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  1. 18 2月, 2010 1 次提交
    • M
      [SCSI] libiscsi: reset cmd timer if cmds are making progress · 92ed4d69
      由 Mike Christie 提交于 
      This patch resets the cmd timer if cmds started before
the timedout command are making progress. The idea is
that the cmd probably timed out because we are trying
to exeucte too many commands. If it turns out that the
device the IO timedout on was bad or the cmd just got
screwed up but other IO/devs were ok then we will
will figure this out when the cmds ahead of the timed
out one complete ok.

This also fixes a bug where we were sort of detecting
this by setting the last_timeout and last_xfer to the
same value when the task was allocated. That caught
the case where we never got to send any IO for it. However,
if the problem had started right before we started the
new task, then we were forced to wait an extra cmd
timeout seconds to start the scsi eh.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>
      92ed4d69
  3. 23 12月, 2009 4 次提交
  5. 05 12月, 2009 5 次提交
  7. 03 10月, 2009 1 次提交
  9. 12 9月, 2009 2 次提交
  11. 05 9月, 2009 3 次提交
  13. 30 7月, 2009 1 次提交
  15. 21 6月, 2009 2 次提交
  17. 24 5月, 2009 11 次提交
  19. 27 4月, 2009 1 次提交
  21. 03 4月, 2009 1 次提交
    • J
      [SCSI] libiscsi: fix iscsi pool error path · fd6e1c14
      由 Jean Delvare 提交于 
      Le lundi 30 mars 2009, Chris Wright a écrit :
> q->queue could be ERR_PTR(-ENOMEM) which will break unwinding
> on error.  Make iscsi_pool_free more defensive.
>

Making the freeing of q->queue dependent on q->pool being set looks
really weird (although it is correct at the moment. But this seems
to be fixable in a much simpler way.

With the benefit that only the error case is slowed down. In both
cases we have a problem if q->queue contains an error value but it's
not -ENOMEM. Apparently this can't happen today, but it doesn't feel
right to assume this will always be true. Maybe it's the right time
to fix this as well.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
      fd6e1c14
  23. 14 3月, 2009 7 次提交
  25. 11 2月, 2009 1 次提交
    • M
      [SCSI] libiscsi: Fix scsi command timeout oops in iscsi_eh_timed_out · 308cec14
      由 Mike Christie 提交于 
      Yanling Qi from LSI found the root cause of the panic, below is his
analysis:

Problem description: the open iscsi driver installs eh_timed_out handler
to the
blank_transport_template of the scsi middle level that causes panic of
timed
out command of other host

Here are the details

Iscsi Session creation

During iscsi session creation time, the iscsi_tcp_session_create() of
iscsi_tpc.c will create a scsi-host for the session. See the statement
marked
with the label A. The statement B replaces the shost->transportt point
with a
local struct variable.

static struct iscsi_cls_session *
iscsi_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
                         uint16_t qdepth, uint32_t initial_cmdsn,
                         uint32_t *hostno)
{
        struct iscsi_cls_session *cls_session;
        struct iscsi_session *session;
        struct Scsi_Host *shost;
        int cmd_i;
        if (ep) {
                printk(KERN_ERR "iscsi_tcp: invalid ep %p.\n", ep);
                return NULL;
        }

A        shost = iscsi_host_alloc(&iscsi_sht, 0, qdepth);

        if (!shost)

                return NULL;

B         shost->transportt = iscsi_tcp_scsi_transport;

        shost->max_lun = iscsi_max_lun;

Please note the scsi host is allocated by invoking isccsi_host_alloc()
in
libiscsi.c

Polluting the middle level blank_transport_template in
iscsi_host_alloc() of
libiscsi.c

The iscsi_host_alloc() invokes the middle level function
scsi_host_alloc() in
hosts.c for allocating a scsi_host. Then the statement marked with C
assigns
the iscsi_eh_cmd_timed_out handler to the eh_timed_out callback
function.

struct Scsi_Host *iscsi_host_alloc(struct scsi_host_template *sht,

                                   int dd_data_size, uint16_t qdepth)

{
        struct Scsi_Host *shost;
        struct iscsi_host *ihost;
        shost = scsi_host_alloc(sht, sizeof(struct iscsi_host) +
dd_data_size);
        if (!shost)
                return NULL;

 C      shost->transportt->eh_timed_out = iscsi_eh_cmd_timed_out;

Please note the shost->transport is the middle level
blank_transport_template
as shown in the code segment below. We see two problems here. 1.
iscsi_eh_cmd_timed_out is installed to the blank_transport_template that
will
cause some body else problem. 2. iscsi_eh_cmd_timed_out will never be
invoked
when iscsi command gets timeout because the statement B resets the
pointer.

