ide: fix races in handling of user-space SET XFER commands

* Make cmd->tf_flags field 'u16' and add IDE_TFLAG_SET_XFER taskfile flag.

* Update ide_finish_cmd() to set xfer / re-read id if the new flag is set.

* Convert set_xfer_rate() (write handler for /proc/ide/hd?/current_speed)
  and ide_cmd_ioctl() (HDIO_DRIVE_CMD ioctl handler) to use the new flag.

* Remove no longer needed disable_irq_nosync() + enable_irq() from
  ide_config_drive_speed().

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 14 insertions, 26 deletions

diff --git a/drivers/ide/ide-ioctls.c b/drivers/ide/ide-ioctls.c
index e246d3d3fbcc..d3440b5010a5 100644
--- a/drivers/ide/ide-ioctls.c
+++ b/drivers/ide/ide-ioctls.c
@@ -167,6 +167,8 @@ static int ide_cmd_ioctl(ide_drive_t *drive, unsigned long arg)
                         err = -EINVAL;
                         goto abort;
                 }
+
+                cmd.tf_flags |= IDE_TFLAG_SET_XFER;
         }
 
         err = ide_raw_taskfile(drive, &cmd, buf, args[3]);
@@ -174,12 +176,6 @@ static int ide_cmd_ioctl(ide_drive_t *drive, unsigned long arg)
         args[0] = tf->status;
         args[1] = tf->error;
         args[2] = tf->nsect;
-
-        if (!err && xfer_rate) {
-                /* active-retuning-calls future */
-                ide_set_xfer_rate(drive, xfer_rate);
-                ide_driveid_update(drive);
-        }
 abort:
         if (copy_to_user((void __user *)arg, &args, 4))
                 err = -EFAULT;
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index b99873845d21..b14fa9a87c49 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -363,14 +363,6 @@ int ide_config_drive_speed(ide_drive_t *drive, u8 speed)
          * this point (lost interrupt).
          */
 
-        /*
-         *      FIXME: we race against the running IRQ here if
-         *      this is called from non IRQ context. If we use
-         *      disable_irq() we hang on the error path. Work
-         *      is needed.
-         */
-        disable_irq_nosync(hwif->irq);
-
         udelay(1);
         tp_ops->dev_select(drive);
         SELECT_MASK(drive, 1);
@@ -394,8 +386,6 @@ int ide_config_drive_speed(ide_drive_t *drive, u8 speed)
 
         SELECT_MASK(drive, 0);
 
-        enable_irq(hwif->irq);
-
         if (error) {
                 (void) ide_dump_status(drive, "set_drive_speed_status", stat);
                 return error;
diff --git a/drivers/ide/ide-proc.c b/drivers/ide/ide-proc.c
index 3242698832a4..021de41655e6 100644
--- a/drivers/ide/ide-proc.c
+++ b/drivers/ide/ide-proc.c
@@ -195,7 +195,6 @@ ide_devset_get(xfer_rate, current_speed);
 static int set_xfer_rate (ide_drive_t *drive, int arg)
 {
         struct ide_cmd cmd;
-        int err;
 
         if (arg < XFER_PIO_0 || arg > XFER_UDMA_6)
                 return -EINVAL;
@@ -206,14 +205,9 @@ static int set_xfer_rate (ide_drive_t *drive, int arg)
         cmd.tf.nsect   = (u8)arg;
         cmd.valid.out.tf = IDE_VALID_FEATURE | IDE_VALID_NSECT;
         cmd.valid.in.tf  = IDE_VALID_NSECT;
+        cmd.tf_flags   = IDE_TFLAG_SET_XFER;
 
-        err = ide_no_data_taskfile(drive, &cmd);
-
-        if (!err) {
-                ide_set_xfer_rate(drive, (u8) arg);
-                ide_driveid_update(drive);
-        }
-        return err;
+        return ide_no_data_taskfile(drive, &cmd);
 }
 
 ide_devset_rw(current_speed, xfer_rate);
diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index 50336d51eebc..cc8633cbe133 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -324,10 +324,17 @@ static void ide_error_cmd(ide_drive_t *drive, struct ide_cmd *cmd)
 void ide_finish_cmd(ide_drive_t *drive, struct ide_cmd *cmd, u8 stat)
 {
         struct request *rq = drive->hwif->rq;
-        u8 err = ide_read_error(drive);
+        u8 err = ide_read_error(drive), nsect = cmd->tf.nsect;
+        u8 set_xfer = !!(cmd->tf_flags & IDE_TFLAG_SET_XFER);
 
         ide_complete_cmd(drive, cmd, stat, err);
         rq->errors = err;
+
+        if (err == 0 && set_xfer) {
+                ide_set_xfer_rate(drive, nsect);
+                ide_driveid_update(drive);
+        }
+
         ide_complete_rq(drive, err ? -EIO : 0, blk_rq_bytes(rq));
 }
 
diff --git a/include/linux/ide.h b/include/linux/ide.h
index cb6cd0459a5e..803c1ae31237 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -258,6 +258,7 @@ enum {
         IDE_TFLAG_DYN                   = (1 << 5),
         IDE_TFLAG_FS                    = (1 << 6),
         IDE_TFLAG_MULTI_PIO             = (1 << 7),
+        IDE_TFLAG_SET_XFER              = (1 << 8),
 };
 
 enum {
@@ -294,7 +295,7 @@ struct ide_cmd {
                 } out, in;
         } valid;
 
-        u8                      tf_flags;
+        u16                     tf_flags;
         u8                      ftf_flags;      /* for TASKFILE ioctl */
         int                     protocol;