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Date: Sun, 26 Aug 2012 00:06:07 +0530
From: Naresh Kumar Inna <naresh@...lsio.com>
To: "Nicholas A. Bellinger" <nab@...ux-iscsi.org>
CC: "JBottomley@...allels.com" <JBottomley@...allels.com>,
"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
Dimitrios Michailidis <dm@...lsio.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Chethan Seshadri <chethan@...lsio.com>
Subject: Re: [PATCH 5/8] csiostor: Chelsio FCoE offload driver submission
(sources part 5).
On 8/25/2012 2:26 AM, Nicholas A. Bellinger wrote:
> On Fri, 2012-08-24 at 23:10 +0530, Naresh Kumar Inna wrote:
>> On 8/24/2012 1:18 AM, Nicholas A. Bellinger wrote:
>>> On Fri, 2012-08-24 at 03:57 +0530, Naresh Kumar Inna wrote:
>>>> This patch contains code to implement the interrupt handling and the fast
>>>> path I/O functionality. The interrupt handling includes allocation of
>>>> MSIX vectors, registering and implemeting the interrupt service routines.
>>>> The fast path I/O functionality includes posting the I/O request to firmware
>>>> via Work Requests, tracking/completing them, and handling task management
>>>> requests. SCSI midlayer host template implementation is also covered by
>>>> this patch.
>>>>
>>>> Signed-off-by: Naresh Kumar Inna <naresh@...lsio.com>
>>>> ---
>>>
>>> Hi Naresh,
>>>
>>> My review comments are inline below..
>>
>> Hi Nicholas,
>>
>> Thanks for taking the time to review the driver. Please find my replies
>> inline.
>>
>> Regards,
>> Naresh.
>>
>>>
>>>> drivers/scsi/csiostor/csio_isr.c | 631 ++++++++++
>>>> drivers/scsi/csiostor/csio_scsi.c | 2498 +++++++++++++++++++++++++++++++++++++
>>>> 2 files changed, 3129 insertions(+), 0 deletions(-)
>>>> create mode 100644 drivers/scsi/csiostor/csio_isr.c
>>>> create mode 100644 drivers/scsi/csiostor/csio_scsi.c
>>>>
>
> <SNIP>
>
>>>
>>>> diff --git a/drivers/scsi/csiostor/csio_scsi.c b/drivers/scsi/csiostor/csio_scsi.c
>>>> new file mode 100644
>>>> index 0000000..0f87b00
>>>> --- /dev/null
>>>> +++ b/drivers/scsi/csiostor/csio_scsi.c
>>>> +
>>>> +#define CSIO_SCSI_CMD_WR_SZ(_imm) \
>>>> + (sizeof(struct fw_scsi_cmd_wr) + /* WR size */ \
>>>> + ALIGN((_imm), 16)) /* Immed data */
>>>> +
>>>> +#define CSIO_SCSI_CMD_WR_SZ_16(_imm) \
>>>> + (ALIGN(CSIO_SCSI_CMD_WR_SZ((_imm)), 16))
>>>> +
>>>> +/*
>>>> + * csio_scsi_cmd - Create a SCSI CMD WR.
>>>> + * @req: IO req structure.
>>>> + *
>>>> + * Gets a WR slot in the ingress queue and initializes it with SCSI CMD WR.
>>>> + *
>>>> + */
>>>> +static inline void
>>>> +csio_scsi_cmd(struct csio_ioreq *req)
>>>> +{
>>>> + struct csio_wr_pair wrp;
>>>> + struct csio_hw *hw = req->lnode->hwp;
>>>> + struct csio_scsim *scsim = csio_hw_to_scsim(hw);
>>>> + uint32_t size = CSIO_SCSI_CMD_WR_SZ_16(scsim->proto_cmd_len);
>>>> +
>>>> + req->drv_status = csio_wr_get(hw, req->eq_idx, size, &wrp);
>>>> + if (unlikely(req->drv_status != CSIO_SUCCESS))
>>>> + return;
>>>> +
>>>> + if (wrp.size1 >= size) {
>>>> + /* Initialize WR in one shot */
>>>> + csio_scsi_init_cmd_wr(req, wrp.addr1, size);
>>>> + } else {
>>>> + uint8_t tmpwr[512];
>>>
>>> Mmmm, putting this large of a buffer on the local stack is probably not
>>> a good idea.