Middle level blank_transport_template

In the middle level function scsi_host_alloc() of hosts.c, the middle
level
assigns a blank_transport_template for those hosts not implementing its
transport layer. All HBAs without supporting a specific scsi_transport
will
share the middle level blank_transport_template. Please see the
statement D

struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int
privsize)

{
        struct Scsi_Host *shost;
        gfp_t gfp_mask = GFP_KERNEL;
        int rval;
        if (sht->unchecked_isa_dma && privsize)
                gfp_mask |= __GFP_DMA;

         shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
        if (!shost)
                return NULL;

        shost->host_lock = &shost->default_lock;

        spin_lock_init(shost->host_lock);

        shost->shost_state = SHOST_CREATED;

        INIT_LIST_HEAD(&shost->__devices);

        INIT_LIST_HEAD(&shost->__targets);

        INIT_LIST_HEAD(&shost->eh_cmd_q);

        INIT_LIST_HEAD(&shost->starved_list);

        init_waitqueue_head(&shost->host_wait);

        mutex_init(&shost->scan_mutex);

        shost->host_no = scsi_host_next_hn++; /* XXX(hch): still racy */

        shost->dma_channel = 0xff;

        /* These three are default values which can be overridden */

        shost->max_channel = 0;

        shost->max_id = 8;

        shost->max_lun = 8;

        /* Give each shost a default transportt */

 D       shost->transportt = &blank_transport_template;

Why we see panic at iscsi_eh_cmd_timed_out()

The mpp virtual HBA doesn’t have a specific scsi_transport. Therefore,
the
blank_transport_template will be assigned to the virtual host of the MPP
virtual HBA by SCSI middle level. Please note that the statement C has
assigned
iscsi-transport eh_timedout handler to the blank_transport_template.
When a mpp
virtual command gets timedout, the iscsi_eh_cmd_timed_out() will be
invoked to
handle mpp virtual command timeout from the middle level
scsi_times_out()
function of the scsi_error.c.

enum blk_eh_timer_return scsi_times_out(struct request *req)

{

        struct scsi_cmnd *scmd = req->special;

        enum blk_eh_timer_return (*eh_timed_out)(struct scsi_cmnd *);

        enum blk_eh_timer_return rtn = BLK_EH_NOT_HANDLED;

        scsi_log_completion(scmd, TIMEOUT_ERROR);

        if (scmd->device->host->transportt->eh_timed_out)

 E               eh_timed_out =
scmd->device->host->transportt->eh_timed_out;

        else if (scmd->device->host->hostt->eh_timed_out)

                eh_timed_out = scmd->device->host->hostt->eh_timed_out;

        else

                eh_timed_out = NULL;

        if (eh_timed_out) {

                rtn = eh_timed_out(scmd);

It is very easy to understand why we get panic in the
iscsi_eh_cmd_timed_out().
A scsi_cmnd from a no-iscsi device definitely can not resolve out a
session and
session->lock. The panic can be happed anywhere during the differencing.

static enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd
*scmd)

{

        struct iscsi_cls_session *cls_session;

        struct iscsi_session *session;

        struct iscsi_conn *conn;

        enum blk_eh_timer_return rc = BLK_EH_NOT_HANDLED;

        cls_session = starget_to_session(scsi_target(scmd->device));

        session = cls_session->dd_data;

        debug_scsi("scsi cmd %p timedout\n", scmd);

        spin_lock(&session->lock);

This patch fixes the problem by moving the setting of the
iscsi_eh_cmd_timed_out to iscsi_add_host, which is after the LLDs
have set their transport template to shost->transportt.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
      308cec14