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Wed, 16 Apr 2025 12:46:17 -0700 (PDT) X-Relaying-Domain: purestorage.com Received: from dev-ushankar.dev.purestorage.com (dev-ushankar.dev.purestorage.com [IPv6:2620:125:9007:640:7:70:36:0]) by c7-smtp-2023.dev.purestorage.com (Postfix) with ESMTP id 9849F34067F; Wed, 16 Apr 2025 13:46:16 -0600 (MDT) Received: by dev-ushankar.dev.purestorage.com (Postfix, from userid 1557716368) id 95775E407EC; Wed, 16 Apr 2025 13:46:16 -0600 (MDT) From: Uday Shankar Date: Wed, 16 Apr 2025 13:46:08 -0600 Subject: [PATCH v5 4/4] ublk: mark ublk_queue as const for ublk_handle_need_get_data Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250416-ublk_task_per_io-v5-4-9261ad7bff20@purestorage.com> References: <20250416-ublk_task_per_io-v5-0-9261ad7bff20@purestorage.com> In-Reply-To: <20250416-ublk_task_per_io-v5-0-9261ad7bff20@purestorage.com> To: Ming Lei , Jens Axboe , Caleb Sander Mateos Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Uday Shankar X-Mailer: b4 0.14.2 We now allow multiple tasks to operate on I/Os belonging to the same queue concurrently. This means that any writes to ublk_queue in the I/O path are potential sources of data races. Try to prevent these by marking ublk_queue pointers as const in ublk_handle_need_get_data. Also move a bit more of the NEED_GET_DATA-specific logic into ublk_handle_need_get_data, to make the pattern in __ublk_ch_uring_cmd more uniform. Suggested-by: Ming Lei Signed-off-by: Uday Shankar Reviewed-by: Caleb Sander Mateos --- drivers/block/ublk_drv.c | 32 +++++++++++++++++++------------- 1 file changed, 19 insertions(+), 13 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 215ab45b00e10150e58d7f5ea5b5d13e40a1aa79..5f9679c03305576bee586388cab= 82a6ea5472f8b 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1291,7 +1291,7 @@ static void ublk_cmd_tw_cb(struct io_uring_cmd *cmd, ublk_dispatch_req(ubq, pdu->req, issue_flags); } =20 -static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq) +static void ublk_queue_cmd(const struct ublk_queue *ubq, struct request *r= q) { struct io_uring_cmd *cmd =3D ubq->ios[rq->tag].cmd; struct ublk_uring_cmd_pdu *pdu =3D ublk_get_uring_cmd_pdu(cmd); @@ -1813,15 +1813,6 @@ static void ublk_mark_io_ready(struct ublk_device *u= b, struct ublk_queue *ubq) mutex_unlock(&ub->mutex); } =20 -static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id, - int tag) -{ - struct ublk_queue *ubq =3D ublk_get_queue(ub, q_id); - struct request *req =3D blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag); - - ublk_queue_cmd(ubq, req); -} - static inline int ublk_check_cmd_op(u32 cmd_op) { u32 ioc_type =3D _IOC_TYPE(cmd_op); @@ -1933,6 +1924,20 @@ static int ublk_commit_and_fetch(const struct ublk_q= ueue *ubq, return 0; } =20 +static int ublk_get_data(const struct ublk_queue *ubq, struct ublk_io *io, + struct io_uring_cmd *cmd, + const struct ublksrv_io_cmd *ub_cmd, + struct request *req) +{ + if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)) + return -EINVAL; + + ublk_fill_io_cmd(io, cmd, ub_cmd->addr); + ublk_queue_cmd(ubq, req); + + return 0; +} + static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags, const struct ublksrv_io_cmd *ub_cmd) @@ -2026,10 +2031,11 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd = *cmd, goto out; break; case UBLK_IO_NEED_GET_DATA: - if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)) + ret =3D ublk_get_data( + ubq, io, cmd, ub_cmd, + blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag)); + if (ret) goto out; - ublk_fill_io_cmd(io, cmd, ub_cmd->addr); - ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag); break; default: goto out; --=20 2.34.1