ncr5380: Change instance->host_lock to hostdata->lock

NCR5380.c presently uses the instance->host_lock spin lock. Convert this
to a new spin lock that protects the NCR5380_hostdata struct.

atari_NCR5380.c previously used local_irq_save/restore() rather than a
spin lock. Convert this to hostdata->lock in irq mode. For SMP platforms,
the interrupt handler now also acquires the spin lock.

This brings all locking in the two core drivers into agreement.

Adding this locking also means that a bunch of volatile qualifiers can be
removed from the members of the NCR5380_hostdata struct. This is done in
a subsequent patch.

Proper locking will allow the abort handler to locate a command being
aborted. This is presently impossible if the abort handler is invoked when
the command has been moved from a queue to a pointer on the stack. (If
eh_abort_handler can't determine whether a command has been completed
or is still being processed then it can't decide whether to return
success or failure.)

The hostdata spin lock is now held when calling NCR5380_select() and
NCR5380_information_transfer(). Where possible, the lock is dropped for
polling and PIO transfers.

Clean up the now-redundant SELECT_ENABLE_REG writes, that used to provide
limited mutual exclusion between information_transfer() and reselect().

Accessing hostdata->connected without data races means taking the lock;
cleanup these accesses.

The new spin lock falls away for m68k and other UP builds, so this should
have little impact there. In the SMP case the new lock should be
uncontested even when the SCSI bus is contested.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index a4defd1977c957b0bc8bd204e2306f125b750399..5209f346ae80e3435779ba666b1b4867fb4673b0 100644 (file)
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -612,6 +612,7 @@ static int __maybe_unused NCR5380_show_info(struct seq_file *m,
 {
        struct NCR5380_hostdata *hostdata;
        struct scsi_cmnd *ptr;
+       unsigned long flags;
 
        hostdata = (struct NCR5380_hostdata *) instance->hostdata;
 
@@ -619,7 +620,7 @@ static int __maybe_unused NCR5380_show_info(struct seq_file *m,
        seq_printf(m, "Highwater I/O busy spin counts: write %d, read %d\n",
                hostdata->spin_max_w, hostdata->spin_max_r);
 #endif
-       spin_lock_irq(instance->host_lock);
+       spin_lock_irqsave(&hostdata->lock, flags);
        if (!hostdata->connected)
                seq_printf(m, "scsi%d: no currently connected command\n", instance->host_no);
        else
@@ -631,7 +632,7 @@ static int __maybe_unused NCR5380_show_info(struct seq_file *m,
        seq_printf(m, "scsi%d: disconnected_queue\n", instance->host_no);
        for (ptr = (struct scsi_cmnd *) hostdata->disconnected_queue; ptr; ptr = (struct scsi_cmnd *) ptr->host_scribble)
                lprint_Scsi_Cmnd(ptr, m);
-       spin_unlock_irq(instance->host_lock);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
        return 0;
 }
 
@@ -691,6 +692,7 @@ static int NCR5380_init(struct Scsi_Host *instance, int flags)
 #ifdef REAL_DMA
        hostdata->dmalen = 0;
 #endif
+       spin_lock_init(&hostdata->lock);
        hostdata->connected = NULL;
        hostdata->issue_queue = NULL;
        hostdata->disconnected_queue = NULL;
@@ -830,7 +832,7 @@ static int NCR5380_queue_command(struct Scsi_Host *instance,
        cmd->host_scribble = NULL;
        cmd->result = 0;
 
-       spin_lock_irqsave(instance->host_lock, flags);
+       spin_lock_irqsave(&hostdata->lock, flags);
 
        /* 
         * Insert the cmd into the issue queue. Note that REQUEST SENSE 
@@ -848,7 +850,7 @@ static int NCR5380_queue_command(struct Scsi_Host *instance,
                LIST(cmd, tmp);
                tmp->host_scribble = (unsigned char *) cmd;
        }
-       spin_unlock_irqrestore(instance->host_lock, flags);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
 
        dprintk(NDEBUG_QUEUES, "scsi%d : command added to %s of queue\n", instance->host_no, (cmd->cmnd[0] == REQUEST_SENSE) ? "head" : "tail");
 
@@ -877,10 +879,10 @@ static void NCR5380_main(struct work_struct *work)
        struct scsi_cmnd *tmp, *prev;
        int done;
        
-       spin_lock_irq(instance->host_lock);
+       spin_lock_irq(&hostdata->lock);
        do {
-               /* Lock held here */
                done = 1;
+
                if (!hostdata->connected) {
                        dprintk(NDEBUG_MAIN, "scsi%d : not connected\n", instance->host_no);
                        /*
@@ -930,11 +932,10 @@ static void NCR5380_main(struct work_struct *work)
                                        }
                                        if (hostdata->connected)
                                                break;
-                                       /* lock held here still */
                                }       /* if target/lun is not busy */
                        }       /* for */
-                       /* exited locked */
                }       /* if (!hostdata->connected) */
+
                if (hostdata->connected
 #ifdef REAL_DMA
                    && !hostdata->dmalen
@@ -946,8 +947,7 @@ static void NCR5380_main(struct work_struct *work)
                        done = 0;
                }
        } while (!done);
-       
-       spin_unlock_irq(instance->host_lock);
+       spin_unlock_irq(&hostdata->lock);
 }
 
