On Fri, 2011-05-27 at 12:07 -0700, Andy Grover wrote:
> Since iscsi now allocates its own buffers and in its own thread, we don't
> need the unsolicited_data_comp completion.
>
> Signed-off-by: Andy Grover <agrover@xxxxxxxxxx>
> ---
Committed as 26bc999ea68 with a few very minor changes in order to apply
w/o patch #25-#26..
Once again, very well done for enabling direct task allocation from
iscsi RX thread context and saving the initial context switch, and the
second switch with immediate write data and/or unsolicited data out.
I am excited to see to see how much of an latency improvement this buys
gives us. Really great work Andy. :)
--nab
> drivers/target/iscsi/iscsi_target.c | 41 +++----------------------
> drivers/target/iscsi/iscsi_target_configfs.c | 13 ++------
> drivers/target/iscsi/iscsi_target_core.h | 2 -
> drivers/target/iscsi/iscsi_target_util.c | 1 -
> drivers/target/target_core_transport.c | 2 +-
> 5 files changed, 9 insertions(+), 50 deletions(-)
>
> diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
> index a36064b..e8b72d4 100644
> --- a/drivers/target/iscsi/iscsi_target.c
> +++ b/drivers/target/iscsi/iscsi_target.c
> @@ -1139,15 +1139,9 @@ attach_cmd:
> goto after_immediate_data;
> }
>
> - /*
> - * Immediate Data is present, send to the transport and block until
> - * the underlying transport plugin has allocated the buffer to
> - * receive the Immediate Write Data into.
> - */
> + /* Allocates backstore tasks */
> transport_generic_new_cmd(SE_CMD(cmd));
>
> - wait_for_completion(&cmd->unsolicited_data_comp);
> -
> if (SE_CMD(cmd)->se_cmd_flags & SCF_SE_CMD_FAILED) {
> immed_ret = IMMEDIATE_DATA_NORMAL_OPERATION;
> dump_immediate_data = 1;
> @@ -1344,7 +1338,7 @@ static int iscsit_handle_data_out(struct iscsi_conn *conn, unsigned char *buf)
> }
>
> if (cmd->unsolicited_data) {
> - int dump_unsolicited_data = 0, wait_for_transport = 0;
> + int dump_unsolicited_data = 0;
>
> if (conn->sess->sess_ops->InitialR2T) {
> printk(KERN_ERR "Received unexpected unsolicited data"
> @@ -1358,37 +1352,12 @@ static int iscsit_handle_data_out(struct iscsi_conn *conn, unsigned char *buf)
> * and Unsupported SAM WRITE Opcodes and SE resource allocation
> * failures;
> */
> +
> + /* Something's amiss if we're not in WRITE_PENDING state... */
> spin_lock_irqsave(&se_cmd->t_state_lock, flags);
> - /*
> - * Handle cases where we do or do not want to sleep on
> - * unsolicited_data_comp
> - *
> - * First, if TRANSPORT_WRITE_PENDING state has not been reached,
> - * we need assume we need to wait and sleep..
> - */
> - wait_for_transport =
> - (se_cmd->t_state != TRANSPORT_WRITE_PENDING);
> - /*
> - * For the ImmediateData=Yes cases, there will already be
> - * generic target memory allocated with the original
> - * ISCSI_OP_SCSI_CMD PDU, so do not sleep for that case.
> - *
> - * The last is a check for a delayed TASK_ABORTED status that
> - * means the data payload will be dropped because
> - * SCF_SE_CMD_FAILED has been set to indicate that an exception
> - * condition for this struct sse_cmd has occured in generic target
> - * code that requires us to drop payload.
