Re: [PATCH v1] mpt3sas: Use driver scsi lookup to track outstanding IOs

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On 2/26/19 12:48 PM, Sreekanth Reddy wrote:
On Tue, Feb 26, 2019 at 12:38 AM Hannes Reinecke <hare@xxxxxxx> wrote:

On 2/21/19 1:11 PM, Sreekanth Reddy wrote:
During expander reset handling, the driver invokes kernel function
scsi_host_find_tag() to obtain outstanding requests associated with
the scsi host managed by the driver. Kernel’s block layer may return
stale entry for one or more outstanding requests if blk-mq is enabled.
This may lead to Kernel panic if the returned value is inaccessible or
the memory pointed by the returned value is reused.

Reference of upstream discussion -
https://patchwork.kernel.org/patch/10734933/

So to fix this issue, driver will use scsi lookup table to track
outstanding IOs at driver level and it avoids using scsi_host_find_tag().

Have done following changes in this patch,
* Allocated & initialized scsi_lookup table of type
    (struct scsiio_tracker) and of depth host's can_queue at driver load time
    and it will be deallocated at driver unload time.

* Once scmd is received, driver will take scsiio_tracker at entry
    corresponding to scmd's tag value from scsi_lookup table. Then this
    scsiio_tracker entry is initialized with proper smid, scmd, cb_idx etc.
    And this scsiio_tracker entry contents are cleared before driver
    calling scsi_done callback function.

* scmd's host_scribble variable is used to save the corresponding
    scsiio_tracker address, later at any time driver can easily retrieve the
    scmd's corresponding scsiio_tacker using this host_scribble variable.

* Whenever driver wants to get the outstanding IOs at the driver level
    then driver can go through this scsi_lookup table and if it observe
    any entry with non-null scmd then it means that scmd is outstanding
    at the driver level.

v1 change set:
Updated the patch description.

Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx>
---
   drivers/scsi/mpt3sas/mpt3sas_base.c      | 45 +++++++++++++++++++++++++++++---
   drivers/scsi/mpt3sas/mpt3sas_base.h      | 10 +++++++
   drivers/scsi/mpt3sas/mpt3sas_ctl.c       |  2 +-
   drivers/scsi/mpt3sas/mpt3sas_scsih.c     | 16 +++++-------
   drivers/scsi/mpt3sas/mpt3sas_warpdrive.c |  2 +-
   5 files changed, 60 insertions(+), 15 deletions(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
index 0a6cb8f..8e3d0d5 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -1301,7 +1301,7 @@ static int mpt3sas_remove_dead_ioc_func(void *arg)

       cmd = mpt3sas_scsih_scsi_lookup_get(ioc, smid);
       if (cmd)
-             return scsi_cmd_priv(cmd);
+             return mpt3sas_get_st_from_scmd(cmd);

       return NULL;
   }
@@ -1709,7 +1709,7 @@ static int mpt3sas_remove_dead_ioc_func(void *arg)
                              struct scsi_cmnd *scmd)
   {
       struct chain_tracker *chain_req;
-     struct scsiio_tracker *st = scsi_cmd_priv(scmd);
+     struct scsiio_tracker *st = mpt3sas_get_st_from_scmd(scmd);
       u16 smid = st->smid;
       u8 chain_offset =
          atomic_read(&ioc->chain_lookup[smid - 1].chain_offset);
@@ -3203,14 +3203,18 @@ static int mpt3sas_remove_dead_ioc_func(void *arg)
   mpt3sas_base_get_smid_scsiio(struct MPT3SAS_ADAPTER *ioc, u8 cb_idx,
       struct scsi_cmnd *scmd)
   {
-     struct scsiio_tracker *request = scsi_cmd_priv(scmd);
+     struct scsiio_tracker *request;
       unsigned int tag = scmd->request->tag;
       u16 smid;

+     scmd->host_scribble = (unsigned char *)(&ioc->scsi_lookup[tag]);
+     request = mpt3sas_get_st_from_scmd(scmd);
+
       smid = tag + 1;
       request->cb_idx = cb_idx;
       request->msix_io = _base_get_msix_index(ioc);
       request->smid = smid;
+     request->scmd = scmd;
       INIT_LIST_HEAD(&request->chain_list);
       return smid;
   }
@@ -3264,6 +3268,7 @@ void mpt3sas_base_clear_st(struct MPT3SAS_ADAPTER *ioc,
               return;
       st->cb_idx = 0xFF;
       st->direct_io = 0;
+     st->scmd = NULL;
       atomic_set(&ioc->chain_lookup[st->smid - 1].chain_offset, 0);
       st->smid = 0;
   }
@@ -4252,6 +4257,11 @@ void mpt3sas_base_clear_st(struct MPT3SAS_ADAPTER *ioc,
                   ioc->config_page, ioc->config_page_dma);
       }