 #ifndef DONT_USE_INTR
@@ -994,7 +994,7 @@ static irqreturn_t NCR5380_intr(int irq, void *dev_id)
        unsigned char basr;
        unsigned long flags;
 
-       spin_lock_irqsave(instance->host_lock, flags);
+       spin_lock_irqsave(&hostdata->lock, flags);
 
        basr = NCR5380_read(BUS_AND_STATUS_REG);
        if (basr & BASR_IRQ) {
@@ -1058,7 +1058,7 @@ static irqreturn_t NCR5380_intr(int irq, void *dev_id)
                shost_printk(KERN_NOTICE, instance, "interrupt without IRQ bit\n");
        }
 
-       spin_unlock_irqrestore(instance->host_lock, flags);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
 
        return IRQ_RETVAL(handled);
 }
@@ -1125,11 +1125,11 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
         * Bus Free Delay, arbitration will begin.
         */
 
-       spin_unlock_irq(instance->host_lock);
+       spin_unlock_irq(&hostdata->lock);
        err = NCR5380_poll_politely2(instance, MODE_REG, MR_ARBITRATE, 0,
                        INITIATOR_COMMAND_REG, ICR_ARBITRATION_PROGRESS,
                                               ICR_ARBITRATION_PROGRESS, HZ);
-       spin_lock_irq(instance->host_lock);
+       spin_lock_irq(&hostdata->lock);
        if (!(NCR5380_read(MODE_REG) & MR_ARBITRATE)) {
                /* Reselection interrupt */
                return -1;
@@ -1140,6 +1140,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
                             "select: arbitration timeout\n");
                return -1;
        }
+       spin_unlock_irq(&hostdata->lock);
 
        /* The SCSI-2 arbitration delay is 2.4 us */
        udelay(3);
@@ -1148,6 +1149,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        if ((NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) || (NCR5380_read(CURRENT_SCSI_DATA_REG) & hostdata->id_higher_mask) || (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST)) {
                NCR5380_write(MODE_REG, MR_BASE);
                dprintk(NDEBUG_ARBITRATION, "scsi%d : lost arbitration, deasserting MR_ARBITRATE\n", instance->host_no);
+               spin_lock_irq(&hostdata->lock);
                return -1;
        }
 
@@ -1168,6 +1170,8 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        else
                udelay(2);
 
+       spin_lock_irq(&hostdata->lock);
+
        /* NCR5380_reselect() clears MODE_REG after a reselection interrupt */
        if (!(NCR5380_read(MODE_REG) & MR_ARBITRATE))
                return -1;
@@ -1196,6 +1200,8 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
         */
        NCR5380_write(SELECT_ENABLE_REG, 0);
 
+       spin_unlock_irq(&hostdata->lock);
+
        /*
         * The initiator shall then wait at least two deskew delays and release 
         * the BSY signal.
@@ -1235,6 +1241,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
                                    msecs_to_jiffies(250));
 
        if ((NCR5380_read(STATUS_REG) & (SR_SEL | SR_IO)) == (SR_SEL | SR_IO)) {
+               spin_lock_irq(&hostdata->lock);
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                NCR5380_reselect(instance);
                if (!hostdata->connected)
@@ -1244,6 +1251,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        }
 
        if (err < 0) {
+               spin_lock_irq(&hostdata->lock);
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                cmd->result = DID_BAD_TARGET << 16;
                cmd->scsi_done(cmd);
@@ -1280,9 +1288,8 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 
        /* Wait for start of REQ/ACK handshake */
 
-       spin_unlock_irq(instance->host_lock);
        err = NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
-       spin_lock_irq(instance->host_lock);
+       spin_lock_irq(&hostdata->lock);
        if (err < 0) {
                shost_printk(KERN_ERR, instance, "select: REQ timeout\n");
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
@@ -1302,6 +1309,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        NCR5380_transfer_pio(instance, &phase, &len, &data);
        dprintk(NDEBUG_SELECTION, "scsi%d : nexus established.\n", instance->host_no);
        /* XXX need to handle errors here */
+
        hostdata->connected = cmd;
        hostdata->busy[cmd->device->id] |= (1 << (cmd->device->lun & 0xFF));
 
@@ -1805,9 +1813,9 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance) {
 #endif
        unsigned char *data;
        unsigned char phase, tmp, extended_msg[10], old_phase = 0xff;
-       struct scsi_cmnd *cmd = (struct scsi_cmnd *) hostdata->connected;
+       struct scsi_cmnd *cmd;
 
