[SCSI] mpt2sas: Better handling DEAD IOC (PCI-E LInk down) error condition

Detection of Dead IOC has been done in fault_reset_work thread.

If IOC Doorbell is 0xFFFFFFFF, it will be detected as non-operation/DEAD IOC.
When a DEAD IOC is detected, the code is modified to remove that IOC and
all its attached devices from OS.
The PCI layer API pci_remove_bus_device() is called to remove the dead IOC.

Signed-off-by: Nagalakshmi Nandigama <nagalakshmi.nandigama@lsi.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

3 files changed, 63 insertions, 0 deletions

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.c b/drivers/scsi/mpt2sas/mpt2sas_base.c
index beda04a8404b..c041cc70a25f 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
@@ -57,6 +57,7 @@
 #include <linux/sort.h>
 #include <linux/io.h>
 #include <linux/time.h>
+#include <linux/kthread.h>
 #include <linux/aer.h>
 
 #include "mpt2sas_base.h"
@@ -120,10 +121,34 @@ _scsih_set_fwfault_debug(const char *val, struct kernel_param *kp)
                 ioc->fwfault_debug = mpt2sas_fwfault_debug;
         return 0;
 }
+
 module_param_call(mpt2sas_fwfault_debug, _scsih_set_fwfault_debug,
     param_get_int, &mpt2sas_fwfault_debug, 0644);
 
 /**
+ *  mpt2sas_remove_dead_ioc_func - kthread context to remove dead ioc
+ * @arg: input argument, used to derive ioc
+ *
+ * Return 0 if controller is removed from pci subsystem.
+ * Return -1 for other case.
+ */
+static int mpt2sas_remove_dead_ioc_func(void *arg)
+{
+                struct MPT2SAS_ADAPTER *ioc = (struct MPT2SAS_ADAPTER *)arg;
+                struct pci_dev *pdev;
+
+                if ((ioc == NULL))
+                        return -1;
+
+                pdev = ioc->pdev;
+                if ((pdev == NULL))
+                        return -1;
+                pci_remove_bus_device(pdev);
+                return 0;
+}
+
+
+/**
  * _base_fault_reset_work - workq handling ioc fault conditions
  * @work: input argument, used to derive ioc
  * Context: sleep.
@@ -138,6 +163,7 @@ _base_fault_reset_work(struct work_struct *work)
         unsigned long    flags;
         u32 doorbell;
         int rc;
+        struct task_struct *p;
 
         spin_lock_irqsave(&ioc->ioc_reset_in_progress_lock, flags);
         if (ioc->shost_recovery)
@@ -145,6 +171,39 @@ _base_fault_reset_work(struct work_struct *work)
         spin_unlock_irqrestore(&ioc->ioc_reset_in_progress_lock, flags);
 
         doorbell = mpt2sas_base_get_iocstate(ioc, 0);
+        if ((doorbell & MPI2_IOC_STATE_MASK) == MPI2_IOC_STATE_MASK) {
+                printk(MPT2SAS_INFO_FMT "%s : SAS host is non-operational !!!!\n",
+                        ioc->name, __func__);
+
+                /*
+                 * Call _scsih_flush_pending_cmds callback so that we flush all
+                 * pending commands back to OS. This call is required to aovid
+                 * deadlock at block layer. Dead IOC will fail to do diag reset,
+                 * and this call is safe since dead ioc will never return any
+                 * command back from HW.
+                 */
+                ioc->schedule_dead_ioc_flush_running_cmds(ioc);
+                /*
+                 * Set remove_host flag early since kernel thread will
+                 * take some time to execute.
+                 */
+                ioc->remove_host = 1;
+                /*Remove the Dead Host */
+                p = kthread_run(mpt2sas_remove_dead_ioc_func, ioc,
+                    "mpt2sas_dead_ioc_%d", ioc->id);
+                if (IS_ERR(p)) {
+                        printk(MPT2SAS_ERR_FMT
+                        "%s: Running mpt2sas_dead_ioc thread failed !!!!\n",
+                        ioc->name, __func__);
+                } else {
+                    printk(MPT2SAS_ERR_FMT
+                        "%s: Running mpt2sas_dead_ioc thread success !!!!\n",
+                        ioc->name, __func__);
+                }
+
+                return; /* don't rearm timer */
+        }
+
         if ((doorbell & MPI2_IOC_STATE_MASK) == MPI2_IOC_STATE_FAULT) {
                 rc = mpt2sas_base_hard_reset_handler(ioc, CAN_SLEEP,
                     FORCE_BIG_HAMMER);
diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.h b/drivers/scsi/mpt2sas/mpt2sas_base.h
index 3c3babc7d260..61e5b2400aa8 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.h
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.h
@@ -623,6 +623,7 @@ enum mutex_type {
         TM_MUTEX_ON = 1,
 };
 
+typedef void (*MPT2SAS_FLUSH_RUNNING_CMDS)(struct MPT2SAS_ADAPTER *ioc);
 /**
  * struct MPT2SAS_ADAPTER - per adapter struct
  * @list: ioc_list
@@ -665,6 +666,7 @@ enum mutex_type {
  * @msix_vector_count: number msix vectors
  * @cpu_msix_table: table for mapping cpus to msix index
  * @cpu_msix_table_sz: table size
+ * @schedule_dead_ioc_flush_running_cmds: callback to flush pending commands
  * @scsi_io_cb_idx: shost generated commands
  * @tm_cb_idx: task management commands
  * @scsih_cb_idx: scsih internal commands
@@ -816,6 +818,7 @@ struct MPT2SAS_ADAPTER {
         resource_size_t **reply_post_host_index;
         u16             cpu_msix_table_sz;
         u32             ioc_reset_count;
+        MPT2SAS_FLUSH_RUNNING_CMDS schedule_dead_ioc_flush_running_cmds;
 
         /* internal commands, callback index */
         u8              scsi_io_cb_idx;
diff --git a/drivers/scsi/mpt2sas/mpt2sas_scsih.c b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
index d570573b7963..0b6b6b44e362 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_scsih.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
@@ -7928,6 +7928,7 @@ _scsih_probe(struct pci_dev *pdev, const struct pci_device_id *id)
         ioc->tm_tr_volume_cb_idx = tm_tr_volume_cb_idx;
         ioc->tm_sas_control_cb_idx = tm_sas_control_cb_idx;
         ioc->logging_level = logging_level;
+        ioc->schedule_dead_ioc_flush_running_cmds = &_scsih_flush_running_cmds;
         /* misc semaphores and spin locks */
         mutex_init(&ioc->reset_in_progress_mutex);
         spin_lock_init(&ioc->ioc_reset_in_progress_lock);