From bb12588a38e6db85e01dceadff7bc161fc92e7d2 Mon Sep 17 00:00:00 2001 From: David Dillow Date: Fri, 8 Oct 2010 14:40:47 -0400 Subject: [PATCH] IB/srp: Implement SRP_CRED_REQ and SRP_AER_REQ This patch adds support for SRP_CRED_REQ to avoid a lockup by targets that use that mechanism to return credits to the initiator. This prevents a lockup observed in the field where we would never add the credits from the SRP_CRED_REQ to our current count, and would therefore never send another command to the target. Minimal support for SRP_AER_REQ is also added, as these messages can also be used to convey additional credits to the initiator. Based upon extensive debugging and code by Bart Van Assche and a bug report by Chris Worley. Signed-off-by: David Dillow Signed-off-by: Roland Dreier --- drivers/infiniband/ulp/srp/ib_srp.c | 105 ++++++++++++++++++++++++++-- drivers/infiniband/ulp/srp/ib_srp.h | 8 ++- include/scsi/srp.h | 38 ++++++++++ 3 files changed, 141 insertions(+), 10 deletions(-) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index b8b09a4f012a..a54eee9324b6 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -83,6 +83,10 @@ static void srp_remove_one(struct ib_device *device); static void srp_recv_completion(struct ib_cq *cq, void *target_ptr); static void srp_send_completion(struct ib_cq *cq, void *target_ptr); static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event); +static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target, + enum srp_iu_type iu_type); +static int __srp_post_send(struct srp_target_port *target, + struct srp_iu *iu, int len); static struct scsi_transport_template *ib_srp_transport_template; @@ -896,6 +900,71 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp) spin_unlock_irqrestore(target->scsi_host->host_lock, flags); } +static int srp_response_common(struct srp_target_port *target, s32 req_delta, + void *rsp, int len) +{ + struct ib_device *dev; + unsigned long flags; + struct srp_iu *iu; + int err = 1; + + dev = target->srp_host->srp_dev->dev; + + spin_lock_irqsave(target->scsi_host->host_lock, flags); + target->req_lim += req_delta; + + iu = __srp_get_tx_iu(target, SRP_IU_RSP); + if (!iu) { + shost_printk(KERN_ERR, target->scsi_host, PFX + "no IU available to send response\n"); + goto out; + } + + ib_dma_sync_single_for_cpu(dev, iu->dma, len, DMA_TO_DEVICE); + memcpy(iu->buf, rsp, len); + ib_dma_sync_single_for_device(dev, iu->dma, len, DMA_TO_DEVICE); + + err = __srp_post_send(target, iu, len); + if (err) + shost_printk(KERN_ERR, target->scsi_host, PFX + "unable to post response: %d\n", err); + +out: + spin_unlock_irqrestore(target->scsi_host->host_lock, flags); + return err; +} + +static void srp_process_cred_req(struct srp_target_port *target, + struct srp_cred_req *req) +{ + struct srp_cred_rsp rsp = { + .opcode = SRP_CRED_RSP, + .tag = req->tag, + }; + s32 delta = be32_to_cpu(req->req_lim_delta); + + if (srp_response_common(target, delta, &rsp, sizeof rsp)) + shost_printk(KERN_ERR, target->scsi_host, PFX + "problems processing SRP_CRED_REQ\n"); +} + +static void srp_process_aer_req(struct srp_target_port *target, + struct srp_aer_req *req) +{ + struct srp_aer_rsp rsp = { + .opcode = SRP_AER_RSP, + .tag = req->tag, + }; + s32 delta = be32_to_cpu(req->req_lim_delta); + + shost_printk(KERN_ERR, target->scsi_host, PFX + "ignoring AER for LUN %llu\n", be64_to_cpu(req->lun)); + + if (srp_response_common(target, delta, &rsp, sizeof rsp)) + shost_printk(KERN_ERR, target->scsi_host, PFX + "problems processing SRP_AER_REQ\n"); +} + static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc) { struct ib_device *dev; @@ -923,6 +992,14 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc) srp_process_rsp(target, iu->buf); break; + case