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io_uring/net: only import send_zc buffer once 

io_send_zc() guards its call to io_send_zc_import() with if (!done_io)
in an attempt to avoid calling it redundantly on the same req. However,
if the initial non-blocking issue returns -EAGAIN, done_io will stay 0.
This causes the subsequent issue to unnecessarily re-import the buffer.

Add an explicit flag "imported" to io_sr_msg to track if its buffer has
already been imported. Clear the flag in io_send_zc_prep(). Call
io_send_zc_import() and set the flag in io_send_zc() if it is unset.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 54cdcca05a ("io_uring/net: switch io_send() and io_send_zc() to using io_async_msghdr")
Link: https://lore.kernel.org/r/20250321184819.3847386-2-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
pull/1188/head
Caleb Sander Mateos 2025-03-21 12:48:17 -06:00 committed by Jens Axboe
parent ef49027529
commit 8e3100fcc5
1 changed files with 4 additions and 1 deletions
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5
io_uring/net.c
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@ -77,6 +77,7 @@ struct io_sr_msg {
/* initialised and used only by !msg send variants */
u16 buf_group;
bool retry;
bool imported; /* only for io_send_zc */
void __user *msg_control;
/* used only for send zerocopy */
struct io_kiocb *notif;
@ -1306,6 +1307,7 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
zc->done_io = 0;
zc->retry = false;
zc->imported = false;
req->flags |= REQ_F_POLL_NO_LAZY;
if (unlikely(READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3)))
@ -1451,7 +1453,8 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
(zc->flags & IORING_RECVSEND_POLL_FIRST))
return -EAGAIN;
if (!zc->done_io) {
if (!zc->imported) {
zc->imported = true;
ret = io_send_zc_import(req, issue_flags);
if (unlikely(ret))
return ret;