>>>
>>> This should become an allocation.. If it's a hot path then you'll
>>> probably want to set this up before-hand.
>>>
>>
>> The else switch above is entered only when we near the end of the DMA
>> ring. This is not a frequent occurrence. If it is a strict no-no to have
>> so many on-stack bytes, I have to think of a way re-work it to use
>> pre-allocated memory. Please let me know.
>>
>
> Considering it's used a number of times, it would be better to just
> figure out a sensible manner to pre-allocate this, especially if it's
> only a single occurrence to an individual ring held under a lock.
>
I will see what I can do - I can probably add these bytes into every
queues metadata structure.
>>>> + /*
>>>> + * Make a temporary copy of the WR and write back
>>>> + * the copy into the WR pair.
>>>> + */
>>>> + csio_scsi_init_cmd_wr(req, (void *)tmpwr, size);
>>>> + memcpy(wrp.addr1, tmpwr, wrp.size1);
>>>> + memcpy(wrp.addr2, tmpwr + wrp.size1, size - wrp.size1);
>>>> + }
>>>> +}
>>>> +
>>>> +/*
>>>> + * The following is fast path code. Therefore it is inlined with multi-line
>>>> + * macros using name substitution, thus avoiding if-else switches for
>>>> + * operation (read/write), as well as serving the purpose of code re-use.
>>>> + */
>>>> +/*
>>>> + * csio_scsi_init_ulptx_dsgl - Fill in a ULP_TX_SC_DSGL
>>>> + * @hw: HW module
>>>> + * @req: IO request
>>>> + * @sgl: ULP TX SGL pointer.
>>>> + *
>>>> + */
>>>> +#define csio_scsi_init_ultptx_dsgl(hw, req, sgl) \
>>>> +do { \
>>>> + struct ulptx_sge_pair *_sge_pair = NULL; \
>>>> + struct scatterlist *_sgel; \
>>>> + uint32_t _i = 0; \
>>>> + uint32_t _xfer_len; \
>>>> + struct list_head *_tmp; \
>>>> + struct csio_dma_buf *_dma_buf; \
>>>> + struct scsi_cmnd *scmnd = csio_scsi_cmnd((req)); \
>>>> + \
>>>> + (sgl)->cmd_nsge = htonl(ULPTX_CMD(ULP_TX_SC_DSGL) | ULPTX_MORE | \
>>>> + ULPTX_NSGE((req)->nsge)); \
>>>> + /* Now add the data SGLs */ \
>>>> + if (likely(!(req)->dcopy)) { \
>>>> + scsi_for_each_sg(scmnd, _sgel, (req)->nsge, _i) { \
>>>> + if (_i == 0) { \
>>>> + (sgl)->addr0 = cpu_to_be64( \
>>>> + sg_dma_address(_sgel)); \
>>>> + (sgl)->len0 = cpu_to_be32( \
>>>> + sg_dma_len(_sgel)); \
>>>> + _sge_pair = \
>>>> + (struct ulptx_sge_pair *)((sgl) + 1); \
>>>> + continue; \
>>>> + } \
>>>> + if ((_i - 1) & 0x1) { \
>>>> + _sge_pair->addr[1] = cpu_to_be64( \
>>>> + sg_dma_address(_sgel)); \
>>>> + _sge_pair->len[1] = cpu_to_be32( \
>>>> + sg_dma_len(_sgel)); \
>>>> + _sge_pair++; \
>>>> + } else { \
>>>> + _sge_pair->addr[0] = cpu_to_be64( \
>>>> + sg_dma_address(_sgel)); \
>>>> + _sge_pair->len[0] = cpu_to_be32( \
