Commit b21a4138 authored by James Bottomley's avatar James Bottomley Committed by James Bottomley

[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

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

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: default avatarJames Bottomley <>
parent f03a5670
......@@ -9200,8 +9200,8 @@ asc_prt_scsi_cmnd(struct scsi_cmnd *s)
(unsigned) s->serial_number, s->retries, s->allowed);
" timeout_per_command %d, timeout_total %d, timeout %d\n",
s->timeout_per_command, s->timeout_total, s->timeout);
" timeout_per_command %d\n",
" scsi_done 0x%lx, done 0x%lx, host_scribble 0x%lx, result 0x%x\n",
......@@ -268,6 +268,7 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int gfp_mask)
} else
cmd->jiffies_at_alloc = jiffies;
return cmd;
......@@ -798,9 +799,23 @@ static void scsi_softirq(struct softirq_action *h)
while (!list_empty(&local_q)) {
struct scsi_cmnd *cmd = list_entry(,
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;
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",
disposition = SUCCESS;
scsi_log_completion(cmd, disposition);
switch (disposition) {
......@@ -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;
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