ide: fix ->io_32bit race in ide_taskfile_ioctl()

In ide_taskfile_ioctl(), there was a race condition involving
drive->io_32bit.  It was cleared and restored during ioctl
requests but there was no synchronization with other requests.
So, other requests could execute with the altered ->io_32bit
setting or updated drive->io_32bit could be overwritten by
ide_taskfile_ioctl().

This patch adds IDE_TFLAG_IO_16BIT flag to indicate to
ide_pio_datablock() that 16-bit I/O is needed regardless of
drive->io_32bit settting.

Bart:
- ported it over recent IDE changes

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index 3ecafab8f54e..b72a9aea7a51 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -346,9 +346,18 @@ static void ide_pio_multi(ide_drive_t *drive, unsigned int write)
 static void ide_pio_datablock(ide_drive_t *drive, struct request *rq,
                                      unsigned int write)
 {
+        u8 saved_io_32bit = drive->io_32bit;
+
         if (rq->bio)    /* fs request */
                 rq->errors = 0;
 
+        if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
+                ide_task_t *task = rq->special;
+
+                if (task->tf_flags & IDE_TFLAG_IO_16BIT)
+                        drive->io_32bit = 0;
+        }
+
         touch_softlockup_watchdog();
 
         switch (drive->hwif->data_phase) {
@@ -360,6 +369,8 @@ static void ide_pio_datablock(ide_drive_t *drive, struct request *rq,
                 ide_pio_sector(drive, write);
                 break;
         }
+
+        drive->io_32bit = saved_io_32bit;
 }
 
 static ide_startstop_t task_error(ide_drive_t *drive, struct request *rq,
@@ -555,7 +566,6 @@ int ide_taskfile_ioctl (ide_drive_t *drive, unsigned int cmd, unsigned long arg)
         unsigned int taskin     = 0;
         unsigned int taskout    = 0;
         u16 nsect               = 0;
-        u8 io_32bit             = drive->io_32bit;
         char __user *buf = (char __user *)arg;
 
 //      printk("IDE Taskfile ...\n");
@@ -608,7 +618,7 @@ int ide_taskfile_ioctl (ide_drive_t *drive, unsigned int cmd, unsigned long arg)
 
         args.data_phase = req_task->data_phase;
 
-        args.tf_flags = IDE_TFLAG_OUT_DEVICE;
+        args.tf_flags = IDE_TFLAG_IO_16BIT | IDE_TFLAG_OUT_DEVICE;
         if (drive->addressing == 1)
                 args.tf_flags |= IDE_TFLAG_LBA48;
 
@@ -646,7 +656,6 @@ int ide_taskfile_ioctl (ide_drive_t *drive, unsigned int cmd, unsigned long arg)
         if (req_task->in_flags.b.data)
                 args.tf_flags |= IDE_TFLAG_IN_DATA;
 
-        drive->io_32bit = 0;
         switch(req_task->data_phase) {
                 case TASKFILE_MULTI_OUT:
                         if (!drive->mult_count) {
@@ -742,8 +751,6 @@ abort:
 
 //      printk("IDE Taskfile ioctl ended. rc = %i\n", err);
 
-        drive->io_32bit = io_32bit;
-
         return err;
 }
 #endif