>>>> + sg_dma_len(_sgel)); \
>>>> + } \
>>>> + } \
>>>> + } else { \
>>>> + /* Program sg elements with driver's DDP buffer */ \
>>>> + _xfer_len = scsi_bufflen(scmnd); \
>>>> + list_for_each(_tmp, &(req)->gen_list) { \
>>>> + _dma_buf = (struct csio_dma_buf *)_tmp; \
>>>> + if (_i == 0) { \
>>>> + (sgl)->addr0 = cpu_to_be64(_dma_buf->paddr); \
>>>> + (sgl)->len0 = cpu_to_be32( \
>>>> + min(_xfer_len, _dma_buf->len)); \
>>>> + _sge_pair = \
>>>> + (struct ulptx_sge_pair *)((sgl) + 1); \
>>>> + } \
>>>> + else if ((_i - 1) & 0x1) { \
>>>> + _sge_pair->addr[1] = cpu_to_be64( \
>>>> + _dma_buf->paddr); \
>>>> + _sge_pair->len[1] = cpu_to_be32( \
>>>> + min(_xfer_len, _dma_buf->len)); \
>>>> + _sge_pair++; \
>>>> + } else { \
>>>> + _sge_pair->addr[0] = cpu_to_be64( \
>>>> + _dma_buf->paddr); \
>>>> + _sge_pair->len[0] = cpu_to_be32( \
>>>> + min(_xfer_len, _dma_buf->len)); \
>>>> + } \
>>>> + _xfer_len -= min(_xfer_len, _dma_buf->len); \
>>>> + _i++; \
>>>> + } \
>>>> + } \
>>>> +} while (0)
>>>> +
>>>
>>> I don't see any reason why this can't just be a static function..? Why
>>> is the macro usage necessary here..?
>>
>> OK, I will make this static-inline.
>>
>>>
>>>> +/*
>>>> + * csio_scsi_init_data_wr - Initialize the READ/WRITE SCSI WR.
>>>> + * @req: IO req structure.
>>>> + * @oper: read/write
>>>> + * @wrp: DMA location to place the payload.
>>>> + * @size: Size of WR (including FW WR + immed data + rsp SG entry + data SGL
>>>> + * @wrop: _READ_/_WRITE_
>>>> + *
>>>> + * Wrapper for populating fw_scsi_read_wr/fw_scsi_write_wr.
>>>> + */
>>>> +#define csio_scsi_init_data_wr(req, oper, wrp, size, wrop) \
>>>> +do { \
>>>> + struct csio_hw *_hw = (req)->lnode->hwp; \
>>>> + struct csio_rnode *_rn = (req)->rnode; \
>>>> + struct fw_scsi_##oper##_wr *__wr = (struct fw_scsi_##oper##_wr *)(wrp);\
>>>> + struct ulptx_sgl *_sgl; \
>>>> + struct csio_dma_buf *_dma_buf; \
>>>> + uint8_t _imm = csio_hw_to_scsim(_hw)->proto_cmd_len; \
>>>> + struct scsi_cmnd *scmnd = csio_scsi_cmnd((req)); \
>>>> + \
>>>> + __wr->op_immdlen = cpu_to_be32(FW_WR_OP(FW_SCSI##wrop##WR) | \
>>>> + FW_SCSI##wrop##WR_IMMDLEN(_imm)); \
>>>> + __wr->flowid_len16 = cpu_to_be32(FW_WR_FLOWID(_rn->flowid) | \
>>>> + FW_WR_LEN16( \
>>>> + CSIO_ROUNDUP((size), 16))); \
>>>> + __wr->cookie = (uintptr_t) (req); \
>>>> + __wr->iqid = (uint16_t)cpu_to_be16(csio_q_physiqid(_hw, \
>>>> + (req)->iq_idx));\
>>>> + __wr->tmo_val = (uint8_t)((req)->tmo); \
>>>> + __wr->use_xfer_cnt = 1; \
>>>> + __wr->xfer_cnt = cpu_to_be32(scsi_bufflen(scmnd)); \
>>>> + __wr->ini_xfer_cnt = cpu_to_be32(scsi_bufflen(scmnd)); \
>>>> + /* Get RSP DMA buffer */ \