-       while (1) {
+       while ((cmd = hostdata->connected)) {
                tmp = NCR5380_read(STATUS_REG);
                /* We only have a valid SCSI phase when REQ is asserted */
                if (tmp & SR_REQ) {
@@ -1883,8 +1891,12 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance) {
                                                cmd->SCp.this_residual -= transfersize - len;
                                } else
 #endif                         /* defined(PSEUDO_DMA) || defined(REAL_DMA_POLL) */
+                               {
+                                       spin_unlock_irq(&hostdata->lock);
                                        NCR5380_transfer_pio(instance, &phase, (int *) &cmd->SCp.this_residual, (unsigned char **)
                                                             &cmd->SCp.ptr);
+                                       spin_lock_irq(&hostdata->lock);
+                               }
                                break;
                        case PHASE_MSGIN:
                                len = 1;
@@ -2016,6 +2028,9 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance) {
                                        extended_msg[0] = EXTENDED_MESSAGE;
                                        /* Accept first byte by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
+
+                                       spin_unlock_irq(&hostdata->lock);
+
                                        dprintk(NDEBUG_EXTENDED, "scsi%d : receiving extended message\n", instance->host_no);
 
                                        len = 2;
@@ -2050,6 +2065,11 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance) {
                                                printk("scsi%d: extended message code %02x length %d is too long\n", instance->host_no, extended_msg[2], extended_msg[1]);
                                                tmp = 0;
                                        }
+
+                                       spin_lock_irq(&hostdata->lock);
+                                       if (!hostdata->connected)
+                                               return;
+
                                        /* Fall through to reject message */
 
                                        /* 
@@ -2109,11 +2129,11 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance) {
                                NCR5380_dprint(NDEBUG_ANY, instance);
                        }       /* switch(phase) */
                } else {
-                       spin_unlock_irq(instance->host_lock);
+                       spin_unlock_irq(&hostdata->lock);
                        NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
-                       spin_lock_irq(instance->host_lock);
+                       spin_lock_irq(&hostdata->lock);
                }
-       }                       /* while (1) */
+       }
 }
 
 /*
@@ -2309,10 +2329,12 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
        struct Scsi_Host *instance = cmd->device->host;
        struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
        struct scsi_cmnd *tmp, **prev;
+       unsigned long flags;
 
        scmd_printk(KERN_WARNING, cmd, "aborting command\n");
 
-       spin_lock_irq(instance->host_lock);
+       spin_lock_irqsave(&hostdata->lock, flags);
+
        NCR5380_print_status(instance);
 
        dprintk(NDEBUG_ABORT, "scsi%d : abort called\n", instance->host_no);
@@ -2359,7 +2381,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
                        REMOVE(5, *prev, tmp, tmp->host_scribble);
                        (*prev) = (struct scsi_cmnd *) tmp->host_scribble;
                        tmp->host_scribble = NULL;
-                       spin_unlock_irq(instance->host_lock);
+                       spin_unlock_irqrestore(&hostdata->lock, flags);
                        tmp->result = DID_ABORT << 16;
                        dprintk(NDEBUG_ABORT, "scsi%d : abort removed command from issue queue.\n", instance->host_no);
                        tmp->scsi_done(tmp);
@@ -2383,7 +2405,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
  */
 
        if (hostdata->connected) {
-               spin_unlock_irq(instance->host_lock);
+               spin_unlock_irqrestore(&hostdata->lock, flags);
                dprintk(NDEBUG_ABORT, "scsi%d : abort failed, command connected.\n", instance->host_no);
                return FAILED;
        }
@@ -2417,7 +2439,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
                        dprintk(NDEBUG_ABORT, "scsi%d : aborting disconnected command.\n", instance->host_no);
 
                        if (NCR5380_select(instance, cmd)) {
-                               spin_unlock_irq(instance->host_lock);
+                               spin_unlock_irq(&hostdata->lock);
                                return FAILED;
                        }
                        dprintk(NDEBUG_ABORT, "scsi%d : nexus reestablished.\n", instance->host_no);
@@ -2429,7 +2451,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
                                        REMOVE(5, *prev, tmp, tmp->host_scribble);
                                        *prev = (struct scsi_cmnd *) tmp->host_scribble;
                                        tmp->host_scribble = NULL;
-                                       spin_unlock_irq(instance->host_lock);
+                                       spin_unlock_irqrestore(&hostdata->lock, flags);
                                        tmp->result = DID_ABORT << 16;
                                        tmp->scsi_done(tmp);
                                        return SUCCESS;
@@ -2444,7 +2466,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
  * so we won't panic, but we will notify the user in case something really
  * broke.
  */
-       spin_unlock_irq(instance->host_lock);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
        printk(KERN_WARNING "scsi%d : warning : SCSI command probably completed successfully\n"
                        "         before abortion\n", instance->host_no);
        return FAILED;
@@ -2461,8 +2483,10 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
 static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
 {
        struct Scsi_Host *instance = cmd->device->host;
+       struct NCR5380_hostdata *hostdata = shost_priv(instance);
+       unsigned long flags;
 