+     if (ioc->scsi_lookup) {
+             free_pages((ulong)ioc->scsi_lookup, ioc->scsi_lookup_pages);
+             ioc->scsi_lookup = NULL;
+     }
+
       kfree(ioc->hpr_lookup);
       kfree(ioc->internal_lookup);
       if (ioc->chain_lookup) {
@@ -4377,6 +4387,7 @@ void mpt3sas_base_clear_st(struct MPT3SAS_ADAPTER *ioc,
               max_request_credit = min_t(u16, facts->RequestCredit,
                   MAX_HBA_QUEUE_DEPTH);

+retry:
       /* Firmware maintains additional facts->HighPriorityCredit number of
        * credits for HiPriprity Request messages, so hba queue depth will be
        * sum of max_request_credit and high priority queue depth.
@@ -4581,9 +4592,29 @@ void mpt3sas_base_clear_st(struct MPT3SAS_ADAPTER *ioc,
                            (unsigned long long)ioc->request_dma));
       total_sz += sz;

+     sz = ioc->shost->can_queue * sizeof(struct scsiio_tracker);
+     ioc->scsi_lookup_pages = get_order(sz);
+     ioc->scsi_lookup = (struct scsiio_tracker *)__get_free_pages(
+         GFP_KERNEL, ioc->scsi_lookup_pages);
+     if (!ioc->scsi_lookup) {
+             /* Retry allocating memory by reducing the queue depth */
+             if ((max_request_credit - 64) >
+                 (ioc->internal_depth + INTERNAL_SCSIIO_CMDS_COUNT)) {
+                     max_request_credit -= 64;
+                     _base_release_memory_pools(ioc);
+                     goto retry;
+             } else {
+                     ioc_err(ioc,
+                         "scsi_lookup: get_free_pages failed, sz(%d)\n",
+                         (int)sz);
+                     goto out;
+             }
+     }
+
       dinitprintk(ioc,
                   ioc_info(ioc, "scsiio(0x%p): depth(%d)\n",
                            ioc->request, ioc->scsiio_depth));
+     total_sz += sz;

       ioc->chain_depth = min_t(u32, ioc->chain_depth, MAX_CHAIN_DEPTH);
       sz = ioc->scsiio_depth * sizeof(struct chain_lookup);
@@ -6239,6 +6270,14 @@ void mpt3sas_base_clear_st(struct MPT3SAS_ADAPTER *ioc,

       spin_lock_irqsave(&ioc->scsi_lookup_lock, flags);

+     smid = 1;
+     for (i = 0; i < ioc->shost->can_queue; i++, smid++) {
+             ioc->scsi_lookup[i].cb_idx = 0xFF;
+             ioc->scsi_lookup[i].smid = smid;
+             ioc->scsi_lookup[i].scmd = NULL;
+             ioc->scsi_lookup[i].direct_io = 0;
+     }
+
       /* hi-priority queue */
       INIT_LIST_HEAD(&ioc->hpr_free_list);
       smid = ioc->hi_priority_smid;
diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.h b/drivers/scsi/mpt3sas/mpt3sas_base.h
index 19158cb..f8c82f6 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.h
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.h
@@ -816,6 +816,7 @@ struct chain_lookup {
   /**
    * struct scsiio_tracker - scsi mf request tracker
    * @smid: system message id
+ * @scmd: scsi request pointer
    * @cb_idx: callback index
    * @direct_io: To indicate whether I/O is direct (WARPDRIVE)
    * @chain_list: list of associated firmware chain tracker
@@ -823,6 +824,7 @@ struct chain_lookup {
    */
   struct scsiio_tracker {
       u16     smid;
+     struct scsi_cmnd *scmd;
       u8      cb_idx;
       u8      direct_io;
       struct pcie_sg_list pcie_sg_list;
@@ -830,6 +832,12 @@ struct scsiio_tracker {
       u16     msix_io;
   };

+static inline struct scsiio_tracker *
+mpt3sas_get_st_from_scmd(struct scsi_cmnd *scmd)
+{
+     return (struct scsiio_tracker *)scmd->host_scribble;
+}
+
   /**
    * struct request_tracker - firmware request tracker
    * @smid: system message id
@@ -1296,6 +1304,8 @@ struct MPT3SAS_ADAPTER {
       u8              *request;
       dma_addr_t      request_dma;
       u32             request_dma_sz;
+     struct scsiio_tracker *scsi_lookup;
+     ulong           scsi_lookup_pages;
       struct pcie_sg_list *pcie_sg_lookup;
       spinlock_t      scsi_lookup_lock;
       int             pending_io_count;
diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
index b2bb47c..ad43e60 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
@@ -595,7 +595,7 @@ void mpt3sas_ctl_reset_done_handler(struct MPT3SAS_ADAPTER *ioc)
                       continue;
               if (priv_data->sas_target->handle != handle)
                       continue;
-             st = scsi_cmd_priv(scmd);
+             st = mpt3sas_get_st_from_scmd(scmd);
               tm_request->TaskMID = cpu_to_le16(st->smid);
               found = 1;
       }
diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index 8bb5b8f..86d0e3c 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -1465,11 +1465,9 @@ struct scsi_cmnd *