>>>> + _dma_buf = &(req)->dma_buf; \
>>>> + \
>>>> + /* Prepare RSP SGL */ \
>>>> + __wr->rsp_dmalen = cpu_to_be32(_dma_buf->len); \
>>>> + __wr->rsp_dmaaddr = cpu_to_be64(_dma_buf->paddr); \
>>>> + \
>>>> + __wr->r4 = 0; \
>>>> + \
>>>> + __wr->u.fcoe.ctl_pri = 0; \
>>>> + __wr->u.fcoe.cp_en_class = 0; \
>>>> + __wr->u.fcoe.r3_lo[0] = 0; \
>>>> + __wr->u.fcoe.r3_lo[1] = 0; \
>>>> + csio_scsi_fcp_cmnd((req), (void *)((uintptr_t)(wrp) + \
>>>> + sizeof(struct fw_scsi_##oper##_wr))); \
>>>> + \
>>>> + /* Move WR pointer past command and immediate data */ \
>>>> + _sgl = (struct ulptx_sgl *) ((uintptr_t)(wrp) + \
>>>> + sizeof(struct fw_scsi_##oper##_wr) + \
>>>> + ALIGN(_imm, 16)); \
>>>> + \
>>>> + /* Fill in the DSGL */ \
>>>> + csio_scsi_init_ultptx_dsgl(_hw, (req), _sgl); \
>>>> + \
>>>> +} while (0)
>>>> +
>>>
>>> This one has four uses of CPP keys. Just turn those into macros, and
>>> leave the rest of the code in a static function.
>>>
>>
>> So what you are suggesting is to have all the lines of the macro
>> csio_scsi_init_data_wr() added into a static function, but for the ones
>> with the 4 keys. csio_scsi_init_data_wr() will then invoke this new
>> function. Is that correct?
>>
>
> Not sure how the above should actually look without actually doing it,
> but IMHO the usage of macro just obfuscates what is going on..
>
> If it's only used a few times, just inline the code into seperate static
> functions. If it's used more than a few times, then use a single static
> funciton with macro accessors for the assignment of the various '__wr'
> structure members.
>
> The larger problem with all of these macros is that you can't tell what
> is a macro and what is a function.
>
> If you need to use a CPP macro, please make sure to capitalize the name
> of the macro in order to tell the difference between the two.
>
OK, I will see what I can do to convert this macro into a function.
>>>> +/* Calculate WR size needed for fw_scsi_read_wr/fw_scsi_write_wr */
>>>> +#define csio_scsi_data_wrsz(req, oper, sz, imm) \
>>>> +do { \
>>>> + (sz) = sizeof(struct fw_scsi_##oper##_wr) + /* WR size */ \
>>>> + ALIGN((imm), 16) + /* Immed data */ \
>>>> + sizeof(struct ulptx_sgl); /* ulptx_sgl */ \
>>>> + \
>>>> + if (unlikely((req)->nsge > 1)) \
>>>> + (sz) += (sizeof(struct ulptx_sge_pair) * \
>>>> + (ALIGN(((req)->nsge - 1), 2) / 2)); \
>>>> + /* Data SGE */ \
>>>> +} while (0)
>>>> +
>>>> +/*
>>>> + * csio_scsi_data - Create a SCSI WRITE/READ WR.
>>>> + * @req: IO req structure.
>>>> + * @oper: read/write
>>>> + * @wrop: _READ_/_WRITE_ (string subsitutions to use with the FW bit field
>>>> + * macros).
