From: Roland Dreier <roland@xxxxxxxxxxxxxxx>
Now that all fabrics are converted over to using se_cmd->t_data_sg
directly, we can drop the task sg chaining support. With the modern
memory allocation in target core, task sg chaining is needless
overhead -- we would split up the main cmd sglist into pieces, and
then splice those pieces back together instead of just using the
original list directly.
Signed-off-by: Roland Dreier <roland@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_transport.c | 89 +------------------------------
include/target/target_core_base.h | 2 -
include/target/target_core_fabric.h | 7 ---
3 files changed, 3 insertions(+), 95 deletions(-)
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index e252925..58315b0 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -3706,76 +3706,6 @@ static inline sector_t transport_limit_task_sectors(
return sectors;
}
-
-/*
- * This function can be used by HW target mode drivers to create a linked
- * scatterlist from all contiguously allocated struct se_task->task_sg[].
- * This is intended to be called during the completion path by TCM Core
- * when struct target_core_fabric_ops->check_task_sg_chaining is enabled.
- */
-void transport_do_task_sg_chain(struct se_cmd *cmd)
-{
- struct scatterlist *sg_first = NULL;
- struct scatterlist *sg_prev = NULL;
- int sg_prev_nents = 0;
- struct scatterlist *sg;
- struct se_task *task;
- u32 chained_nents = 0;
- int i;
-
- BUG_ON(!cmd->se_tfo->task_sg_chaining);
-
- /*
- * Walk the struct se_task list and setup scatterlist chains
- * for each contiguously allocated struct se_task->task_sg[].
- */
- list_for_each_entry(task, &cmd->t_task_list, t_list) {
- if (!task->task_sg)
- continue;
-
- if (!sg_first) {
- sg_first = task->task_sg;
- chained_nents = task->task_sg_nents;
- } else {
- sg_chain(sg_prev, sg_prev_nents, task->task_sg);
- chained_nents += task->task_sg_nents;
- }
- /*
- * For the padded tasks, use the extra SGL vector allocated
- * in transport_allocate_data_tasks() for the sg_prev_nents
- * offset into sg_chain() above.
- *
- * We do not need the padding for the last task (or a single
- * task), but in that case we will never use the sg_prev_nents
- * value below which would be incorrect.
- */
- sg_prev_nents = (task->task_sg_nents + 1);
- sg_prev = task->task_sg;
- }
- /*
- * Setup the starting pointer and total t_tasks_sg_linked_no including
- * padding SGs for linking and to mark the end.
- */
- cmd->t_tasks_sg_chained = sg_first;
- cmd->t_tasks_sg_chained_no = chained_nents;
-
- pr_debug("Setup cmd: %p cmd->t_tasks_sg_chained: %p and"
- " t_tasks_sg_chained_no: %u\n", cmd, cmd->t_tasks_sg_chained,
- cmd->t_tasks_sg_chained_no);
-
- for_each_sg(cmd->t_tasks_sg_chained, sg,
- cmd->t_tasks_sg_chained_no, i) {
-
- pr_debug("SG[%d]: %p page: %p length: %d offset: %d\n",
- i, sg, sg_page(sg), sg->length, sg->offset);
- if (sg_is_chain(sg))
- pr_debug("SG: %p sg_is_chain=1\n", sg);
- if (sg_is_last(sg))
- pr_debug("SG: %p sg_is_last=1\n", sg);
- }
-}
-EXPORT_SYMBOL(transport_do_task_sg_chain);
-
/*
* Break up cmd into chunks transport can handle
*/
@@ -3830,7 +3760,7 @@ transport_allocate_data_tasks(struct se_cmd *cmd,
for (i = 0; i < task_count; i++) {
struct se_task *task;
- unsigned int task_size, task_sg_nents_padded;
+ unsigned int task_size;
struct scatterlist *sg;
unsigned long flags;
int count;
@@ -3847,27 +3777,14 @@ transport_allocate_data_tasks(struct se_cmd *cmd,
* in order to calculate the number per task SGL entries
*/
task->task_sg_nents = DIV_ROUND_UP(task->task_size, PAGE_SIZE);
- /*
- * Check if the fabric module driver is requesting that all
- * struct se_task->task_sg[] be chained together.. If so,
- * then allocate an extra padding SG entry for linking and
- * marking the end of the chained SGL for every task except
- * the last one for (task_count > 1) operation, or skipping
- * the extra padding for the (task_count == 1) case.
- */
- if (cmd->se_tfo->task_sg_chaining && (i < (task_count - 1))) {
- task_sg_nents_padded = (task->task_sg_nents + 1);
- } else
- task_sg_nents_padded = task->task_sg_nents;
-
task->task_sg = kmalloc(sizeof(struct scatterlist) *
- task_sg_nents_padded, GFP_KERNEL);
+ task->task_sg_nents, GFP_KERNEL);
if (!task->task_sg) {
cmd->se_dev->transport->free_task(task);
return -ENOMEM;
}
- sg_init_table(task->task_sg, task_sg_nents_padded);
+ sg_init_table(task->task_sg, task->task_sg_nents);
task_size = task->task_size;
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 2c5c37e..0a09b85 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -571,7 +571,6 @@ struct se_cmd {
unsigned char *t_task_cdb;
unsigned char __t_task_cdb[TCM_MAX_COMMAND_SIZE];
unsigned long long t_task_lba;
- u32 t_tasks_sg_chained_no;
atomic_t t_fe_count;
atomic_t t_se_count;
atomic_t t_task_cdbs_left;
@@ -592,7 +591,6 @@ struct se_cmd {
struct completion t_transport_stop_comp;
struct completion transport_lun_fe_stop_comp;
struct completion transport_lun_stop_comp;
- struct scatterlist *t_tasks_sg_chained;
struct work_struct work;
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 13dc827..cc64a94 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -3,12 +3,6 @@
struct target_core_fabric_ops {
struct configfs_subsystem *tf_subsys;
- /*
- * Optional to signal struct se_task->task_sg[] padding entries
- * for scatterlist chaining using transport_do_task_sg_link(),
- * disabled by default
- */
- bool task_sg_chaining;
char *(*get_fabric_name)(void);
u8 (*get_fabric_proto_ident)(struct se_portal_group *);
char *(*tpg_get_wwn)(struct se_portal_group *);
@@ -124,7 +118,6 @@ int transport_generic_handle_cdb_map(struct se_cmd *);
int transport_generic_handle_data(struct se_cmd *);
int transport_generic_map_mem_to_cmd(struct se_cmd *cmd,
struct scatterlist *, u32, struct scatterlist *, u32);
-void transport_do_task_sg_chain(struct se_cmd *);
int transport_generic_new_cmd(struct se_cmd *);
void transport_generic_process_write(struct se_cmd *);
--
1.7.9.1
--
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