> - */
> - wait_for_transport =
> - (se_cmd->t_state != TRANSPORT_WRITE_PENDING);
> - if ((cmd->immediate_data != 0) ||
> - (atomic_read(&se_cmd->t_transport_aborted) != 0))
> - wait_for_transport = 0;
> + WARN_ON(se_cmd->t_state != TRANSPORT_WRITE_PENDING);
> spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
>
> - if (wait_for_transport)
> - wait_for_completion(&cmd->unsolicited_data_comp);
> -
> spin_lock_irqsave(&se_cmd->t_state_lock, flags);
> if (!(se_cmd->se_cmd_flags & SCF_SUPPORTED_SAM_OPCODE) ||
> (se_cmd->se_cmd_flags & SCF_SE_CMD_FAILED))
> diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
> index 4d712cf..fafeddf 100644
> --- a/drivers/target/iscsi/iscsi_target_configfs.c
> +++ b/drivers/target/iscsi/iscsi_target_configfs.c
> @@ -1510,10 +1510,7 @@ static int iscsi_get_cmd_state(struct se_cmd *se_cmd)
>
> static void iscsi_new_cmd_failure(struct se_cmd *se_cmd)
> {
> - struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd);
> -
> - if (cmd->immediate_data || cmd->unsolicited_data)
> - complete(&cmd->unsolicited_data_comp);
> + /* We no longer sleep while core allocs (we do alloc), so we can ignore this */
> }
>
> static int iscsi_is_state_remove(struct se_cmd *se_cmd)
> @@ -1572,12 +1569,8 @@ static int lio_write_pending(struct se_cmd *se_cmd)
> {
> struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd);
>
> - if (cmd->immediate_data || cmd->unsolicited_data)
> - complete(&cmd->unsolicited_data_comp);
> - else {
> - if (iscsit_build_r2ts_for_cmd(cmd, cmd->conn, 1) < 0)
> - return PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
> - }
> + if (!cmd->immediate_data && !cmd->unsolicited_data)
> + return iscsit_build_r2ts_for_cmd(cmd, cmd->conn, 1);
>
> return 0;
> }
> diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
> index 693f8c8..fa45d87 100644
> --- a/drivers/target/iscsi/iscsi_target_core.h
> +++ b/drivers/target/iscsi/iscsi_target_core.h
> @@ -438,8 +438,6 @@ struct iscsi_cmd {
> /* R2T List */
> struct list_head cmd_r2t_list;
> struct completion reject_comp;
> - /* Semaphore used for allocating buffer */
> - struct completion unsolicited_data_comp;
> /* Timer for DataOUT */
> struct timer_list dataout_timer;
> /* Iovecs for SCSI data payload RX/TX w/ kernel level sockets */
> diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
> index 79d3b6e..c6219e5 100644
> --- a/drivers/target/iscsi/iscsi_target_util.c
> +++ b/drivers/target/iscsi/iscsi_target_util.c
> @@ -153,7 +153,6 @@ struct iscsi_cmd *iscsit_allocate_cmd(struct iscsi_conn *conn, gfp_t gfp_mask)
> INIT_LIST_HEAD(&cmd->datain_list);
> INIT_LIST_HEAD(&cmd->cmd_r2t_list);
> init_completion(&cmd->reject_comp);
> - init_completion(&cmd->unsolicited_data_comp);
> spin_lock_init(&cmd->datain_lock);
> spin_lock_init(&cmd->dataout_timeout_lock);
> spin_lock_init(&cmd->istate_lock);
> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> index 3c2c74f..7759404 100644
> --- a/drivers/target/target_core_transport.c
> +++ b/drivers/target/target_core_transport.c
> @@ -4715,7 +4715,7 @@ static int transport_new_cmd(struct se_cmd *cmd)
> }
>
> /*
> - * For WRITEs, let the iSCSI Target RX Thread know its buffer is ready..
> + * For WRITEs, let the fabric know its buffer is ready..
> * This WRITE struct se_cmd (and all of its associated struct se_task's)
> * will be added to the struct se_device execution queue after its WRITE
> * data has arrived. (ie: It gets handled by the transport processing
> --
> 1.7.1
>
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