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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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b6f58a3f4a
Rather than store the task_struct itself in struct io_kiocb, store the io_uring specific task_struct. The life times are the same in terms of io_uring, and this avoids doing some dereferences through the task_struct. For the hot path of putting local task references, we can deref req->tctx instead, which we'll need anyway in that function regardless of whether it's local or remote references. This is mostly straight forward, except the original task PF_EXITING check needs a bit of tweaking. task_work is _always_ run from the originating task, except in the fallback case, where it's run from a kernel thread. Replace the potentially racy (in case of fallback work) checks for req->task->flags with current->flags. It's either the still the original task, in which case PF_EXITING will be sane, or it has PF_KTHREAD set, in which case it's fallback work. Both cases should prevent moving forward with the given request. Signed-off-by: Jens Axboe <axboe@kernel.dk>
134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/file.h>
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#include <linux/slab.h>
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#include <linux/net.h>
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#include <linux/io_uring.h>
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#include "io_uring.h"
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#include "notif.h"
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#include "rsrc.h"
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static const struct ubuf_info_ops io_ubuf_ops;
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static void io_notif_tw_complete(struct io_kiocb *notif, struct io_tw_state *ts)
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{
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struct io_notif_data *nd = io_notif_to_data(notif);
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do {
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notif = cmd_to_io_kiocb(nd);
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lockdep_assert(refcount_read(&nd->uarg.refcnt) == 0);
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if (unlikely(nd->zc_report) && (nd->zc_copied || !nd->zc_used))
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notif->cqe.res |= IORING_NOTIF_USAGE_ZC_COPIED;
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if (nd->account_pages && notif->ctx->user) {
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__io_unaccount_mem(notif->ctx->user, nd->account_pages);
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nd->account_pages = 0;
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}
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nd = nd->next;
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io_req_task_complete(notif, ts);
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} while (nd);
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}
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void io_tx_ubuf_complete(struct sk_buff *skb, struct ubuf_info *uarg,
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bool success)
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{
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struct io_notif_data *nd = container_of(uarg, struct io_notif_data, uarg);
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struct io_kiocb *notif = cmd_to_io_kiocb(nd);
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unsigned tw_flags;
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if (nd->zc_report) {
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if (success && !nd->zc_used && skb)
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WRITE_ONCE(nd->zc_used, true);
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else if (!success && !nd->zc_copied)
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WRITE_ONCE(nd->zc_copied, true);
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}
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if (!refcount_dec_and_test(&uarg->refcnt))
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return;
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if (nd->head != nd) {
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io_tx_ubuf_complete(skb, &nd->head->uarg, success);
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return;
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}
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tw_flags = nd->next ? 0 : IOU_F_TWQ_LAZY_WAKE;
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notif->io_task_work.func = io_notif_tw_complete;
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__io_req_task_work_add(notif, tw_flags);
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}
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static int io_link_skb(struct sk_buff *skb, struct ubuf_info *uarg)
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{
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struct io_notif_data *nd, *prev_nd;
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struct io_kiocb *prev_notif, *notif;
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struct ubuf_info *prev_uarg = skb_zcopy(skb);
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nd = container_of(uarg, struct io_notif_data, uarg);
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notif = cmd_to_io_kiocb(nd);
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if (!prev_uarg) {
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net_zcopy_get(&nd->uarg);
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skb_zcopy_init(skb, &nd->uarg);
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return 0;
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}
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/* handle it separately as we can't link a notif to itself */
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if (unlikely(prev_uarg == &nd->uarg))
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return 0;
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/* we can't join two links together, just request a fresh skb */
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if (unlikely(nd->head != nd || nd->next))
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return -EEXIST;
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/* don't mix zc providers */
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if (unlikely(prev_uarg->ops != &io_ubuf_ops))
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return -EEXIST;
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prev_nd = container_of(prev_uarg, struct io_notif_data, uarg);
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prev_notif = cmd_to_io_kiocb(nd);
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/* make sure all noifications can be finished in the same task_work */
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if (unlikely(notif->ctx != prev_notif->ctx ||
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notif->tctx != prev_notif->tctx))
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return -EEXIST;
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nd->head = prev_nd->head;
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nd->next = prev_nd->next;
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prev_nd->next = nd;
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net_zcopy_get(&nd->head->uarg);
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return 0;
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}
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static const struct ubuf_info_ops io_ubuf_ops = {
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.complete = io_tx_ubuf_complete,
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.link_skb = io_link_skb,
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};
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struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
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__must_hold(&ctx->uring_lock)
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{
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struct io_kiocb *notif;
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struct io_notif_data *nd;
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if (unlikely(!io_alloc_req(ctx, ¬if)))
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return NULL;
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notif->opcode = IORING_OP_NOP;
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notif->flags = 0;
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notif->file = NULL;
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notif->tctx = current->io_uring;
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io_get_task_refs(1);
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notif->file_node = NULL;
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notif->buf_node = NULL;
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nd = io_notif_to_data(notif);
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nd->zc_report = false;
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nd->account_pages = 0;
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nd->next = NULL;
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nd->head = nd;
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nd->uarg.flags = IO_NOTIF_UBUF_FLAGS;
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nd->uarg.ops = &io_ubuf_ops;
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refcount_set(&nd->uarg.refcnt, 1);
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return notif;
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}
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