cxlflash: Base error recovery support

Introduce support for enhanced I/O error handling.

A device state is added to track 3 possible states of the device:

Normal - the device is operating normally and is fully operational

Limbo - the device is in a reset/recovery scenario and its operational
        status is paused

Failed/terminating - the device has either failed to be reset/recovered
                     or is being terminated (removed); it is no longer
                     operational

All operations are allowed when the device is operating normally. When the
device transitions to limbo state, I/O must be paused. To help accomplish
this, a wait queue is introduced where existing and new threads can wait
until the device is no longer in limbo. When coming out of limbo, threads
need to check the state and error out gracefully when encountering the
failed state. When the device transitions to the failed/terminating state,
normal operations are no longer allowed. Only specially designated
operations related to graceful cleanup are permitted.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Reviewed-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h
index 5f43608dc8a1..ffdbc572d180 100644
--- a/drivers/scsi/cxlflash/common.h
+++ b/drivers/scsi/cxlflash/common.h
@@ -76,6 +76,12 @@ enum cxlflash_init_state {
 	INIT_STATE_SCSI
 };
 
+enum cxlflash_state {
+	STATE_NORMAL,	/* Normal running state, everything good */
+	STATE_LIMBO,	/* Limbo running state, trying to reset/recover */
+	STATE_FAILTERM	/* Failed/terminating state, error out users/threads */
+};
+
 /*
  * Each context has its own set of resource handles that is visible
  * only from that context.
@@ -91,8 +97,6 @@ struct cxlflash_cfg {
 
 	ulong cxlflash_regs_pci;
 
-	wait_queue_head_t eeh_waitq;
-
 	struct work_struct work_q;
 	enum cxlflash_init_state init_state;
 	enum cxlflash_lr_state lr_state;
@@ -105,7 +109,8 @@ struct cxlflash_cfg {
 
 	wait_queue_head_t tmf_waitq;
 	bool tmf_active;
-	u8 err_recovery_active:1;
+	wait_queue_head_t limbo_waitq;
+	enum cxlflash_state state;
 };
 
 struct afu_cmd {