-       spin_lock_irq(instance->host_lock);
+       spin_lock_irqsave(&hostdata->lock, flags);
 
 #if (NDEBUG & NDEBUG_ANY)
        scmd_printk(KERN_INFO, cmd, "performing bus reset\n");
@@ -2471,7 +2495,7 @@ static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
 
        do_reset(instance);
 
-       spin_unlock_irq(instance->host_lock);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
 
        return SUCCESS;
 }

diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
index 96fced9e606428305860b9960ec73135a055ffdc..aab360810c43a4747050039e1d925392319e621f 100644 (file)
--- a/drivers/scsi/NCR5380.h
+++ b/drivers/scsi/NCR5380.h
@@ -256,6 +256,7 @@ struct NCR5380_hostdata {
        volatile struct scsi_cmnd *connected;   /* currently connected command */
        volatile struct scsi_cmnd *issue_queue; /* waiting to be issued */
        volatile struct scsi_cmnd *disconnected_queue;  /* waiting for reconnect */
+       spinlock_t lock;                        /* protects this struct */
        int flags;
        struct scsi_eh_save ses;
        char info[256];

diff --git a/drivers/scsi/atari_NCR5380.c b/drivers/scsi/atari_NCR5380.c
index 08e8ace2681bffe89831513107591e188d971e64..2dd65cdb0930db9a3c6a07e16839195da320b1fa 100644 (file)
--- a/drivers/scsi/atari_NCR5380.c
+++ b/drivers/scsi/atari_NCR5380.c
@@ -546,15 +546,13 @@ static struct {
 static void NCR5380_print(struct Scsi_Host *instance)
 {
        unsigned char status, data, basr, mr, icr, i;
-       unsigned long flags;
 
-       local_irq_save(flags);
        data = NCR5380_read(CURRENT_SCSI_DATA_REG);
        status = NCR5380_read(STATUS_REG);
        mr = NCR5380_read(MODE_REG);
        icr = NCR5380_read(INITIATOR_COMMAND_REG);
        basr = NCR5380_read(BUS_AND_STATUS_REG);
-       local_irq_restore(flags);
+
        printk("STATUS_REG: %02x ", status);
        for (i = 0; signals[i].mask; ++i)
                if (status & signals[i].mask)
@@ -684,14 +682,12 @@ static void __maybe_unused NCR5380_print_status(struct Scsi_Host *instance)
 {
        struct NCR5380_hostdata *hostdata;
        struct scsi_cmnd *ptr;
-       unsigned long flags;
 
        NCR5380_dprint(NDEBUG_ANY, instance);
        NCR5380_dprint_phase(NDEBUG_ANY, instance);
 
        hostdata = (struct NCR5380_hostdata *)instance->hostdata;
 
-       local_irq_save(flags);
        if (!hostdata->connected)
                printk("scsi%d: no currently connected command\n", HOSTNO);
        else
@@ -704,8 +700,6 @@ static void __maybe_unused NCR5380_print_status(struct Scsi_Host *instance)
        for (ptr = (struct scsi_cmnd *) hostdata->disconnected_queue; ptr;
             ptr = NEXT(ptr))
                lprint_Scsi_Cmnd(ptr);
-
-       local_irq_restore(flags);
        printk("\n");
 }
 
@@ -732,7 +726,7 @@ static int __maybe_unused NCR5380_show_info(struct seq_file *m,
 
        hostdata = (struct NCR5380_hostdata *)instance->hostdata;
 
-       local_irq_save(flags);
+       spin_lock_irqsave(&hostdata->lock, flags);
        if (!hostdata->connected)
                seq_printf(m, "scsi%d: no currently connected command\n", HOSTNO);
        else
@@ -746,7 +740,7 @@ static int __maybe_unused NCR5380_show_info(struct seq_file *m,
             ptr = NEXT(ptr))
                show_Scsi_Cmnd(ptr, m);
 
-       local_irq_restore(flags);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
        return 0;
 }
 
@@ -784,6 +778,7 @@ static int __init NCR5380_init(struct Scsi_Host *instance, int flags)
 #if defined (REAL_DMA)
        hostdata->dma_len = 0;
 #endif
+       spin_lock_init(&hostdata->lock);
        hostdata->connected = NULL;
        hostdata->issue_queue = NULL;
        hostdata->disconnected_queue = NULL;
@@ -946,7 +941,7 @@ static int NCR5380_queue_command(struct Scsi_Host *instance,
        if (!NCR5380_acquire_dma_irq(instance))
                return SCSI_MLQUEUE_HOST_BUSY;
 
-       local_irq_save(flags);
+       spin_lock_irqsave(&hostdata->lock, flags);
 
