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xsk: simplified umem setup

Browse source 
As suggested by Daniel Borkmann, the umem setup code was a too
defensive and complex. Here, we reduce the number of checks. Also, the
memory pinning is now folded into the umem creation, and we do correct
locking.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Björn Töpel 2018-05-22 09:35:02 +02:00 committed by Daniel Borkmann
parent 37b076933a
commit a49049ea25
3 changed files with 52 additions and 56 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

79
net/xdp/xdp_umem.c
View file

@ -16,39 +16,25 @@
#define XDP_UMEM_MIN_FRAME_SIZE 2048
int xdp_umem_create(struct xdp_umem **umem)
{
*umem = kzalloc(sizeof(**umem), GFP_KERNEL);
if (!*umem)
return -ENOMEM;
return 0;
}
static void xdp_umem_unpin_pages(struct xdp_umem *umem)
{
unsigned int i;
if (umem->pgs) {
for (i = 0; i < umem->npgs; i++) {
struct page *page = umem->pgs[i];
for (i = 0; i < umem->npgs; i++) {
struct page *page = umem->pgs[i];
set_page_dirty_lock(page);
put_page(page);
}
kfree(umem->pgs);
umem->pgs = NULL;
set_page_dirty_lock(page);
put_page(page);
}
kfree(umem->pgs);
umem->pgs = NULL;
}
static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
{
if (umem->user) {
atomic_long_sub(umem->npgs, &umem->user->locked_vm);
free_uid(umem->user);
}
atomic_long_sub(umem->npgs, &umem->user->locked_vm);
free_uid(umem->user);
}
static void xdp_umem_release(struct xdp_umem *umem)
@ -66,22 +52,18 @@ static void xdp_umem_release(struct xdp_umem *umem)
umem->cq = NULL;
}
if (umem->pgs) {
xdp_umem_unpin_pages(umem);
xdp_umem_unpin_pages(umem);
task = get_pid_task(umem->pid, PIDTYPE_PID);
put_pid(umem->pid);
if (!task)
goto out;
mm = get_task_mm(task);
put_task_struct(task);
if (!mm)
goto out;
mmput(mm);
umem->pgs = NULL;
}
task = get_pid_task(umem->pid, PIDTYPE_PID);
put_pid(umem->pid);
if (!task)
goto out;
mm = get_task_mm(task);
put_task_struct(task);
if (!mm)
goto out;
mmput(mm);
xdp_umem_unaccount_pages(umem);
out:
kfree(umem);
@ -167,16 +149,13 @@ static int xdp_umem_account_pages(struct xdp_umem *umem)
return 0;
}
int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
{
u32 frame_size = mr->frame_size, frame_headroom = mr->frame_headroom;
u64 addr = mr->addr, size = mr->len;
unsigned int nframes, nfpp;
int size_chk, err;
if (!umem)
return -EINVAL;
if (frame_size < XDP_UMEM_MIN_FRAME_SIZE || frame_size > PAGE_SIZE) {
/* Strictly speaking we could support this, if:
* - huge pages, or*
@ -245,6 +224,24 @@ int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
return err;
}
struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
{
struct xdp_umem *umem;
int err;
umem = kzalloc(sizeof(*umem), GFP_KERNEL);
if (!umem)
return ERR_PTR(-ENOMEM);
err = xdp_umem_reg(umem, mr);
if (err) {
kfree(umem);
return ERR_PTR(err);
}
return umem;
}
bool xdp_umem_validate_queues(struct xdp_umem *umem)
{
return umem->fq && umem->cq;

3
net/xdp/xdp_umem.h
View file

@ -50,9 +50,8 @@ static inline char *xdp_umem_get_data_with_headroom(struct xdp_umem *umem,
}
bool xdp_umem_validate_queues(struct xdp_umem *umem);
int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr);
void xdp_get_umem(struct xdp_umem *umem);
void xdp_put_umem(struct xdp_umem *umem);
int xdp_umem_create(struct xdp_umem **umem);
struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr);
#endif /* XDP_UMEM_H_ */

26
net/xdp/xsk.c
View file

@ -406,25 +406,23 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
struct xdp_umem_reg mr;
struct xdp_umem *umem;
if (xs->umem)
return -EBUSY;
if (copy_from_user(&mr, optval, sizeof(mr)))
return -EFAULT;
mutex_lock(&xs->mutex);
err = xdp_umem_create(&umem);
err = xdp_umem_reg(umem, &mr);
if (err) {
kfree(umem);
if (xs->umem) {
mutex_unlock(&xs->mutex);
return err;
return -EBUSY;
}
umem = xdp_umem_create(&mr);
if (IS_ERR(umem)) {
mutex_unlock(&xs->mutex);
return PTR_ERR(umem);
}
/* Make sure umem is ready before it can be seen by others */
smp_wmb();
xs->umem = umem;
mutex_unlock(&xs->mutex);
return 0;
@ -435,13 +433,15 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
struct xsk_queue **q;
int entries;
if (!xs->umem)
return -EINVAL;
if (copy_from_user(&entries, optval, sizeof(entries)))
return -EFAULT;
mutex_lock(&xs->mutex);
if (!xs->umem) {
mutex_unlock(&xs->mutex);
return -EINVAL;
}
q = (optname == XDP_UMEM_FILL_RING) ? &xs->umem->fq :
&xs->umem->cq;
err = xsk_init_queue(entries, q, true);