| Message ID | 20240510202313.25209-6-bvanassche@acm.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Five nbd patches | expand |
On Fri, May 10, 2024 at 01:23:13PM -0700, Bart Van Assche wrote: > Both nbd_send_cmd() and nbd_handle_cmd() return either a negative error > number or a positive blk_status_t value. Eww. Please split these into separate values instead. There is a reason why blk_status_t is a separate type with sparse checks, and drivers really shouldn't do avoid with that for a tiny micro-optimization of the calling convention (if this even is one and not just the driver being sloppy).
On 5/20/24 05:41, Christoph Hellwig wrote: > On Fri, May 10, 2024 at 01:23:13PM -0700, Bart Van Assche wrote: >> Both nbd_send_cmd() and nbd_handle_cmd() return either a negative error >> number or a positive blk_status_t value. > > Eww. Please split these into separate values instead. There is a reason > why blk_status_t is a separate type with sparse checks, and drivers > really shouldn't do avoid with that for a tiny micro-optimization of > the calling convention (if this even is one and not just the driver > being sloppy). How about the (untested) patch below? Thanks, Bart. diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 22a79a62cc4e..4ee76c39e3a5 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -588,11 +588,17 @@ static inline int was_interrupted(int result) return result == -ERESTARTSYS || result == -EINTR; } +struct send_res { + int result; + blk_status_t status; +}; + /* * Returns BLK_STS_RESOURCE if the caller should retry after a delay. Returns * -EAGAIN if the caller should requeue @cmd. Returns -EIO if sending failed. */ -static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) +static struct send_res nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, + int index) { struct request *req = blk_mq_rq_from_pdu(cmd); struct nbd_config *config = nbd->config; @@ -614,13 +620,13 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) type = req_to_nbd_cmd_type(req); if (type == U32_MAX) - return -EIO; + return (struct send_res){ .result = -EIO }; if (rq_data_dir(req) == WRITE && (config->flags & NBD_FLAG_READ_ONLY)) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Write on read-only\n"); - return -EIO; + return (struct send_res){ .result = -EIO }; } if (req->cmd_flags & REQ_FUA) @@ -674,11 +680,11 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->sent = sent; } set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return (__force int)BLK_STS_RESOURCE; + return (struct send_res){ .status = BLK_STS_RESOURCE }; } dev_err_ratelimited(disk_to_dev(nbd->disk), "Send control failed (result %d)\n", result); - return -EAGAIN; + return (struct send_res){ .result = -EAGAIN }; } send_pages: if (type != NBD_CMD_WRITE) @@ -715,12 +721,14 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->pending = req; nsock->sent = sent; set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return (__force int)BLK_STS_RESOURCE; + return (struct send_res){ + .status = BLK_STS_RESOURCE + }; } dev_err(disk_to_dev(nbd->disk), "Send data failed (result %d)\n", result); - return -EAGAIN; + return (struct send_res){ .result = -EAGAIN }; } /* * The completion might already have come in, @@ -737,7 +745,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) trace_nbd_payload_sent(req, handle); nsock->pending = NULL; nsock->sent = 0; - return 0; + return (struct send_res){}; } static int nbd_read_reply(struct nbd_device *nbd, struct socket *sock, @@ -1018,7 +1026,8 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) struct nbd_device *nbd = cmd->nbd; struct nbd_config *config; struct nbd_sock *nsock; - int ret; + struct send_res send_res; + blk_status_t ret; lockdep_assert_held(&cmd->lock); @@ -1076,14 +1085,15 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) * Some failures are related to the link going down, so anything that * returns EAGAIN can be retried on a different socket. */ - ret = nbd_send_cmd(nbd, cmd, index); - /* - * Access to this flag is protected by cmd->lock, thus it's safe to set - * the flag after nbd_send_cmd() succeed to send request to server. - */ - if (!ret) + send_res = nbd_send_cmd(nbd, cmd, index); + ret = send_res.result < 0 ? BLK_STS_IOERR : send_res.status; + if (ret == BLK_STS_OK) { + /* + * cmd->lock is held. Hence, it's safe to set this flag after + * nbd_send_cmd() succeeded sending the request to the server. + */ __set_bit(NBD_CMD_INFLIGHT, &cmd->flags); - else if (ret == -EAGAIN) { + } else if (send_res.result == -EAGAIN) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Request send failed, requeueing\n"); nbd_mark_nsock_dead(nbd, nsock, 1); @@ -1093,7 +1103,7 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) out: mutex_unlock(&nsock->tx_lock); nbd_config_put(nbd); - return ret < 0 ? BLK_STS_IOERR : (__force