        /*
         * Insert the cmd into the issue queue. Note that REQUEST SENSE
@@ -966,7 +961,7 @@ static int NCR5380_queue_command(struct Scsi_Host *instance,
                LIST(cmd, tmp);
                SET_NEXT(tmp, cmd);
        }
-       local_irq_restore(flags);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
 
        dprintk(NDEBUG_QUEUES, "scsi%d: command added to %s of queue\n", H_NO(cmd),
                  (cmd->cmnd[0] == REQUEST_SENSE) ? "head" : "tail");
@@ -1006,7 +1001,6 @@ static void NCR5380_main(struct work_struct *work)
        struct Scsi_Host *instance = hostdata->host;
        struct scsi_cmnd *tmp, *prev;
        int done;
-       unsigned long flags;
 
        /*
         * ++roman: Just disabling the NCR interrupt isn't sufficient here,
@@ -1014,9 +1008,8 @@ static void NCR5380_main(struct work_struct *work)
         * alter queues and touch the Falcon lock.
         */
 
-       local_save_flags(flags);
+       spin_lock_irq(&hostdata->lock);
        do {
-               local_irq_disable();    /* Freeze request queues */
                done = 1;
 
                if (!hostdata->connected) {
@@ -1043,7 +1036,6 @@ static void NCR5380_main(struct work_struct *work)
                                        tmp, scmd_id(tmp), hostdata->busy[scmd_id(tmp)],
                                        lun);
                                /*  When we find one, remove it from the issue queue. */
-                               /* ++guenther: possible race with Falcon locking */
                                if (
 #ifdef SUPPORT_TAGS
                                    !is_lun_busy( tmp, tmp->cmnd[0] != REQUEST_SENSE)
@@ -1051,8 +1043,6 @@ static void NCR5380_main(struct work_struct *work)
                                    !(hostdata->busy[tmp->device->id] & (1 << lun))
 #endif
                                    ) {
-                                       /* ++guenther: just to be sure, this must be atomic */
-                                       local_irq_disable();
                                        if (prev) {
                                                REMOVE(prev, NEXT(prev), tmp, NEXT(tmp));
                                                SET_NEXT(prev, NEXT(tmp));
@@ -1063,9 +1053,6 @@ static void NCR5380_main(struct work_struct *work)
                                        SET_NEXT(tmp, NULL);
                                        hostdata->retain_dma_intr++;
 
-                                       /* reenable interrupts after finding one */
-                                       local_irq_restore(flags);
-
                                        /*
                                         * Attempt to establish an I_T_L nexus here.
                                         * On success, instance->hostdata->connected is set.
@@ -1090,13 +1077,10 @@ static void NCR5380_main(struct work_struct *work)
 #endif
                                        if (!NCR5380_select(instance, tmp)) {
                                                /* OK or bad target */
-                                               local_irq_disable();
                                                hostdata->retain_dma_intr--;
                                                maybe_release_dma_irq(instance);
-                                               local_irq_restore(flags);
                                        } else {
                                                /* Need to retry */
-                                               local_irq_disable();
                                                LIST(tmp, hostdata->issue_queue);
                                                SET_NEXT(tmp, hostdata->issue_queue);
                                                hostdata->issue_queue = tmp;
@@ -1104,7 +1088,6 @@ static void NCR5380_main(struct work_struct *work)
                                                cmd_free_tag(tmp);
 #endif
                                                hostdata->retain_dma_intr--;
-                                               local_irq_restore(flags);
                                                done = 0;
                                                dprintk(NDEBUG_MAIN, "scsi%d: main(): select() failed, "
                                                            "returned to issue_queue\n", HOSTNO);
@@ -1120,7 +1103,6 @@ static void NCR5380_main(struct work_struct *work)
                    && !hostdata->dma_len
 #endif
                    ) {
-                       local_irq_restore(flags);
                        dprintk(NDEBUG_MAIN, "scsi%d: main: performing information transfer\n",
                                    HOSTNO);
                        NCR5380_information_transfer(instance);
@@ -1128,7 +1110,7 @@ static void NCR5380_main(struct work_struct *work)
                        done = 0;
                }
        } while (!done);
-       local_irq_restore(flags);
+       spin_unlock_irq(&hostdata->lock);
 }
 
 
@@ -1257,6 +1239,9 @@ static irqreturn_t NCR5380_intr(int irq, void *dev_id)
        struct NCR5380_hostdata *hostdata = shost_priv(instance);
        int handled = 0;
        unsigned char basr;
+       unsigned long flags;
+
+       spin_lock_irqsave(&hostdata->lock, flags);
 
        basr = NCR5380_read(BUS_AND_STATUS_REG);
        if (basr & BASR_IRQ) {
@@ -1316,6 +1301,8 @@ static irqreturn_t NCR5380_intr(int irq, void *dev_id)
 #endif
        }
 
+       spin_unlock_irqrestore(&hostdata->lock, flags);
+
        return IRQ_RETVAL(handled);
 }
 
@@ -1355,7 +1342,6 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        unsigned char *data;
        int len;
        int err;
-       unsigned long flags;
 
        NCR5380_dprint(NDEBUG_ARBITRATION, instance);
        dprintk(NDEBUG_ARBITRATION, "scsi%d: starting arbitration, id = %d\n", HOSTNO,
@@ -1366,11 +1352,6 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
         * data bus during SELECTION.
         */
 
