ncr5380: Dont release lock for PIO transfer

The calls to NCR5380_transfer_pio() for DATA IN and DATA OUT phases will
modify cmd->SCp.this_residual, cmd->SCp.ptr and cmd->SCp.buffer. That
works as long as EH does not intervene, which became possible in
atari_NCR5380.c when I changed the locking to bring it closer to
NCR5380.c.

If error recovery aborts the command, the scsi_cmnd in question and its
buffer will be returned to the mid-layer. So the transfer has to cease,
but it can't be stopped by the initiator because the target controls the
bus phase.

The problem does not arise if the lock is not released. That was fine for
atari_scsi, because it implements DMA. For the other drivers, we have to
release the lock and re-enable interrupts for long PIO data transfers.

The solution is to split the transfer into small chunks. In between chunks
the main loop releases the lock and re-enables interrupts. Thus interrupts
can be serviced and eh_bus_reset_handler can intervene if need be.

This fixes an oops in NCR5380_transfer_pio() that can happen when the EH
abort handler is invoked during DATA IN or DATA OUT phase.

Fixes: 11d2f63b9cf5 ("ncr5380: Change instance->host_lock to hostdata->lock")
Reported-and-tested-by: Michael Schmitz <schmitzmic@gmail.com>
Cc: <stable@vger.kernel.org> # 4.5
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index ce577f41332883823296ddfed94b0dd7ab119e8e..0e00d487ceb48fcb004256d07ac53afae595b26e 100644 (file)
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -1759,9 +1759,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
        unsigned char msgout = NOP;
        int sink = 0;
        int len;
-#if defined(PSEUDO_DMA) || defined(REAL_DMA_POLL)
        int transfersize;
-#endif
        unsigned char *data;
        unsigned char phase, tmp, extended_msg[10], old_phase = 0xff;
        struct scsi_cmnd *cmd;
@@ -1854,13 +1852,17 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
                                } else
 #endif                         /* defined(PSEUDO_DMA) || defined(REAL_DMA_POLL) */
                                {
-                                       spin_unlock_irq(&hostdata->lock);
-                                       NCR5380_transfer_pio(instance, &phase,
-                                                            (int *)&cmd->SCp.this_residual,
+                                       /* Break up transfer into 3 ms chunks,
+                                        * presuming 6 accesses per handshake.
+                                        */
+                                       transfersize = min((unsigned long)cmd->SCp.this_residual,
+                                                          hostdata->accesses_per_ms / 2);
+                                       len = transfersize;
+                                       NCR5380_transfer_pio(instance, &phase, &len,
                                                             (unsigned char **)&cmd->SCp.ptr);
-                                       spin_lock_irq(&hostdata->lock);
+                                       cmd->SCp.this_residual -= transfersize - len;
                                }
-                               break;
+                               return;
                        case PHASE_MSGIN:
                                len = 1;
                                data = &tmp;

diff --git a/drivers/scsi/atari_NCR5380.c b/drivers/scsi/atari_NCR5380.c
index af04218297012f99e52fbcc80b5679bf9bf49627..d382e71f4f4e00c4a2481b3e00f70f52cff2b8bc 100644 (file)
--- a/drivers/scsi/atari_NCR5380.c
+++ b/drivers/scsi/atari_NCR5380.c
@@ -1838,9 +1838,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
        unsigned char msgout = NOP;
        int sink = 0;
        int len;
-#if defined(REAL_DMA)
        int transfersize;
-#endif
        unsigned char *data;
        unsigned char phase, tmp, extended_msg[10], old_phase = 0xff;
        struct scsi_cmnd *cmd;
@@ -1983,18 +1981,22 @@ 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,
+                                       /* Break up transfer into 3 ms chunks,
+                                        * presuming 6 accesses per handshake.
+                                        */
+                                       transfersize = min((unsigned long)cmd->SCp.this_residual,
+                                                          hostdata->accesses_per_ms / 2);
+                                       len = transfersize;
+                                       NCR5380_transfer_pio(instance, &phase, &len,
                                                             (unsigned char **)&cmd->SCp.ptr);
-                                       spin_lock_irq(&hostdata->lock);
+                                       cmd->SCp.this_residual -= transfersize - len;
                                }
 #if defined(CONFIG_SUN3) && defined(REAL_DMA)
                                /* if we had intended to dma that command clear it */
                                if (sun3_dma_setup_done == cmd)
                                        sun3_dma_setup_done = NULL;
 #endif
-                               break;
+                               return;
                        case PHASE_MSGIN:
                                len = 1;
                                data = &tmp;