[PATCH AUTOSEL 5.4 059/130] scsi: atari_scsi: Fix race condition between .queuecommand and EH

Sasha Levin
2020-12-23T02:20:35Z

From: Finn Thain <fthain@telegraphics.com.au>

[ Upstream commit 03fe6a640a05c5dc04b6bcdddfb981d015e84ed4 ]

It is possible that bus_reset_cleanup() or .eh_abort_handler could be
invoked during NCR5380_queuecommand(). If that takes place before the new
command is enqueued and after the ST-DMA "lock" has been acquired, the
ST-DMA "lock" will be released again. This will result in a lost DMA
interrupt and a command timeout. Fix this by excluding EH and interrupt
handlers while the new command is enqueued.

Link: https://lore.kernel.org/r/af25163257796b50bb99d4ede4025cea55787b8f.1605847196.git.fthain@telegraphics.com.au
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/NCR5380.c | 9 ++++++---
drivers/scsi/atari_scsi.c | 10 +++-------
2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index d4401c768a0c7..5db10a16a743a 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -567,11 +567,14 @@ static int NCR5380_queue_command(struct Scsi_Host *instance,

cmd->result = 0;

- if (!NCR5380_acquire_dma_irq(instance))
- return SCSI_MLQUEUE_HOST_BUSY;
-
spin_lock_irqsave(&hostdata->lock, flags);

+ if (!NCR5380_acquire_dma_irq(instance)) {
+ spin_unlock_irqrestore(&hostdata->lock, flags);
+
+ return SCSI_MLQUEUE_HOST_BUSY;
+ }
+
/*
* Insert the cmd into the issue queue. Note that REQUEST SENSE
* commands are added to the head of the queue since any command will
diff --git a/drivers/scsi/atari_scsi.c b/drivers/scsi/atari_scsi.c
index a82b63a666356..95d7a35860836 100644
--- a/drivers/scsi/atari_scsi.c
+++ b/drivers/scsi/atari_scsi.c
@@ -376,15 +376,11 @@ static int falcon_get_lock(struct Scsi_Host *instance)
if (IS_A_TT())
return 1;

- if (stdma_is_locked_by(scsi_falcon_intr) &&
- instance->hostt->can_queue > 1)
+ if (stdma_is_locked_by(scsi_falcon_intr))
return 1;

- if (in_interrupt())
- return stdma_try_lock(scsi_falcon_intr, instance);
-
- stdma_lock(scsi_falcon_intr, instance);
- return 1;
+ /* stdma_lock() may sleep which means it can't be used here */
+ return stdma_try_lock(scsi_falcon_intr, instance);
}

#ifndef MODULE
--
2.27.0