-       local_irq_save(flags);
-       if (hostdata->connected) {
-               local_irq_restore(flags);
-               return -1;
-       }
        NCR5380_write(TARGET_COMMAND_REG, 0);
 
        /*
@@ -1384,10 +1365,11 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
         * Bus Free Delay, arbitration will begin.
         */
 
-       local_irq_restore(flags);
+       spin_unlock_irq(&hostdata->lock);
        err = NCR5380_poll_politely2(instance, MODE_REG, MR_ARBITRATE, 0,
                        INITIATOR_COMMAND_REG, ICR_ARBITRATION_PROGRESS,
                                               ICR_ARBITRATION_PROGRESS, HZ);
+       spin_lock_irq(&hostdata->lock);
        if (!(NCR5380_read(MODE_REG) & MR_ARBITRATE)) {
                /* Reselection interrupt */
                return -1;
@@ -1398,6 +1380,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
                             "select: arbitration timeout\n");
                return -1;
        }
+       spin_unlock_irq(&hostdata->lock);
 
        /* The SCSI-2 arbitration delay is 2.4 us */
        udelay(3);
@@ -1405,11 +1388,11 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        /* Check for lost arbitration */
        if ((NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) ||
            (NCR5380_read(CURRENT_SCSI_DATA_REG) & hostdata->id_higher_mask) ||
-           (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) ||
-           hostdata->connected) {
+           (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST)) {
                NCR5380_write(MODE_REG, MR_BASE);
                dprintk(NDEBUG_ARBITRATION, "scsi%d: lost arbitration, deasserting MR_ARBITRATE\n",
                           HOSTNO);
+               spin_lock_irq(&hostdata->lock);
                return -1;
        }
 
@@ -1430,6 +1413,8 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        else
                udelay(2);
 
+       spin_lock_irq(&hostdata->lock);
+
        /* NCR5380_reselect() clears MODE_REG after a reselection interrupt */
        if (!(NCR5380_read(MODE_REG) & MR_ARBITRATE))
                return -1;
@@ -1457,14 +1442,10 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
         * Reselect interrupts must be turned off prior to the dropping of BSY,
         * otherwise we will trigger an interrupt.
         */
-
-       if (hostdata->connected) {
-               NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
-               return -1;
-       }
-
        NCR5380_write(SELECT_ENABLE_REG, 0);
 
+       spin_unlock_irq(&hostdata->lock);
+
        /*
         * The initiator shall then wait at least two deskew delays and release
         * the BSY signal.
@@ -1505,6 +1486,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
                                    msecs_to_jiffies(250));
 
        if ((NCR5380_read(STATUS_REG) & (SR_SEL | SR_IO)) == (SR_SEL | SR_IO)) {
+               spin_lock_irq(&hostdata->lock);
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                NCR5380_reselect(instance);
                if (!hostdata->connected)
@@ -1515,6 +1497,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        }
 
        if (err < 0) {
+               spin_lock_irq(&hostdata->lock);
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                cmd->result = DID_BAD_TARGET << 16;
 #ifdef SUPPORT_TAGS
@@ -1554,6 +1537,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        /* Wait for start of REQ/ACK handshake */
 
        err = NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
+       spin_lock_irq(&hostdata->lock);
        if (err < 0) {
                shost_printk(KERN_ERR, instance, "select: REQ timeout\n");
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
@@ -1583,6 +1567,7 @@ static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
        NCR5380_transfer_pio(instance, &phase, &len, &data);
        dprintk(NDEBUG_SELECTION, "scsi%d: nexus established.\n", HOSTNO);
        /* XXX need to handle errors here */
+
        hostdata->connected = cmd;
 #ifndef SUPPORT_TAGS
        hostdata->busy[cmd->device->id] |= (1 << cmd->device->lun);
@@ -1849,7 +1834,6 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
        SETUP_HOSTDATA(instance);
        register int c = *count;
        register unsigned char p = *phase;
-       unsigned long flags;
 
 #if defined(CONFIG_SUN3)
        /* sanity check */
@@ -1865,7 +1849,6 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
                c, (p & SR_IO) ? "to" : "from", *data);
 
        /* netbsd turns off ints here, why not be safe and do it too */
-       local_irq_save(flags);
 
        /* send start chain */
        sun3scsi_dma_start(c, *data);
@@ -1885,8 +1868,6 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
        dregs->csr |= CSR_DMA_ENABLE;
 #endif
 
-       local_irq_restore(flags);
-
        sun3_dma_active = 1;
 
