBADF;
goto error_kfree;
}
@@ -995,7 +995,7 @@ static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
kirqfd->eventfd = eventfd_ctx_fileget(fd_file(f));
if (IS_ERR(kirqfd->eventfd)) {
ret = PTR_ERR(kirqfd->eventfd);
- goto error_fd_put;
+ goto error_kfree;
}

/*
@@ -1028,20 +1028,11 @@ static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
irqfd_inject(kirqfd);

srcu_read_unlock(&irqfds_srcu, idx);
-
- /*
- * Do not drop the file until the kirqfd is fully initialized, otherwise
- * we might race against the EPOLLHUP.
- */
- fdput(f);
return 0;

error_eventfd:
eventfd_ctx_put(kirqfd->eventfd);

-error_fd_put:
- fdput(f);
-
error_kfree:
kfree(kirqfd);
return ret;
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 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
if (eventfd && !IS_ERR(eventfd))
eventfd_ctx_put(eventfd);

- fdput(f);
-
out:
kfree(irqfd);
return ret;
--
2.39.5