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M . Jones" , Ilya Dryomov , Peter Lieven , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Fam Zheng , Ronnie Sahlberg Subject: [PATCH 16/16] win32-aio: Run CB in original context Date: Tue, 28 Oct 2025 17:33:42 +0100 Message-ID: <20251028163343.116249-17-hreitz@redhat.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251028163343.116249-1-hreitz@redhat.com> References: <20251028163343.116249-1-hreitz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1761669488008158500 AIO callbacks must be called in the originally calling AioContext, regardless of the BDS=E2=80=99s =E2=80=9Cmain=E2=80=9D AioContext. Note: I tried to test this (under wine), but failed. Whenever I tried to use multiqueue or even just an I/O thread for a virtio-blk (or virtio-scsi) device, I/O stalled, both with and without this patch. For what it=E2=80=99s worth, when not using an I/O thread, I/O continued to= work with this patch. Signed-off-by: Hanna Czenczek --- block/win32-aio.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/block/win32-aio.c b/block/win32-aio.c index 6327861e1d..f0689f3ee9 100644 --- a/block/win32-aio.c +++ b/block/win32-aio.c @@ -48,48 +48,62 @@ struct QEMUWin32AIOState { typedef struct QEMUWin32AIOCB { BlockAIOCB common; struct QEMUWin32AIOState *ctx; + AioContext *req_ctx; int nbytes; OVERLAPPED ov; QEMUIOVector *qiov; void *buf; bool is_read; bool is_linear; + int ret; } QEMUWin32AIOCB; =20 +static void win32_aio_completion_cb_bh(void *opaque) +{ + QEMUWin32AIOCB *waiocb =3D opaque; + + waiocb->common.cb(waiocb->common.opaque, waiocb->ret); + aio_context_unref(waiocb->req_ctx); + qemu_aio_unref(waiocb); +} + /* * Completes an AIO request (calls the callback and frees the ACB). */ static void win32_aio_process_completion(QEMUWin32AIOState *s, QEMUWin32AIOCB *waiocb, DWORD count) { - int ret; s->count--; =20 if (waiocb->ov.Internal !=3D 0) { - ret =3D -EIO; + waiocb->ret =3D -EIO; } else { - ret =3D 0; + waiocb->ret =3D 0; if (count < waiocb->nbytes) { /* Short reads mean EOF, pad with zeros. */ if (waiocb->is_read) { qemu_iovec_memset(waiocb->qiov, count, 0, waiocb->qiov->size - count); } else { - ret =3D -EINVAL; + waiocb->ret =3D -EINVAL; } } } =20 if (!waiocb->is_linear) { - if (ret =3D=3D 0 && waiocb->is_read) { + if (waiocb->ret =3D=3D 0 && waiocb->is_read) { QEMUIOVector *qiov =3D waiocb->qiov; iov_from_buf(qiov->iov, qiov->niov, 0, waiocb->buf, qiov->size= ); } qemu_vfree(waiocb->buf); } =20 - waiocb->common.cb(waiocb->common.opaque, ret); - qemu_aio_unref(waiocb); + if (waiocb->req_ctx =3D=3D s->aio_ctx) { + win32_aio_completion_cb_bh(waiocb); + } else { + aio_bh_schedule_oneshot(waiocb->req_ctx, win32_aio_completion_cb_b= h, + waiocb); + } } =20 static void win32_aio_completion_cb(EventNotifier *e) @@ -120,10 +134,13 @@ BlockAIOCB *win32_aio_submit(BlockDriverState *bs, DWORD rc; =20 waiocb =3D qemu_aio_get(&win32_aiocb_info, bs, cb, opaque); + waiocb->req_ctx =3D qemu_get_current_aio_context(); waiocb->nbytes =3D bytes; waiocb->qiov =3D qiov; waiocb->is_read =3D (type =3D=3D QEMU_AIO_READ); =20 + aio_context_ref(waiocb->req_ctx); + if (qiov->niov > 1) { waiocb->buf =3D qemu_try_blockalign(bs, qiov->size); if (waiocb->buf =3D=3D NULL) { --=20 2.51.0