From b45cdbaf9f7f0486847c52f60747fb108724652a Mon Sep 17 00:00:00 2001 From: Manoj Kumar Date: Mon, 14 Dec 2015 15:07:23 -0600 Subject: [PATCH] cxlflash: Resolve oops in wait_port_offline If an async error interrupt is generated, and the error requires the FC link to be reset, it cannot be performed in the interrupt context. So a work element is scheduled to complete the link reset in a process context. If either an EEH event or an escalation occurs in between when the interrupt is generated and the scheduled work is started, the MMIO space may no longer be available. This will cause an oops in the worker thread. [ 606.806583] NIP kthread_data+0x28/0x40 [ 606.806633] LR wq_worker_sleeping+0x30/0x100 [ 606.806694] Call Trace: [ 606.806721] 0x50 (unreliable) [ 606.806796] wq_worker_sleeping+0x30/0x100 [ 606.806884] __schedule+0x69c/0x8a0 [ 606.806959] schedule+0x44/0xc0 [ 606.807034] do_exit+0x770/0xb90 [ 606.807109] die+0x300/0x460 [ 606.807185] bad_page_fault+0xd8/0x150 [ 606.807259] handle_page_fault+0x2c/0x30 [ 606.807338] wait_port_offline.constprop.12+0x60/0x130 [cxlflash] To prevent the problem space area from being unmapped, when there is pending work, a mapcount (using the kref mechanism) is held. The mapcount is released only when the work is completed. The last reference release is tied to the unmapping service. Signed-off-by: Manoj N. Kumar Acked-by: Matthew R. Ochs Reviewed-by: Uma Krishnan Signed-off-by: Martin K. Petersen --- drivers/scsi/cxlflash/common.h | 2 ++ drivers/scsi/cxlflash/main.c | 27 ++++++++++++++++++++++++--- 2 files changed, 26 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h index c11cd193f896..5ada9268a450 100644 --- a/drivers/scsi/cxlflash/common.h +++ b/drivers/scsi/cxlflash/common.h @@ -165,6 +165,8 @@ struct afu { struct sisl_host_map __iomem *host_map; /* MC host map */ struct sisl_ctrl_map __iomem *ctrl_map; /* MC control map */ + struct kref mapcount; + ctx_hndl_t ctx_hndl; /* master's context handle */ u64 *hrrq_start; u64 *hrrq_end; diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c index ac39856a74b4..30542ca9415b 100644 --- a/drivers/scsi/cxlflash/main.c +++ b/drivers/scsi/cxlflash/main.c @@ -368,6 +368,7 @@ static int send_cmd(struct afu *afu, struct afu_cmd *cmd) no_room: afu->read_room = true; + kref_get(&cfg->afu->mapcount); schedule_work(&cfg->work_q); rc = SCSI_MLQUEUE_HOST_BUSY; goto out; @@ -473,6 +474,16 @@ static int send_tmf(struct afu *afu, struct scsi_cmnd *scp, u64 tmfcmd) return rc; } +static void afu_unmap(struct kref *ref) +{ + struct afu *afu = container_of(ref, struct afu, mapcount); + + if (likely(afu->afu_map)) { + cxl_psa_unmap((void __iomem *)afu->afu_map); + afu->afu_map = NULL; + } +} + /** * cxlflash_driver_info() - information handler for this host driver * @host: SCSI host associated with device. @@ -503,6 +514,7 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) ulong lock_flags; short lflag = 0; int rc = 0; + int kref_got = 0; dev_dbg_ratelimited(dev, "%s: (scp=%p) %d/%d/%d/%llu " "cdb=(%08X-%08X-%08X-%08X)\n", @@ -547,6 +559,9 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) goto out; } + kref_get(&cfg->afu->mapcount); + kref_got = 1; + cmd->rcb.ctx_id = afu->ctx_hndl; cmd->rcb.port_sel = port_sel; cmd->rcb.lun_id = lun_to_lunid(scp->device->lun); @@ -587,6 +602,8 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp) } out: + if (kref_got) + kref_put(&afu->mapcount, afu_unmap); pr_devel("%s: returning rc=%d\n", __func__, rc); return rc; } @@ -661,6 +678,7 @@ static void stop_afu(struct cxlflash_cfg *cfg) cxl_psa_unmap((void __iomem *)afu->afu_map); afu->afu_map = NULL; } + kref_put(&afu->mapcount, afu_unmap); } } @@ -746,8 +764,8 @@ static void cxlflash_remove(struct pci_dev *pdev) scsi_remove_host(cfg->host); /* fall through */ case INIT_STATE_AFU: - term_afu(cfg); cancel_work_sync(&cfg->work_q); + term_afu(cfg); case INIT_STATE_PCI: pci_release_regions(cfg->dev); pci_disable_device(pdev); @@ -1331,6 +1349,7 @@ static irqreturn_t cxlflash_async_err_irq(int irq, void *data) __func__, port); cfg->lr_state = LINK_RESET_REQUIRED; cfg->lr_port = port; + kref_get(&cfg->afu->mapcount); schedule_work(&cfg->work_q); } @@ -1351,6 +1370,7 @@ static irqreturn_t cxlflash_async_err_irq(int irq, void *data) if (info->action & SCAN_HOST) { atomic_inc(&cfg->scan_host_needed); + kref_get(&cfg->afu->mapcount); schedule_work(&cfg->work_q); } } @@ -1746,6 +1766,7 @@ static int init_afu(struct cxlflash_cfg *cfg) rc = -ENOMEM; goto err1; } + kref_init(&afu->mapcount); /* No byte reverse on reading afu_version or string will be backwards */ reg = readq(&afu->afu_map->global.regs.afu_version); @@ -1780,8 +1801,7 @@ static int init_afu(struct cxlflash_cfg *cfg) return rc; err2: - cxl_psa_unmap((void __iomem *)afu->afu_map); - afu->afu_map = NULL; + kref_put(&afu->mapcount, afu_unmap); err1: term_mc(cfg, UNDO_START); goto out; @@ -2354,6 +2374,7 @@ static void cxlflash_worker_thread(struct work_struct *work) if (atomic_dec_if_positive(&cfg->scan_host_needed) >= 0) scsi_scan_host(cfg->host); + kref_put(&afu->mapcount, afu_unmap); } /**