ide: ensure atapi sense request aren't preempted

There's an issue with how sense requests are handled in IDE. If ide-cd
encounters an error, it queues a sense request. With how IDE request
handling is done, this is the next request we need to handle. But it's
impossible to guarantee this, as another request could come in between
the sense being queued, and ->queue_rq() being run and handling it. If
that request ALSO fails, then we attempt to doubly queue the single
sense request we have.

Since we only support one active request at the time, defer request
processing when a sense request is queued.

Fixes: 600335205b8d "ide: convert to blk-mq"
Reported-by: He Zhe <zhe.he@windriver.com>
Tested-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c
index da58020a144e..33a28cde126c 100644
--- a/drivers/ide/ide-atapi.c
+++ b/drivers/ide/ide-atapi.c
@@ -235,21 +235,28 @@ EXPORT_SYMBOL_GPL(ide_prep_sense);
 
 int ide_queue_sense_rq(ide_drive_t *drive, void *special)
 {
-        struct request *sense_rq = drive->sense_rq;
+        ide_hwif_t *hwif = drive->hwif;
+        struct request *sense_rq;
+        unsigned long flags;
+
+        spin_lock_irqsave(&hwif->lock, flags);
 
         /* deferred failure from ide_prep_sense() */
         if (!drive->sense_rq_armed) {
                 printk(KERN_WARNING PFX "%s: error queuing a sense request\n",
                        drive->name);
+                spin_unlock_irqrestore(&hwif->lock, flags);
                 return -ENOMEM;
         }
 
+        sense_rq = drive->sense_rq;
         ide_req(sense_rq)->special = special;
         drive->sense_rq_armed = false;
 
         drive->hwif->rq = NULL;
 
         ide_insert_request_head(drive, sense_rq);
+        spin_unlock_irqrestore(&hwif->lock, flags);
         return 0;
 }
 EXPORT_SYMBOL_GPL(ide_queue_sense_rq);