251 lines
5.2 KiB
C
251 lines
5.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* XDP user-space packet buffer
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* Copyright(c) 2018 Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/init.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/uaccess.h>
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#include <linux/slab.h>
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#include <linux/bpf.h>
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#include <linux/mm.h>
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#include "xdp_umem.h"
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#define XDP_UMEM_MIN_FRAME_SIZE 2048
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int xdp_umem_create(struct xdp_umem **umem)
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{
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*umem = kzalloc(sizeof(**umem), GFP_KERNEL);
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if (!(*umem))
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return -ENOMEM;
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return 0;
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}
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static void xdp_umem_unpin_pages(struct xdp_umem *umem)
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{
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unsigned int i;
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if (umem->pgs) {
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for (i = 0; i < umem->npgs; i++) {
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struct page *page = umem->pgs[i];
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set_page_dirty_lock(page);
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put_page(page);
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}
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kfree(umem->pgs);
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umem->pgs = NULL;
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}
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}
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static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
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{
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if (umem->user) {
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atomic_long_sub(umem->npgs, &umem->user->locked_vm);
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free_uid(umem->user);
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}
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}
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static void xdp_umem_release(struct xdp_umem *umem)
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{
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struct task_struct *task;
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struct mm_struct *mm;
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if (umem->fq) {
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xskq_destroy(umem->fq);
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umem->fq = NULL;
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}
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if (umem->pgs) {
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xdp_umem_unpin_pages(umem);
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task = get_pid_task(umem->pid, PIDTYPE_PID);
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put_pid(umem->pid);
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if (!task)
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goto out;
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mm = get_task_mm(task);
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put_task_struct(task);
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if (!mm)
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goto out;
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mmput(mm);
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umem->pgs = NULL;
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}
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xdp_umem_unaccount_pages(umem);
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out:
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kfree(umem);
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}
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static void xdp_umem_release_deferred(struct work_struct *work)
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{
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struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
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xdp_umem_release(umem);
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}
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void xdp_get_umem(struct xdp_umem *umem)
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{
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atomic_inc(&umem->users);
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}
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void xdp_put_umem(struct xdp_umem *umem)
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{
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if (!umem)
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return;
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if (atomic_dec_and_test(&umem->users)) {
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INIT_WORK(&umem->work, xdp_umem_release_deferred);
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schedule_work(&umem->work);
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}
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}
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static int xdp_umem_pin_pages(struct xdp_umem *umem)
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{
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unsigned int gup_flags = FOLL_WRITE;
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long npgs;
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int err;
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umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs), GFP_KERNEL);
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if (!umem->pgs)
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return -ENOMEM;
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down_write(¤t->mm->mmap_sem);
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npgs = get_user_pages(umem->address, umem->npgs,
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gup_flags, &umem->pgs[0], NULL);
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up_write(¤t->mm->mmap_sem);
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if (npgs != umem->npgs) {
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if (npgs >= 0) {
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umem->npgs = npgs;
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err = -ENOMEM;
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goto out_pin;
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}
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err = npgs;
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goto out_pgs;
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}
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return 0;
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out_pin:
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xdp_umem_unpin_pages(umem);
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out_pgs:
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kfree(umem->pgs);
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umem->pgs = NULL;
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return err;
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}
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static int xdp_umem_account_pages(struct xdp_umem *umem)
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{
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unsigned long lock_limit, new_npgs, old_npgs;
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if (capable(CAP_IPC_LOCK))
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return 0;
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lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
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umem->user = get_uid(current_user());
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do {
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old_npgs = atomic_long_read(&umem->user->locked_vm);
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new_npgs = old_npgs + umem->npgs;
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if (new_npgs > lock_limit) {
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free_uid(umem->user);
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umem->user = NULL;
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return -ENOBUFS;
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}
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} while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
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new_npgs) != old_npgs);
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return 0;
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}
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int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
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{
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u32 frame_size = mr->frame_size, frame_headroom = mr->frame_headroom;
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u64 addr = mr->addr, size = mr->len;
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unsigned int nframes, nfpp;
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int size_chk, err;
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if (!umem)
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return -EINVAL;
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if (frame_size < XDP_UMEM_MIN_FRAME_SIZE || frame_size > PAGE_SIZE) {
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/* Strictly speaking we could support this, if:
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* - huge pages, or*
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* - using an IOMMU, or
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* - making sure the memory area is consecutive
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* but for now, we simply say "computer says no".
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*/
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return -EINVAL;
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}
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if (!is_power_of_2(frame_size))
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return -EINVAL;
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if (!PAGE_ALIGNED(addr)) {
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/* Memory area has to be page size aligned. For
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* simplicity, this might change.
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*/
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return -EINVAL;
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}
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if ((addr + size) < addr)
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return -EINVAL;
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nframes = size / frame_size;
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if (nframes == 0 || nframes > UINT_MAX)
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return -EINVAL;
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nfpp = PAGE_SIZE / frame_size;
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if (nframes < nfpp || nframes % nfpp)
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return -EINVAL;
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frame_headroom = ALIGN(frame_headroom, 64);
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size_chk = frame_size - frame_headroom - XDP_PACKET_HEADROOM;
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if (size_chk < 0)
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return -EINVAL;
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umem->pid = get_task_pid(current, PIDTYPE_PID);
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umem->size = (size_t)size;
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umem->address = (unsigned long)addr;
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umem->props.frame_size = frame_size;
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umem->props.nframes = nframes;
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umem->frame_headroom = frame_headroom;
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umem->npgs = size / PAGE_SIZE;
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umem->pgs = NULL;
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umem->user = NULL;
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umem->frame_size_log2 = ilog2(frame_size);
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umem->nfpp_mask = nfpp - 1;
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umem->nfpplog2 = ilog2(nfpp);
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atomic_set(&umem->users, 1);
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err = xdp_umem_account_pages(umem);
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if (err)
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goto out;
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err = xdp_umem_pin_pages(umem);
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if (err)
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goto out_account;
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return 0;
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out_account:
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xdp_umem_unaccount_pages(umem);
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out:
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put_pid(umem->pid);
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return err;
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}
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