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ieee1394: sbp2: prevent rare deadlock in shutdown

Forráskód böngészése 
Scsi_remove_device() may go into uninterruptible sleep if blocked.
Therefore sbp2_remove() unblocks the Scsi_Host before the device is
requested to be removed.  But there could be another 1394 bus reset
after that which would block the host again.  The 1394 subsystem won't
call sbp2_update() concurrently to sbp2_remove(), which is why there is
no chance for sbp2_remove() to be unblocked by sbp2_update().

The fix is to tell sbp2's bus reset handler when a device is to be shut
down so that it skips scsi_block_requests() on that host.  As before,
any new commands after a reset without reconnect will be failed quickly
by sbp2scsi_queuecommand().

In the long term, means to go without scsi_block_requests() should be
found.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter
2006-08-14 18:59:00 +02:00
szülő 902abed158
commit 2cccbb555c
2 fájl változott, egészen pontosan 19 új sor hozzáadva és 11 régi sor törölve
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21
drivers/ieee1394/sbp2.c
Fájl megtekintése

@@ -478,7 +478,7 @@ static void sbp2util_notify_fetch_agent(struct scsi_id_instance_data *scsi_id,
* There is a small window after a bus reset within which the node
* entry's generation is current but the reconnect wasn't completed.
*/
if (atomic_read(&scsi_id->unfinished_reset))
if (unlikely(atomic_read(&scsi_id->state) == SBP2LU_STATE_IN_RESET))
return;
if (hpsb_node_write(scsi_id->ne,
@@ -489,7 +489,7 @@ static void sbp2util_notify_fetch_agent(struct scsi_id_instance_data *scsi_id,
* Now accept new SCSI commands, unless a bus reset happended during
* hpsb_node_write.
*/
if (!atomic_read(&scsi_id->unfinished_reset))
if (likely(atomic_read(&scsi_id->state) != SBP2LU_STATE_IN_RESET))
scsi_unblock_requests(scsi_id->scsi_host);
}
@@ -756,7 +756,7 @@ static int sbp2_remove(struct device *dev)
sbp2scsi_complete_all_commands(scsi_id, DID_NO_CONNECT);
/* scsi_remove_device() will trigger shutdown functions of SCSI
* highlevel drivers which would deadlock if blocked. */
atomic_set(&scsi_id->unfinished_reset, 0);
atomic_set(&scsi_id->state, SBP2LU_STATE_IN_SHUTDOWN);
scsi_unblock_requests(scsi_id->scsi_host);
}
sdev = scsi_id->sdev;
@@ -811,7 +811,7 @@ static int sbp2_update(struct unit_directory *ud)
/* Accept new commands unless there was another bus reset in the
* meantime. */
if (hpsb_node_entry_valid(scsi_id->ne)) {
atomic_set(&scsi_id->unfinished_reset, 0);
atomic_set(&scsi_id->state, SBP2LU_STATE_RUNNING);
scsi_unblock_requests(scsi_id->scsi_host);
}
return 0;
@@ -842,7 +842,7 @@ static struct scsi_id_instance_data *sbp2_alloc_device(struct unit_directory *ud
INIT_LIST_HEAD(&scsi_id->sbp2_command_orb_completed);
INIT_LIST_HEAD(&scsi_id->scsi_list);
spin_lock_init(&scsi_id->sbp2_command_orb_lock);
atomic_set(&scsi_id->unfinished_reset, 0);
atomic_set(&scsi_id->state, SBP2LU_STATE_RUNNING);
INIT_WORK(&scsi_id->protocol_work, NULL, NULL);
ud->device.driver_data = scsi_id;
@@ -926,13 +926,14 @@ static void sbp2_host_reset(struct hpsb_host *host)
struct scsi_id_instance_data *scsi_id;
hi = hpsb_get_hostinfo(&sbp2_highlevel, host);
if (hi) {
list_for_each_entry(scsi_id, &hi->scsi_ids, scsi_list) {
atomic_set(&scsi_id->unfinished_reset, 1);
if (!hi)
return;
list_for_each_entry(scsi_id, &hi->scsi_ids, scsi_list)
if (likely(atomic_read(&scsi_id->state) !=
SBP2LU_STATE_IN_SHUTDOWN)) {
atomic_set(&scsi_id->state, SBP2LU_STATE_IN_RESET);
scsi_block_requests(scsi_id->scsi_host);
}
}
}
/*