>>>> + *
>>>> + * Gets a WR slot in the ingress queue and initializes it with
>>>> + * SCSI CMD READ/WRITE WR.
>>>> + *
>>>> + */
>>>> +#define csio_scsi_data(req, oper, wrop) \
>>>> +do { \
>>>> + struct csio_wr_pair _wrp; \
>>>> + uint32_t _size; \
>>>> + struct csio_hw *_hw = (req)->lnode->hwp; \
>>>> + struct csio_scsim *_scsim = csio_hw_to_scsim(_hw); \
>>>> + \
>>>> + csio_scsi_data_wrsz((req), oper, _size, _scsim->proto_cmd_len); \
>>>> + _size = ALIGN(_size, 16); \
>>>> + \
>>>> + (req)->drv_status = csio_wr_get(_hw, (req)->eq_idx, _size, &_wrp); \
>>>> + if (likely((req)->drv_status == CSIO_SUCCESS)) { \
>>>> + if (likely(_wrp.size1 >= _size)) { \
>>>> + /* Initialize WR in one shot */ \
>>>> + csio_scsi_init_data_wr((req), oper, _wrp.addr1, \
>>>> + _size, wrop); \
>>>> + } else { \
>>>> + uint8_t tmpwr[512]; \
>>>> + /* \
>>>> + * Make a temporary copy of the WR and write back \
>>>> + * the copy into the WR pair. \
>>>> + */ \
>>>> + csio_scsi_init_data_wr((req), oper, (void *)tmpwr, \
>>>> + _size, wrop); \
>>>> + memcpy(_wrp.addr1, tmpwr, _wrp.size1); \
>>>> + memcpy(_wrp.addr2, tmpwr + _wrp.size1, \
>>>> + _size - _wrp.size1); \
>>>> + } \
>>>> + } \
>>>> +} while (0)
>>>> +
>>>
>>> Ditto on this one, along with the tmpwr[512] stack usage..
>>>
>>>> +static inline void
>>>> +csio_scsi_abrt_cls(struct csio_ioreq *req, bool abort)
>>>> +{
>>>> + struct csio_wr_pair wrp;
>>>> + struct csio_hw *hw = req->lnode->hwp;
>>>> + uint32_t size = ALIGN(sizeof(struct fw_scsi_abrt_cls_wr), 16);
>>>> +
>>>> + req->drv_status = csio_wr_get(hw, req->eq_idx, size, &wrp);
>>>> + if (req->drv_status != CSIO_SUCCESS)
>>>> + return;
>>>> +
>>>> + if (wrp.size1 >= size) {
>>>> + /* Initialize WR in one shot */
>>>> + csio_scsi_init_abrt_cls_wr(req, wrp.addr1, size, abort);
>>>> + } else {
>>>> + uint8_t tmpwr[512];
>>>
>>> Ditto here on local scope stack usage..
>>>
>>>> + /*
>>>> + * Make a temporary copy of the WR and write back
>>>> + * the copy into the WR pair.
>>>> + */
>>>> + csio_scsi_init_abrt_cls_wr(req, (void *)tmpwr, size, abort);
>>>> + memcpy(wrp.addr1, tmpwr, wrp.size1);
>>>> + memcpy(wrp.addr2, tmpwr + wrp.size1, size - wrp.size1);
>>>> + }
>>>> +}
>>>> +
>>>> +/*****************************************************************************/
>>>> +/* START: SCSI SM */
>>>> +/*****************************************************************************/
>>>> +static void
>>>> +csio_scsis_uninit(struct csio_ioreq *req, enum csio_scsi_ev evt)
>>>> +{
>>>> + struct csio_hw *hw = req->lnode->hwp;
>>>> + struct csio_scsim *scsim = csio_hw_to_scsim(hw);
>>>> +
>>>> + switch (evt) {
>>>> +
>>>> + case CSIO_SCSIE_START_IO:
>>>
>>> Extra space between start of first switch case
>>
>> OK, I will remove it. Is there any tool that catches such deviations?