       if (smid > 0  &&
           smid <= ioc->scsiio_depth - INTERNAL_SCSIIO_CMDS_COUNT) {
-             u32 unique_tag = smid - 1;
-
-             scmd = scsi_host_find_tag(ioc->shost, unique_tag);
+             scmd = ioc->scsi_lookup[smid - 1].scmd;
               if (scmd) {
-                     st = scsi_cmd_priv(scmd);
+                     st = mpt3sas_get_st_from_scmd(scmd);
                       if (st->cb_idx == 0xFF || st->smid == 0)
                               scmd = NULL;
               }
@@ -2819,7 +2817,7 @@ int mpt3sas_scsih_issue_locked_tm(struct MPT3SAS_ADAPTER *ioc, u16 handle,
   {
       struct MPT3SAS_ADAPTER *ioc = shost_priv(scmd->device->host);
       struct MPT3SAS_DEVICE *sas_device_priv_data;
-     struct scsiio_tracker *st = scsi_cmd_priv(scmd);
+     struct scsiio_tracker *st = mpt3sas_get_st_from_scmd(scmd);
       u16 handle;
       int r;

@@ -4466,7 +4464,7 @@ static int _scsih_set_satl_pending(struct scsi_cmnd *scmd, bool pending)
                       continue;
               count++;
               _scsih_set_satl_pending(scmd, false);
-             st = scsi_cmd_priv(scmd);
+             st = mpt3sas_get_st_from_scmd(scmd);
               mpt3sas_base_clear_st(ioc, st);
               scsi_dma_unmap(scmd);
               if (ioc->pci_error_recovery || ioc->remove_host)
@@ -5193,7 +5191,7 @@ static int _scsih_set_satl_pending(struct scsi_cmnd *scmd, bool pending)
        * WARPDRIVE: If direct_io is set then it is directIO,
        * the failed direct I/O should be redirected to volume
        */
-     st = scsi_cmd_priv(scmd);
+     st = mpt3sas_get_st_from_scmd(scmd);
       if (st->direct_io &&
            ((ioc_status & MPI2_IOCSTATUS_MASK)
             != MPI2_IOCSTATUS_SCSI_TASK_TERMINATED)) {
@@ -7335,7 +7333,7 @@ static int _scsih_set_satl_pending(struct scsi_cmnd *scmd, bool pending)
               scmd = mpt3sas_scsih_scsi_lookup_get(ioc, smid);
               if (!scmd)
                       continue;
-             st = scsi_cmd_priv(scmd);
+             st = mpt3sas_get_st_from_scmd(scmd);
               sdev = scmd->device;
               sas_device_priv_data = sdev->hostdata;
               if (!sas_device_priv_data || !sas_device_priv_data->sas_target)
@@ -10176,7 +10174,6 @@ static void pcie_device_make_active(struct MPT3SAS_ADAPTER *ioc,
       .shost_attrs                    = mpt3sas_host_attrs,
       .sdev_attrs                     = mpt3sas_dev_attrs,
       .track_queue_depth              = 1,
-     .cmd_size                       = sizeof(struct scsiio_tracker),
   };

   /* raid transport support for SAS 2.0 HBA devices */
@@ -10214,7 +10211,6 @@ static void pcie_device_make_active(struct MPT3SAS_ADAPTER *ioc,
       .shost_attrs                    = mpt3sas_host_attrs,
       .sdev_attrs                     = mpt3sas_dev_attrs,
       .track_queue_depth              = 1,
-     .cmd_size                       = sizeof(struct scsiio_tracker),
   };

   /* raid transport support for SAS 3.0 HBA devices */
diff --git a/drivers/scsi/mpt3sas/mpt3sas_warpdrive.c b/drivers/scsi/mpt3sas/mpt3sas_warpdrive.c
index cc07ba4..2a05bf3 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_warpdrive.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_warpdrive.c
@@ -259,7 +259,7 @@
       sector_t v_lba, p_lba, stripe_off, column, io_size;
       u32 stripe_sz, stripe_exp;
       u8 num_pds, cmd = scmd->cmnd[0];
-     struct scsiio_tracker *st = scsi_cmd_priv(scmd);
+     struct scsiio_tracker *st = mpt3sas_get_st_from_scmd(scmd);

       if (cmd != READ_10 && cmd != WRITE_10 &&
           cmd != READ_16 && cmd != WRITE_16)

I still think this is the wrong way of approaching it.
I'd rather using blk_mq_tagset_busy_iter() here; that would avoid the
issue mentioned.

Let's see if I can come up with a patch.

Hannes,

This API blk_mq_tagset_busy_iter() is not flexible to accommodate it
into mpt3sas driver code. For example driver can’t exit from this API
in-between if need, i.e. While processing Async Broadcast primitive
event if host reset occurs then driver has to wait for this
blk_mq_tagset_busy_iter() API to call the callback function for all
the outstanding requests and no way to quit in-between.

This is actually not true; the return value from the iter function determines if the loop should continue.
If the iter function returns false the loop will be terminated.

Cheers,

Hannes



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