SRP_CRED_REQ: + srp_process_cred_req(target, iu->buf); + break; + + case SRP_AER_REQ: + srp_process_aer_req(target, iu->buf); + break; + case SRP_T_LOGOUT: /* XXX Handle target logout */ shost_printk(KERN_WARNING, target->scsi_host, @@ -985,23 +1062,36 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr) * Must be called with target->scsi_host->host_lock held to protect * req_lim and tx_head. Lock cannot be dropped between call here and * call to __srp_post_send(). + * + * Note: + * An upper limit for the number of allocated information units for each + * request type is: + * - SRP_IU_CMD: SRP_CMD_SQ_SIZE, since the SCSI mid-layer never queues + * more than Scsi_Host.can_queue requests. + * - SRP_IU_TSK_MGMT: SRP_TSK_MGMT_SQ_SIZE. + * - SRP_IU_RSP: 1, since a conforming SRP target never sends more than + * one unanswered SRP request to an initiator. */ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target, - enum srp_request_type req_type) + enum srp_iu_type iu_type) { - s32 rsv = (req_type == SRP_REQ_TASK_MGMT) ? 0 : SRP_TSK_MGMT_SQ_SIZE; + s32 rsv = (iu_type == SRP_IU_TSK_MGMT) ? 0 : SRP_TSK_MGMT_SQ_SIZE; + struct srp_iu *iu; srp_send_completion(target->send_cq, target); if (target->tx_head - target->tx_tail >= SRP_SQ_SIZE) return NULL; - if (target->req_lim <= rsv) { + /* Initiator responses to target requests do not consume credits */ + if (target->req_lim <= rsv && iu_type != SRP_IU_RSP) { ++target->zero_req_lim; return NULL; } - return target->tx_ring[target->tx_head & SRP_SQ_MASK]; + iu = target->tx_ring[target->tx_head & SRP_SQ_MASK]; + iu->type = iu_type; + return iu; } /* @@ -1030,7 +1120,8 @@ static int __srp_post_send(struct srp_target_port *target, if (!ret) { ++target->tx_head; - --target->req_lim; + if (iu->type != SRP_IU_RSP) + --target->req_lim; } return ret; @@ -1056,7 +1147,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd, return 0; } - iu = __srp_get_tx_iu(target, SRP_REQ_NORMAL); + iu = __srp_get_tx_iu(target, SRP_IU_CMD); if (!iu) goto err; @@ -1363,7 +1454,7 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target, init_completion(&req->done); - iu = __srp_get_tx_iu(target, SRP_REQ_TASK_MGMT); + iu = __srp_get_tx_iu(target, SRP_IU_TSK_MGMT); if (!iu) goto out; diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h index 7a959d5f2fa6..ed0dce9e479f 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.h +++ b/drivers/infiniband/ulp/srp/ib_srp.h @@ -82,9 +82,10 @@ enum srp_target_state { SRP_TARGET_REMOVED }; -enum srp_request_type { - SRP_REQ_NORMAL, - SRP_REQ_TASK_MGMT, +enum srp_iu_type { + SRP_IU_CMD, + SRP_IU_TSK_MGMT, + SRP_IU_RSP, }; struct srp_device { @@ -171,6 +172,7 @@ struct srp_iu { void *buf; size_t size; enum dma_data_direction direction; + enum srp_iu_type type; }; #endif /* IB_SRP_H */ diff --git a/include/scsi/srp.h b/include/scsi/srp.h index ad178fa78f66..1ae84db4c9fb 100644 --- a/include/scsi/srp.h +++ b/include/scsi/srp.h @@ -239,4 +239,42 @@ struct srp_rsp { u8 data[0]; } __attribute__((packed)); +struct srp_cred_req { + u8 opcode; + u8 sol_not; + u8 reserved[2]; + __be32 req_lim_delta; + u64 tag; +}; + +struct srp_cred_rsp { + u8 opcode; + u8 reserved[7]; + u64 tag; +}; + +/* + * The SRP spec defines the fixed portion of the AER_REQ structure to be + * 36 bytes, so it needs to be packed to avoid having it padded to 40 bytes + * on 64-bit architectures. + */ +struct srp_aer_req { + u8 opcode; + u8 sol_not; + u8 reserved[2]; + __be32 req_lim_delta; + u64 tag; + u32 reserved2; + __be64 lun; + __be32 sense_data_len; + u32 reserved3; + u8 sense_data[0]; +} __attribute__((packed)); + +struct srp_aer_rsp { + u8 opcode; + u8 reserved[7]; + u64 tag; +}; + #endif /* SCSI_SRP_H */ -- 2.39.2