>> checkpath.pl didnt report it.
>>
>
> Sorry, can't help you there.. ;)
>
>>>
>>>> +
>>>> +/**
>>>> + * csio_queuecommand_lck - Entry point to kickstart an I/O request.
>>>> + * @cmnd: The I/O request from ML.
>>>> + * @done: The ML callback routine.
>>>> + *
>>>> + * This routine does the following:
>>>> + * - Checks for HW and Rnode module readiness.
>>>> + * - Gets a free ioreq structure (which is already initialized
>>>> + * to uninit during its allocation).
>>>> + * - Maps SG elements.
>>>> + * - Initializes ioreq members.
>>>> + * - Kicks off the SCSI state machine for this IO.
>>>> + * - Returns busy status on error.
>>>> + */
>>>> +static int
>>>> +csio_queuecommand_lck(struct scsi_cmnd *cmnd, void (*done)(struct scsi_cmnd *))
>>>> +{
>>>> + struct csio_lnode *ln = shost_priv(cmnd->device->host);
>>>> + struct csio_hw *hw = csio_lnode_to_hw(ln);
>>>> + struct csio_scsim *scsim = csio_hw_to_scsim(hw);
>>>> + struct csio_rnode *rn = (struct csio_rnode *)(cmnd->device->hostdata);
>>>> + struct csio_ioreq *ioreq = NULL;
>>>> + unsigned long flags;
>>>> + int nsge = 0;
>>>> + int rv = SCSI_MLQUEUE_HOST_BUSY, nr;
>>>> + csio_retval_t retval;
>>>> + int cpu;
>>>> + struct csio_scsi_qset *sqset;
>>>> + struct fc_rport *rport = starget_to_rport(scsi_target(cmnd->device));
>>>> +
>>>> + if (!blk_rq_cpu_valid(cmnd->request))
>>>> + cpu = smp_processor_id();
>>>> + else
>>>> + cpu = cmnd->request->cpu;
>>>> +
>>>> + sqset = &hw->sqset[ln->portid][cpu];
>>>> +
>>>> + nr = fc_remote_port_chkready(rport);
>>>> + if (nr) {
>>>> + cmnd->result = nr;
>>>> + csio_inc_stats(scsim, n_rn_nr_error);
>>>> + goto err_done;
>>>> + }
>>>> +
>>>> + if (unlikely(!csio_is_hw_ready(hw))) {
>>>> + cmnd->result = (DID_REQUEUE << 16);
>>>> + csio_inc_stats(scsim, n_hw_nr_error);
>>>> + goto err_done;
>>>> + }
>>>> +
>>>> + /* Get req->nsge, if there are SG elements to be mapped */
>>>> + nsge = scsi_dma_map(cmnd);
>>>> + if (unlikely(nsge < 0)) {
>>>> + csio_inc_stats(scsim, n_dmamap_error);
>>>> + goto err;
>>>> + }
>>>> +
>>>> + /* Do we support so many mappings? */
>>>> + if (unlikely(nsge > scsim->max_sge)) {
>>>> + csio_warn(hw,
>>>> + "More SGEs than can be supported."
