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[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>
This commit is contained in:
James Bottomley 2005-08-05 21:45:40 -05:00 committed by James Bottomley
parent f03a567054
commit b21a413851
3 changed files with 23 additions and 4 deletions
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4
drivers/scsi/advansys.c
View File

@ -9200,8 +9200,8 @@ asc_prt_scsi_cmnd(struct scsi_cmnd *s)
(unsigned) s->serial_number, s->retries, s->allowed);
printk(
" timeout_per_command %d, timeout_total %d, timeout %d\n",
s->timeout_per_command, s->timeout_total, s->timeout);
" timeout_per_command %d\n",
s->timeout_per_command);
printk(
" scsi_done 0x%lx, done 0x%lx, host_scribble 0x%lx, result 0x%x\n",

15
drivers/scsi/scsi.c
View File

@ -268,6 +268,7 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int gfp_mask)
} else
put_device(&dev->sdev_gendev);
cmd->jiffies_at_alloc = jiffies;
return cmd;
}
EXPORT_SYMBOL(scsi_get_command);
@ -798,9 +799,23 @@ static void scsi_softirq(struct softirq_action *h)
while (!list_empty(&local_q)) {
struct scsi_cmnd *cmd = list_entry(local_q.next,
struct scsi_cmnd, eh_entry);
/* The longest time any command should be outstanding is the
* per command timeout multiplied by the number of retries.
*
* For a typical command, this is 2.5 minutes */
unsigned long wait_for
= cmd->allowed * cmd->timeout_per_command;
list_del_init(&cmd->eh_entry);
disposition = scsi_decide_disposition(cmd);
if (disposition != SUCCESS &&
time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
dev_printk(KERN_ERR, &cmd->device->sdev_gendev,
"timing out command, waited %ds\n",
wait_for/HZ);
disposition = SUCCESS;
}
scsi_log_completion(cmd, disposition);
switch (disposition) {
case SUCCESS:

8
include/scsi/scsi_cmnd.h
View File

@ -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;