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https://github.com/SCST-project/scst.git
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Avoid creating the second kmem_cache and allocating from it if we do not
actually need it. This should improve performance on those versions of Linux that do not need this. git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@2036 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Richard Sharpe
+65
-10
@@ -174,11 +174,16 @@ struct scst_local_tgt_specific {
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#endif
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};
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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/*
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* We use a pool of objects maintaind by the kernel so that it is less
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* likely to have to allocate them when we are in the data path.
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*
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* Note, we only need this for kernels in which we are likely to get non
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* scatterlist requests.
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*/
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static struct kmem_cache *tgt_specific_pool;
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#endif
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static LIST_HEAD(scst_local_host_list);
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static DEFINE_SPINLOCK(scst_local_host_list_lock);
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@@ -476,7 +481,9 @@ static int scst_local_queuecommand(struct scsi_cmnd *SCpnt,
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__acquires(&h->host_lock)
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__releases(&h->host_lock)
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{
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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struct scst_local_tgt_specific *tgt_specific = NULL;
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#endif
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struct scst_local_host_info *scst_lcl_host;
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struct scatterlist *sgl = NULL;
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int sgl_count = 0;
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@@ -535,8 +542,10 @@ static int scst_local_queuecommand(struct scsi_cmnd *SCpnt,
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break;
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}
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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/*
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* Get some memory to keep track of the cmnd and the done routine
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* Allocate a tgt_specific_structure. We need this in case we need
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* to construct a single element SGL.
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*/
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tgt_specific = kmem_cache_alloc(tgt_specific_pool, GFP_ATOMIC);
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if (!tgt_specific) {
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@@ -546,6 +555,13 @@ static int scst_local_queuecommand(struct scsi_cmnd *SCpnt,
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}
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tgt_specific->cmnd = SCpnt;
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tgt_specific->done = done;
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#else
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/*
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* We save a pointer to the done routine in SCpnt->scsi_done and
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* we save that as tgt specific stuff below.
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*/
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SCpnt->scsi_done = done;
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#endif
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/*
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* If the command has a request, not a scatterlist, then convert it
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@@ -612,7 +628,14 @@ static int scst_local_queuecommand(struct scsi_cmnd *SCpnt,
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break;
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}
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/*
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* Save the correct thing below depending on version
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*/
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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scst_cmd_set_tgt_priv(scst_cmd, tgt_specific);
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#else
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scst_cmd_set_tgt_priv(scst_cmd, SCpnt);
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#endif
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#ifdef CONFIG_SCST_LOCAL_FORCE_DIRECT_PROCESSING
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{
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@@ -1001,21 +1024,31 @@ static int __init scst_local_init(void)
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* Allocate a pool of structures for tgt_specific structures
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*/
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 23)
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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/*
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* We only need this for kernels where we can get non scatterlists
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*/
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tgt_specific_pool = kmem_cache_create("scst_tgt_specific",
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sizeof(struct scst_local_tgt_specific),
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0, SCST_SLAB_FLAGS, NULL);
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#endif
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#else
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tgt_specific_pool = kmem_cache_create("scst_tgt_specific",
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sizeof(struct scst_local_tgt_specific),
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0, SCST_SLAB_FLAGS, NULL, NULL);
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#endif
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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/*
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* We only need this if we could get non scatterlist requests
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*/
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if (!tgt_specific_pool) {
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printk(KERN_WARNING "%s: out of memory for "
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"tgt_specific structs",
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__func__);
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return -ENOMEM;
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}
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#endif
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ret = device_register(&scst_fake_primary);
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if (ret < 0) {
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@@ -1082,7 +1115,12 @@ bus_unreg:
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dev_unreg:
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device_unregister(&scst_fake_primary);
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destroy_kmem:
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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/*
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* We only need to do this if we could get non scatterlist requests
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*/
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kmem_cache_destroy(tgt_specific_pool);
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#endif
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goto out;
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}
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@@ -1106,11 +1144,14 @@ static void __exit scst_local_exit(void)
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*/
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scst_unregister_target_template(&scst_local_targ_tmpl);
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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/*
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* Free the pool we allocated
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* Free the pool we allocated, but we only do this if we could get
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* non scatterlist requests
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*/
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if (tgt_specific_pool)
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kmem_cache_destroy(tgt_specific_pool);
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#endif
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TRACE_EXIT();
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}
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@@ -1256,7 +1297,11 @@ static int scst_local_targ_release(struct scst_tgt *tgt)
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static int scst_local_targ_xmit_response(struct scst_cmd *scst_cmd)
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{
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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struct scst_local_tgt_specific *tgt_specific;
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#endif
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struct scsi_cmnd *SCpnt = NULL;
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void (*done)(struct scsi_cmnd *);
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TRACE_ENTRY();
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@@ -1270,7 +1315,14 @@ static int scst_local_targ_xmit_response(struct scst_cmd *scst_cmd)
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(scst_cmd_get_data_direction(scst_cmd) & SCST_DATA_READ))
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scst_copy_sg(scst_cmd, SCST_SG_COPY_TO_TARGET);
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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tgt_specific = scst_cmd_get_tgt_priv(scst_cmd);
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SCpnt = tgt_specific->cmnd;
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done = tgt_specific->done;
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#else
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SCpnt = scst_cmd_get_tgt_priv(scst_cmd);
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done = SCpnt->scsi_done;
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#endif
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/*
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* This might have to change to use the two status flags
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@@ -1281,23 +1333,20 @@ static int scst_local_targ_xmit_response(struct scst_cmd *scst_cmd)
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* Calculate the residual ...
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*/
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if (likely(!scst_get_resid(scst_cmd, &resid, &out_resid))) {
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TRACE_DBG("No residuals for request %p",
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tgt_specific->cmnd);
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TRACE_DBG("No residuals for request %p", SCpnt);
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} else {
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if (out_resid != 0)
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PRINT_ERROR("Unable to return OUT residual %d "
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"(op %02x)", out_resid,
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tgt_specific->cmnd->cmnd[0]);
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"(op %02x)", out_resid, SCpnt->cmnd[0]);
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}
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scsi_set_resid(tgt_specific->cmnd, resid);
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scsi_set_resid(SCpnt, resid);
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/*
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* It seems like there is no way to set out_resid ...
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*/
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(void)scst_local_send_resp(tgt_specific->cmnd, scst_cmd,
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tgt_specific->done,
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(void)scst_local_send_resp(SCpnt, scst_cmd, done,
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scst_cmd_get_status(scst_cmd));
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}
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@@ -1313,12 +1362,19 @@ static int scst_local_targ_xmit_response(struct scst_cmd *scst_cmd)
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static void scst_local_targ_on_free_cmd(struct scst_cmd *scst_cmd)
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{
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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struct scst_local_tgt_specific *tgt_specific;
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#endif
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TRACE_ENTRY();
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25))
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/*
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* We only have to do this if we are using these structures
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*/
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tgt_specific = scst_cmd_get_tgt_priv(scst_cmd);
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kmem_cache_free(tgt_specific_pool, tgt_specific);
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#endif
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TRACE_EXIT();
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return;
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@@ -1344,7 +1400,6 @@ static struct scst_tgt_template scst_local_targ_tmpl = {
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.name = "scst_local_tgt",
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.sg_tablesize = 0xffff,
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.xmit_response_atomic = 1,
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.enabled_attr_not_needed = 1,
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.detect = scst_local_targ_detect,
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.release = scst_local_targ_release,
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.pre_exec = scst_local_targ_pre_exec,
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