>>>> + " SGEs: %d, Max SGEs: %d\n", nsge, scsim->max_sge);
>>>> + csio_inc_stats(scsim, n_unsupp_sge_error);
>>>> + goto err_dma_unmap;
>>>> + }
>>>> +
>>>> + /* Get a free ioreq structure - SM is already set to uninit */
>>>> + ioreq = csio_get_scsi_ioreq_lock(hw, scsim);
>>>> + if (!ioreq) {
>>>> + csio_err(hw, "Out of I/O request elements. Active #:%d\n",
>>>> + scsim->stats.n_active);
>>>> + csio_inc_stats(scsim, n_no_req_error);
>>>> + goto err_dma_unmap;
>>>> + }
>>>> +
>>>> + ioreq->nsge = nsge;
>>>> + ioreq->lnode = ln;
>>>> + ioreq->rnode = rn;
>>>> + ioreq->iq_idx = sqset->iq_idx;
>>>> + ioreq->eq_idx = sqset->eq_idx;
>>>> + ioreq->wr_status = 0;
>>>> + ioreq->drv_status = CSIO_SUCCESS;
>>>> + csio_scsi_cmnd(ioreq) = (void *)cmnd;
>>>> + ioreq->tmo = 0;
>>>> +
>>>> + switch (cmnd->sc_data_direction) {
>>>> + case DMA_BIDIRECTIONAL:
>>>> + ioreq->datadir = CSIO_IOREQF_DMA_BIDI;
>>>> + csio_inc_stats(ln, n_control_requests);
>>>> + break;
>>>> + case DMA_TO_DEVICE:
>>>> + ioreq->datadir = CSIO_IOREQF_DMA_WRITE;
>>>> + csio_inc_stats(ln, n_output_requests);
>>>> + ln->stats.n_output_bytes += scsi_bufflen(cmnd);
>>>> + break;
>>>> + case DMA_FROM_DEVICE:
>>>> + ioreq->datadir = CSIO_IOREQF_DMA_READ;
>>>> + csio_inc_stats(ln, n_input_requests);
>>>> + ln->stats.n_input_bytes += scsi_bufflen(cmnd);
>>>> + break;
>>>> + case DMA_NONE:
>>>> + ioreq->datadir = CSIO_IOREQF_DMA_NONE;
>>>> + csio_inc_stats(ln, n_control_requests);
>>>> + break;
>>>> + default:
>>>> + CSIO_DB_ASSERT(0);
>>>> + break;
>>>> + }
>>>> +
>>>> + /* Set cbfn */
>>>> + ioreq->io_cbfn = csio_scsi_cbfn;
>>>> +
>>>> + /* Needed during abort */
>>>> + cmnd->host_scribble = (unsigned char *)ioreq;
>>>> + cmnd->scsi_done = done;
>>>> + cmnd->SCp.Message = 0;
>>>> +
>>>> + /* Kick off SCSI IO SM on the ioreq */
>>>> + spin_lock_irqsave(&hw->lock, flags);
>>>> + retval = csio_scsi_start_io(ioreq);
>>>> + spin_unlock_irqrestore(&hw->lock, flags);
>>>> +
>>>> + if (retval != CSIO_SUCCESS) {
>>>> + csio_err(hw, "ioreq: %p couldnt be started, status:%d\n",
>>>> + ioreq, retval);
>>>> + csio_inc_stats(scsim, n_busy_error);
>>>> + goto err_put_req;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +
>>>> +err_put_req:
>>>> + csio_put_scsi_ioreq_lock(hw, scsim, ioreq);
>>>> +err_dma_unmap:
>>>> + if (nsge > 0)
>>>> + scsi_dma_unmap(cmnd);
>>>> +err:
>>>> + return rv;
>>>> +
>>>> +err_done:
>>>> + done(cmnd);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static DEF_SCSI_QCMD(csio_queuecommand);
>>>> +
>>>
>>> This means that your running with the host_lock held.. I'm not sure if
>>> that is really what you want to do as it really end's up killing
>>> multi-lun small packet performance..
>>>
>>> How about dropping DEF_SCSI_QCMD usage here, and figure out what
>>> actually needs to be protected by the SCSI host_lock within
>>> csio_queuecommand_lck()..?
>>
>> It is on my TODO list for the next version of the driver, after the
>> initial submission. Per the current design, we shouldnt need the
>> host_lock to be held, but I would like to test this change thoroughly
>> before I submit it.
>>
>
> Sure, it's really quite easy to convert and these days the majority of
> high performance LLDs do run in host-lock-less mode.
>
> IIRC the libfc based FCoE initiator driver is doing this too..
>
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