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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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3a6ee45e3c
commit e307e66981 upstream.
It might be useful for applications to detect if a zero copy transfer with
SEND[MSG]_ZC was actually possible or not. The application can fallback to
plain SEND[MSG] in order to avoid the overhead of two cqes per request. Or
it can generate a log message that could indicate to an administrator that
no zero copy was possible and could explain degraded performance.
Cc: stable@vger.kernel.org # 6.1
Link: https://lore.kernel.org/io-uring/fb6a7599-8a9b-15e5-9b64-6cd9d01c6ff4@gmail.com/T/#m2b0d9df94ce43b0e69e6c089bdff0ce6babbdfaa
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8945b01756d902f5d5b0667f20b957ad3f742e5e.1666895626.git.metze@samba.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
85 lines
2.1 KiB
C
85 lines
2.1 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 void __io_notif_complete_tw(struct io_kiocb *notif, bool *locked)
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{
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struct io_notif_data *nd = io_notif_to_data(notif);
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struct io_ring_ctx *ctx = notif->ctx;
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if (nd->account_pages && ctx->user) {
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__io_unaccount_mem(ctx->user, nd->account_pages);
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nd->account_pages = 0;
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}
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if (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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io_req_task_complete(notif, locked);
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}
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static void io_uring_tx_zerocopy_callback(struct sk_buff *skb,
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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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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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notif->io_task_work.func = __io_notif_complete_tw;
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io_req_task_work_add(notif);
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}
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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_refill(ctx)))
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return NULL;
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notif = io_alloc_req(ctx);
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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->task = current;
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io_get_task_refs(1);
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notif->rsrc_node = NULL;
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io_req_set_rsrc_node(notif, ctx, 0);
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nd = io_notif_to_data(notif);
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nd->account_pages = 0;
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nd->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
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nd->uarg.callback = io_uring_tx_zerocopy_callback;
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nd->zc_report = nd->zc_used = nd->zc_copied = false;
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refcount_set(&nd->uarg.refcnt, 1);
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return notif;
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}
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void io_notif_flush(struct io_kiocb *notif)
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__must_hold(&slot->notif->ctx->uring_lock)
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{
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struct io_notif_data *nd = io_notif_to_data(notif);
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/* drop slot's master ref */
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if (refcount_dec_and_test(&nd->uarg.refcnt)) {
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notif->io_task_work.func = __io_notif_complete_tw;
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io_req_task_work_add(notif);
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}
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}
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