 #else /* !defined(CONFIG_SUN3) */
@@ -1913,11 +1894,9 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
                /* On the Medusa, it is a must to initialize the DMA before
                 * starting the NCR. This is also the cleaner way for the TT.
                 */
-               local_irq_save(flags);
                hostdata->dma_len = (p & SR_IO) ?
                        NCR5380_dma_read_setup(instance, d, c) :
                        NCR5380_dma_write_setup(instance, d, c);
-               local_irq_restore(flags);
        }
 
        if (p & SR_IO)
@@ -1931,11 +1910,9 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
                /* On the Falcon, the DMA setup must be done after the last */
                /* NCR access, else the DMA setup gets trashed!
                 */
-               local_irq_save(flags);
                hostdata->dma_len = (p & SR_IO) ?
                        NCR5380_dma_read_setup(instance, d, c) :
                        NCR5380_dma_write_setup(instance, d, c);
-               local_irq_restore(flags);
        }
 #endif /* !defined(CONFIG_SUN3) */
 
@@ -1963,7 +1940,6 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
 static void NCR5380_information_transfer(struct Scsi_Host *instance)
 {
        SETUP_HOSTDATA(instance);
-       unsigned long flags;
        unsigned char msgout = NOP;
        int sink = 0;
        int len;
@@ -1972,13 +1948,13 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 #endif
        unsigned char *data;
        unsigned char phase, tmp, extended_msg[10], old_phase = 0xff;
-       struct scsi_cmnd *cmd = (struct scsi_cmnd *) hostdata->connected;
+       struct scsi_cmnd *cmd;
 
 #ifdef SUN3_SCSI_VME
        dregs->csr |= CSR_INTR;
 #endif
 
-       while (1) {
+       while ((cmd = hostdata->connected)) {
                tmp = NCR5380_read(STATUS_REG);
                /* We only have a valid SCSI phase when REQ is asserted */
                if (tmp & SR_REQ) {
@@ -2112,9 +2088,13 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                        }
                                } else
 #endif /* defined(REAL_DMA) */
+                               {
+                                       spin_unlock_irq(&hostdata->lock);
                                        NCR5380_transfer_pio(instance, &phase,
                                                             (int *)&cmd->SCp.this_residual,
                                                             (unsigned char **)&cmd->SCp.ptr);
+                                       spin_lock_irq(&hostdata->lock);
+                               }
 #if defined(CONFIG_SUN3) && defined(REAL_DMA)
                                /* if we had intended to dma that command clear it */
                                if (sun3_dma_setup_done == cmd)
@@ -2124,7 +2104,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                        case PHASE_MSGIN:
                                len = 1;
                                data = &tmp;
-                               NCR5380_write(SELECT_ENABLE_REG, 0);    /* disable reselects */
                                NCR5380_transfer_pio(instance, &phase, &len, &data);
                                cmd->SCp.Message = tmp;
 
@@ -2136,7 +2115,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                        dprintk(NDEBUG_QUEUES, "scsi%d: command for target %d, lun %llu "
                                                  "completed\n", HOSTNO, cmd->device->id, cmd->device->lun);
 
-                                       local_irq_save(flags);
                                        hostdata->connected = NULL;
 #ifdef SUPPORT_TAGS
                                        cmd_free_tag(cmd);
@@ -2152,8 +2130,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 #else
                                        hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
 #endif
-                                       /* Enable reselect interrupts */
-                                       NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
 
                                        /*
                                         * I'm not sure what the correct thing to do here is :
@@ -2211,13 +2187,10 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                         * disconnected queue.
                                         */
                                        maybe_release_dma_irq(instance);
-                                       local_irq_restore(flags);
                                        return;
                                case MESSAGE_REJECT:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
-                                       /* Enable reselect interrupts */
-                                       NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        switch (hostdata->last_message) {
                                        case HEAD_OF_QUEUE_TAG:
                                        case ORDERED_QUEUE_TAG:
@@ -2241,12 +2214,10 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                case DISCONNECT:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
-                                       local_irq_save(flags);
                                        LIST(cmd,hostdata->disconnected_queue);
                                        SET_NEXT(cmd, hostdata->disconnected_queue);
                                        hostdata->connected = NULL;
                                        hostdata->disconnected_queue = cmd;
-                                       local_irq_restore(flags);
                                        dprintk(NDEBUG_QUEUES, "scsi%d: command for target %d lun %llu was "
                                                  "moved from connected to the "
                                                  "disconnected_queue\n", HOSTNO,
@@ -2277,8 +2248,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                case RESTORE_POINTERS:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
-                                       /* Enable reselect interrupts */
-                                       NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        break;
                                case EXTENDED_MESSAGE:
                                        /*
@@ -2297,6 +2266,8 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                        /* Accept first byte by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 
+                                       spin_unlock_irq(&hostdata->lock);
+
                                        dprintk(NDEBUG_EXTENDED, "scsi%d: receiving extended message\n", HOSTNO);
 
                                        len = 2;
@@ -2335,6 +2306,11 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                                           HOSTNO, extended_msg[2], extended_msg[1]);
                                                tmp = 0;
                                        }
+
+                                       spin_lock_irq(&hostdata->lock);
+                                       if (!hostdata->connected)
+                                               return;
+
                                        /* Fall through to reject message */
 