blk_status_t)ret; + return ret; } static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 29e43ab1650c..22a79a62cc4e 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -588,6 +588,10 @@ static inline int was_interrupted(int result) return result == -ERESTARTSYS || result == -EINTR; } +/* + * Returns BLK_STS_RESOURCE if the caller should retry after a delay. Returns + * -EAGAIN if the caller should requeue @cmd. Returns -EIO if sending failed. + */ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) { struct request *req = blk_mq_rq_from_pdu(cmd); @@ -670,7 +674,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->sent = sent; } set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return BLK_STS_RESOURCE; + return (__force int)BLK_STS_RESOURCE; } dev_err_ratelimited(disk_to_dev(nbd->disk), "Send control failed (result %d)\n", result); @@ -711,7 +715,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->pending = req; nsock->sent = sent; set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return BLK_STS_RESOURCE; + return (__force int)BLK_STS_RESOURCE; } dev_err(disk_to_dev(nbd->disk), "Send data failed (result %d)\n", @@ -1008,7 +1012,7 @@ static int wait_for_reconnect(struct nbd_device *nbd) return !test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags); } -static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) +static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) { struct request *req = blk_mq_rq_from_pdu(cmd); struct nbd_device *nbd = cmd->nbd; @@ -1022,14 +1026,14 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) if (!config) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Socks array is empty\n"); - return -EINVAL; + return BLK_STS_IOERR; } if (index >= config->num_connections) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Attempted send on invalid socket\n"); nbd_config_put(nbd); - return -EINVAL; + return BLK_STS_IOERR; } cmd->status = BLK_STS_OK; again: @@ -1052,7 +1056,7 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) */ sock_shutdown(nbd); nbd_config_put(nbd); - return -EIO; + return BLK_STS_IOERR; } goto again; } @@ -1065,7 +1069,7 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) blk_mq_start_request(req); if (unlikely(nsock->pending && nsock->pending != req)) { nbd_requeue_cmd(cmd); - ret = 0; + ret = BLK_STS_OK; goto out; } /* @@ -1084,19 +1088,19 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) "Request send failed, requeueing\n"); nbd_mark_nsock_dead(nbd, nsock, 1); nbd_requeue_cmd(cmd); - ret = 0; + ret = BLK_STS_OK; } out: mutex_unlock(&nsock->tx_lock); nbd_config_put(nbd); - return ret; + return ret < 0 ? BLK_STS_IOERR : (__force blk_status_t)ret; } static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd) { struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq); - int ret; + blk_status_t ret; /* * Since we look at the bio's to send the request over the network we @@ -1116,10 +1120,6 @@ static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx, * appropriate. */ ret = nbd_handle_cmd(cmd, hctx->queue_num); - if (ret < 0) - ret = BLK_STS_IOERR; - else if (!ret) - ret = BLK_STS_OK; mutex_unlock(&cmd->lock); return ret;
Both nbd_send_cmd() and nbd_handle_cmd() return either a negative error number or a positive blk_status_t value. nbd_queue_rq() converts these return values into a blk_status_t value. There is a bug in the conversion code: if nbd_send_cmd() returns BLK_STS_RESOURCE, nbd_queue_rq() should return BLK_STS_RESOURCE instead of BLK_STS_OK. Fix this, move the conversion code into nbd_handle_cmd() and fix the remaining sparse warnings. This patch fixes the following sparse warnings: drivers/block/nbd.c:673:32: warning: incorrect type in return expression (different base types) drivers/block/nbd.c:673:32: expected int drivers/block/nbd.c:673:32: got restricted blk_status_t [usertype] drivers/block/nbd.c:714:48: warning: incorrect type in return expression (different base types) drivers/block/nbd.c:714:48: expected int drivers/block/nbd.c:714:48: got restricted blk_status_t [usertype] drivers/block/nbd.c:1120:21: warning: incorrect type in assignment (different base types) drivers/block/nbd.c:1120:21: expected int [assigned] ret drivers/block/nbd.c:1120:21: got restricted blk_status_t [usertype] drivers/block/nbd.c:1125:16: warning: incorrect type in return expression (different base types) drivers/block/nbd.c:1125:16: expected restricted blk_status_t drivers/block/nbd.c:1125:16: got int [assigned] ret Cc: Christoph Hellwig <hch@lst.de> Cc: Josef Bacik <jbacik@fb.com> Cc: Yu Kuai <yukuai3@huawei.com> Cc: Markus Pargmann <mpa@pengutronix.de> Fixes: fc17b6534eb8 ("blk-mq: switch ->queue_rq return value to blk_status_t") Cc: stable@vger.kernel.org Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- drivers/block/nbd.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-)