[SCSI] fnic: fixing issues in device and firmware reset code

1. Handling overlapped firmware resets
     This fix serialize multiple firmware resets to avoid situation where fnic
     device fails to come up for link up event, when firmware resets are issued
     back to back. If there are overlapped firmware resets are issued,
     the firmware reset operation checks whether there is any firmware reset in
     progress, if so it polls for its completion in a loop with 100ms delay.

2. Handling device reset timeout
     fnic_device_reset code has been modified to handle Device reset timeout:
     - Issue terminate on device reset timeout.
     - Introduced flags field (one of the scratch fields in scsi_cmnd).
     With this, device reset request would have DEVICE_RESET flag set for other
     routines to determine the type of the request.
     Also modified fnic_terminate_rport_io, fnic_rport_exch_rset, completion
     routines to handle SCSI commands with DEVICE_RESET flag.

3. LUN/Device Reset hangs when issued through IOCTL using utilities like
   sg_reset.
     Each SCSI command is associated with a valid tag, fnic uses this tag to
     retrieve associated scsi command on completion. the LUN/Device Reset issued
     through IOCTL resulting into a SCSI command that is not associated with a
     valid tag. So fnic fails to retrieve associated scsi command on completion,
     which causes hang. This fix allocates tag, associates it with the
     scsi command and frees the tag, when the operation completed.

4. Preventing IOs during firmware reset.
     Current fnic implementation allows IO submissions during firmware reset.
     This fix synchronizes IO submissions and firmware reset operations.
     It ensures that IOs issued to fnic prior to reset will be issued to the
     firmware before firmware reset.
Signed-off-by: Narsimhulu Musini <nmusini@cisco.com>
Signed-off-by: Hiral Patel <hiralpat@cisco.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/fnic/fnic.h

@@ -55,6 +55,19 @@
 #define FNIC_TAG_MASK		(BIT(24) - 1)	/* mask for lookup */
 #define FNIC_NO_TAG             -1
 
+/*
+ * Command flags to identify the type of command and for other future
+ * use.
+ */
+#define FNIC_NO_FLAGS			0
+#define FNIC_CDB_REQ			BIT(1)	/* All IOs with a valid CDB */
+#define FNIC_BLOCKING_REQ		BIT(2)	/* All blocking Requests */
+#define FNIC_DEVICE_RESET		BIT(3)	/* Device reset request */
+#define FNIC_DEV_RST_PENDING		BIT(4)	/* Device reset pending */
+#define FNIC_DEV_RST_TIMED_OUT		BIT(5)	/* Device reset timed out */
+#define FNIC_DEV_RST_TERM_ISSUED	BIT(6)	/* Device reset terminate */
+#define FNIC_DEV_RST_DONE		BIT(7)	/* Device reset done */
+
 /*
  * Usage of the scsi_cmnd scratchpad.
  * These fields are locked by the hashed io_req_lock.
@@ -64,6 +77,7 @@
 #define CMD_ABTS_STATUS(Cmnd)	((Cmnd)->SCp.Message)
 #define CMD_LR_STATUS(Cmnd)	((Cmnd)->SCp.have_data_in)
 #define CMD_TAG(Cmnd)           ((Cmnd)->SCp.sent_command)
+#define CMD_FLAGS(Cmnd)         ((Cmnd)->SCp.Status)
 
 #define FCPIO_INVALID_CODE 0x100 /* hdr_status value unused by firmware */
 
@@ -71,9 +85,28 @@
 #define FNIC_HOST_RESET_TIMEOUT	     10000	/* mSec */
 #define FNIC_RMDEVICE_TIMEOUT        1000       /* mSec */
 #define FNIC_HOST_RESET_SETTLE_TIME  30         /* Sec */
+#define FNIC_ABT_TERM_DELAY_TIMEOUT  500        /* mSec */
 
 #define FNIC_MAX_FCP_TARGET     256
 
+/**
+ * state_flags to identify host state along along with fnic's state
+ **/
+#define __FNIC_FLAGS_FWRESET		BIT(0) /* fwreset in progress */
+#define __FNIC_FLAGS_BLOCK_IO		BIT(1) /* IOs are blocked */
+
+#define FNIC_FLAGS_NONE			(0)
+#define FNIC_FLAGS_FWRESET		(__FNIC_FLAGS_FWRESET | \
+					__FNIC_FLAGS_BLOCK_IO)
+
+#define FNIC_FLAGS_IO_BLOCKED		(__FNIC_FLAGS_BLOCK_IO)
+
+#define fnic_set_state_flags(fnicp, st_flags)	\
+	__fnic_set_state_flags(fnicp, st_flags, 0)
+
+#define fnic_clear_state_flags(fnicp, st_flags)  \
+	__fnic_set_state_flags(fnicp, st_flags, 1)
+
 extern unsigned int fnic_log_level;
 
 #define FNIC_MAIN_LOGGING 0x01
@@ -170,6 +203,9 @@ struct fnic {
 
 	struct completion *remove_wait; /* device remove thread blocks */
 
+	atomic_t in_flight;		/* io counter */
+	u32 _reserved;			/* fill hole */
+	unsigned long state_flags;	/* protected by host lock */
 	enum fnic_state state;
 	spinlock_t fnic_lock;
 
@@ -267,4 +303,10 @@ const char *fnic_state_to_str(unsigned int state);
 void fnic_log_q_error(struct fnic *fnic);
 void fnic_handle_link_event(struct fnic *fnic);
 
+static inline int
+fnic_chk_state_flags_locked(struct fnic *fnic, unsigned long st_flags)
+{
+	return ((fnic->state_flags & st_flags) == st_flags);
+}
+void __fnic_set_state_flags(struct fnic *, unsigned long, unsigned long);
 #endif /* _FNIC_H_ */

drivers/scsi/fnic/fnic_main.c

@@ -624,6 +624,9 @@ static int fnic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	}
 	fnic->state = FNIC_IN_FC_MODE;
 
+	atomic_set(&fnic->in_flight, 0);
+	fnic->state_flags = FNIC_FLAGS_NONE;
+
 	/* Enable hardware stripping of vlan header on ingress */
 	fnic_set_nic_config(fnic, 0, 0, 0, 0, 0, 0, 1);