[SCSI] add global timeout to the scsi mid-layer

There are certain rogue devices (and the aic7xxx driver) that return
BUSY or QUEUE_FULL forever.  This code will apply a global timeout (of
the total number of retries times the per command timer) to a given
command.  If it is exceeded, the command is completed regardless of its
state.

The patch also removes the unused field in the command: timeout and
timeout_total.

This solves the problem of detecting an endless loop in the mid-layer
because of BUSY/QUEUE_FULL bouncing, but will not recover the device.
In the aic7xxx case, the driver can be recovered by sending a bus reset,
so possibly this should be tied into the error handler?

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 9957f16dcc5d..bed4b7c9be99 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -51,12 +51,16 @@ struct scsi_cmnd {
          * printk's to use ->pid, so that we can kill this field.
          */
         unsigned long serial_number;
+        /*
+         * This is set to jiffies as it was when the command was first
+         * allocated.  It is used to time how long the command has
+         * been outstanding
+         */
+        unsigned long jiffies_at_alloc;
 
         int retries;
         int allowed;
         int timeout_per_command;
-        int timeout_total;
-        int timeout;
 
         unsigned char cmd_len;
         unsigned char old_cmd_len;