                                        /*
@@ -2367,7 +2343,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                hostdata->last_message = msgout;
                                NCR5380_transfer_pio(instance, &phase, &len, &data);
                                if (msgout == ABORT) {
-                                       local_irq_save(flags);
 #ifdef SUPPORT_TAGS
                                        cmd_free_tag(cmd);
 #else
@@ -2376,7 +2351,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                        hostdata->connected = NULL;
                                        cmd->result = DID_ERROR << 16;
                                        maybe_release_dma_irq(instance);
-                                       local_irq_restore(flags);
                                        cmd->scsi_done(cmd);
                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        return;
@@ -2404,9 +2378,11 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                NCR5380_dprint(NDEBUG_ANY, instance);
                        } /* switch(phase) */
                } else {
+                       spin_unlock_irq(&hostdata->lock);
                        NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
+                       spin_lock_irq(&hostdata->lock);
                }
-       } /* while (1) */
+       }
 }
 
 /*
@@ -2639,9 +2615,9 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
 
        scmd_printk(KERN_NOTICE, cmd, "aborting command\n");
 
-       NCR5380_print_status(instance);
+       spin_lock_irqsave(&hostdata->lock, flags);
 
-       local_irq_save(flags);
+       NCR5380_print_status(instance);
 
        dprintk(NDEBUG_ABORT, "scsi%d: abort called basr 0x%02x, sr 0x%02x\n", HOSTNO,
                    NCR5380_read(BUS_AND_STATUS_REG),
@@ -2683,11 +2659,11 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
                        hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
 #endif
                        maybe_release_dma_irq(instance);
-                       local_irq_restore(flags);
+                       spin_unlock_irqrestore(&hostdata->lock, flags);
                        cmd->scsi_done(cmd);
                        return SUCCESS;
                } else {
-                       local_irq_restore(flags);
+                       spin_unlock_irqrestore(&hostdata->lock, flags);
                        printk("scsi%d: abort of connected command failed!\n", HOSTNO);
                        return FAILED;
                }
@@ -2707,7 +2683,7 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
                        SET_NEXT(tmp, NULL);
                        tmp->result = DID_ABORT << 16;
                        maybe_release_dma_irq(instance);
-                       local_irq_restore(flags);
+                       spin_unlock_irqrestore(&hostdata->lock, flags);
                        dprintk(NDEBUG_ABORT, "scsi%d: abort removed command from issue queue.\n",
                                    HOSTNO);
                        /* Tagged queuing note: no tag to free here, hasn't been assigned
@@ -2729,7 +2705,7 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
         */
 
        if (hostdata->connected) {
-               local_irq_restore(flags);
+               spin_unlock_irqrestore(&hostdata->lock, flags);
                dprintk(NDEBUG_ABORT, "scsi%d: abort failed, command connected.\n", HOSTNO);
                return FAILED;
        }
@@ -2762,17 +2738,16 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
        for (tmp = (struct scsi_cmnd *) hostdata->disconnected_queue; tmp;
             tmp = NEXT(tmp)) {
                if (cmd == tmp) {
-                       local_irq_restore(flags);
                        dprintk(NDEBUG_ABORT, "scsi%d: aborting disconnected command.\n", HOSTNO);
 
-                       if (NCR5380_select(instance, cmd))
+                       if (NCR5380_select(instance, cmd)) {
+                               spin_unlock_irq(&hostdata->lock);
                                return FAILED;
-
+                       }
                        dprintk(NDEBUG_ABORT, "scsi%d: nexus reestablished.\n", HOSTNO);
 
                        do_abort(instance);
 
-                       local_irq_save(flags);
                        for (prev = (struct scsi_cmnd **)&(hostdata->disconnected_queue),
                             tmp = (struct scsi_cmnd *)hostdata->disconnected_queue;
                             tmp; prev = NEXTADDR(tmp), tmp = NEXT(tmp)) {
@@ -2791,7 +2766,7 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
                                        hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
 #endif
                                        maybe_release_dma_irq(instance);
-                                       local_irq_restore(flags);
+                                       spin_unlock_irqrestore(&hostdata->lock, flags);
                                        tmp->scsi_done(tmp);
                                        return SUCCESS;
                                }
@@ -2804,7 +2779,7 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
         * released after the abort, in case it is kept due to some bug.
         */
        maybe_release_dma_irq(instance);
-       local_irq_restore(flags);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
 
        /*
         * Case 5 : If we reached this point, the command was not found in any of
@@ -2836,7 +2811,7 @@ static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
        int i;
        unsigned long flags;
 
-       local_irq_save(flags);
+       spin_lock_irqsave(&hostdata->lock, flags);
 
 #if (NDEBUG & NDEBUG_ANY)
        scmd_printk(KERN_INFO, cmd, "performing bus reset\n");
@@ -2876,7 +2851,7 @@ static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
 #endif
 
        maybe_release_dma_irq(instance);
-       local_irq_restore(flags);
+       spin_unlock_irqrestore(&hostdata->lock, flags);
 
        return SUCCESS;
 }