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atari_scsi: Fix atari_scsi deadlocks on Falcon

Telusuri Sumber 
Don't disable irqs when waiting for the ST DMA "lock"; its release may
require an interrupt.

Introduce stdma_try_lock() for use in soft irq context. atari_scsi now tells
the SCSI mid-layer to defer queueing a command if the ST DMA lock is not
available, as per Michael's patch:
http://marc.info/?l=linux-m68k&m=139095335824863&w=2

The falcon_got_lock variable is race prone: we can't disable IRQs while
waiting to acquire the lock, so after acquiring it there must be some
interval during which falcon_got_lock remains false. Introduce
stdma_is_locked_by() to replace falcon_got_lock.

The falcon_got_lock tests in the EH handlers are incorrect these days. It
can happen that an EH handler is called after a command completes normally.
Remove these checks along with falcon_got_lock.

Also remove the complicated and racy fairness wait queues. If fairness is an
issue (when SCSI competes with IDE for the ST DMA interrupt), the solution
is likely to be a lower value for host->can_queue.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Finn Thain
2014-11-12 16:12:08 +11:00
committed by Christoph Hellwig
orang tua cbad48deb3
melakukan 16b29e75a7
4 mengubah file dengan 66 tambahan dan 107 penghapusan
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33
drivers/scsi/atari_NCR5380.c
Melihat File

@@ -879,10 +879,10 @@ static void NCR5380_exit(struct Scsi_Host *instance)
*
*/
static int NCR5380_queue_command_lck(struct scsi_cmnd *cmd,
void (*done)(struct scsi_cmnd *))
static int NCR5380_queue_command(struct Scsi_Host *instance,
struct scsi_cmnd *cmd)
{
SETUP_HOSTDATA(cmd->device->host);
struct NCR5380_hostdata *hostdata = shost_priv(instance);
struct scsi_cmnd *tmp;
unsigned long flags;
@@ -893,7 +893,7 @@ static int NCR5380_queue_command_lck(struct scsi_cmnd *cmd,
printk(KERN_NOTICE "scsi%d: WRITE attempted with NO_WRITE debugging flag set\n",
H_NO(cmd));
cmd->result = (DID_ERROR << 16);
done(cmd);
cmd->scsi_done(cmd);
return 0;
}
#endif /* (NDEBUG & NDEBUG_NO_WRITE) */
@@ -904,8 +904,6 @@ static int NCR5380_queue_command_lck(struct scsi_cmnd *cmd,
*/
SET_NEXT(cmd, NULL);
cmd->scsi_done = done;
cmd->result = 0;
/*
@@ -915,7 +913,6 @@ static int NCR5380_queue_command_lck(struct scsi_cmnd *cmd,
* sense data is only guaranteed to be valid while the condition exists.
*/
local_irq_save(flags);
/* ++guenther: now that the issue queue is being set up, we can lock ST-DMA.
* Otherwise a running NCR5380_main may steal the lock.
* Lock before actually inserting due to fairness reasons explained in
@@ -928,11 +925,11 @@ static int NCR5380_queue_command_lck(struct scsi_cmnd *cmd,
* because also a timer int can trigger an abort or reset, which would
* alter queues and touch the lock.
*/
if (!IS_A_TT()) {
/* perhaps stop command timer here */
falcon_get_lock();
/* perhaps restart command timer here */
}
if (!falcon_get_lock())
return SCSI_MLQUEUE_HOST_BUSY;
local_irq_save(flags);
if (!(hostdata->issue_queue) || (cmd->cmnd[0] == REQUEST_SENSE)) {
LIST(cmd, hostdata->issue_queue);
SET_NEXT(cmd, hostdata->issue_queue);
@@ -956,15 +953,13 @@ static int NCR5380_queue_command_lck(struct scsi_cmnd *cmd,
* If we're not in an interrupt, we can call NCR5380_main()
* unconditionally, because it cannot be already running.
*/
if (in_interrupt() || ((flags >> 8) & 7) >= 6)
if (in_interrupt() || irqs_disabled())
queue_main();
else
NCR5380_main(NULL);
return 0;
}
static DEF_SCSI_QCMD(NCR5380_queue_command)
/*
* Function : NCR5380_main (void)
*
@@ -2554,10 +2549,6 @@ int NCR5380_abort(struct scsi_cmnd *cmd)
local_irq_save(flags);
if (!IS_A_TT() && !falcon_got_lock)
printk(KERN_ERR "scsi%d: !!BINGO!! Falcon has no lock in NCR5380_abort\n",
HOSTNO);
dprintk(NDEBUG_ABORT, "scsi%d: abort called basr 0x%02x, sr 0x%02x\n", HOSTNO,
NCR5380_read(BUS_AND_STATUS_REG),
NCR5380_read(STATUS_REG));
@@ -2756,10 +2747,6 @@ static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
struct scsi_cmnd *connected, *disconnected_queue;
#endif
if (!IS_A_TT() && !falcon_got_lock)
printk(KERN_ERR "scsi%d: !!BINGO!! Falcon has no lock in NCR5380_reset\n",
H_NO(cmd));
NCR5380_print_status(cmd->device->host);
/* get in phase */