Re: [PATCH v4 2/2] arcmsr: simplify of updating doneq_index and postq_index

From: Tomas Henzl
Date: Mon Sep 15 2014 - 06:26:57 EST

On 09/15/2014 06:34 AM, Ching Huang wrote:
> On Fri, 2014-09-12 at 16:05 +0200, Tomas Henzl wrote:
>> On 09/12/2014 10:22 AM, Ching Huang wrote:
>>> From: Ching Huang <ching2048@xxxxxxxxxxxx>
>>>
>>> This patch is to modify previous patch 16/17 and it is relative to
>>> http://git.infradead.org/users/hch/scsi-queue.git/tree/arcmsr-for-3.18:/drivers/scsi/arcmsr
>>>
>>> change in v4:
>>> 1. clean up of duplicate variable declaration in switch.
>>> 2. simplify of updating doneq_index and postq_index
>>> 3. fix spin_lock area in arcmsr_hbaD_polling_ccbdone
>> The intention of the doneq_lock is to protect the pmu->doneq_index and the associated buffer,
>> right? Why is the spinlock not used on other places accessing the doneq_index
>> like arcmsr_done4abort_postqueue or arcmsr_hbaD_postqueue_isr ?
> In fact, in original code arcmsr_hbaD_postqueue_isr has spinlock with a larger area.
> As to arcmsr_done4abort_postqueue, it should be protected as below.
>
> @@ -1182,35 +1178,25 @@ static void arcmsr_done4abort_postqueue(
> break;
> case ACB_ADAPTER_TYPE_D: {
> struct MessageUnit_D *pmu = acb->pmuD;
> - uint32_t ccb_cdb_phy, outbound_write_pointer;
> - uint32_t doneq_index, index_stripped, addressLow, residual;
> - bool error;
> - struct CommandControlBlock *pCCB;
> + uint32_t outbound_write_pointer;
> + uint32_t doneq_index, index_stripped, addressLow, residual, toggle;
> + unsigned long flags;
>
> - outbound_write_pointer = pmu->done_qbuffer[0].addressLow + 1;
> - doneq_index = pmu->doneq_index;
> residual = atomic_read(&acb->ccboutstandingcount);
> for (i = 0; i < residual; i++) {
> - while ((doneq_index & 0xFFF) !=
> + spin_lock_irqsave(&acb->doneq_lock, flags);
> + outbound_write_pointer =
> + pmu->done_qbuffer[0].addressLow + 1;
> + doneq_index = pmu->doneq_index;
> + if ((doneq_index & 0xFFF) !=
> (outbound_write_pointer & 0xFFF)) {
> - if (doneq_index & 0x4000) {
> - index_stripped = doneq_index & 0xFFF;
> - index_stripped += 1;
> - index_stripped %=
> - ARCMSR_MAX_ARC1214_DONEQUEUE;
> - pmu->doneq_index = index_stripped ?
> - (index_stripped | 0x4000) :
> - (index_stripped + 1);
> - } else {
> - index_stripped = doneq_index;
> - index_stripped += 1;
> - index_stripped %=
> - ARCMSR_MAX_ARC1214_DONEQUEUE;
> - pmu->doneq_index = index_stripped ?
> - index_stripped :
> - ((index_stripped | 0x4000) + 1);
> - }
> + toggle = doneq_index & 0x4000;
> + index_stripped = (doneq_index & 0xFFF) + 1;
> + index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
> + pmu->doneq_index = index_stripped ? (index_stripped | toggle) :
> + ((toggle ^ 0x4000) + 1);
> doneq_index = pmu->doneq_index;
> + spin_unlock_irqrestore(&acb->doneq_lock, flags);
> addressLow = pmu->done_qbuffer[doneq_index &
> 0xFFF].addressLow;
> ccb_cdb_phy = (addressLow & 0xFFFFFFF0);
> @@ -1224,11 +1210,10 @@ static void arcmsr_done4abort_postqueue(
> arcmsr_drain_donequeue(acb, pCCB, error);
> writel(doneq_index,
> pmu->outboundlist_read_pointer);
> + } else {
> + spin_unlock_irqrestore(&acb->doneq_lock, flags);
> + mdelay(10);
> }
> - mdelay(10);
> - outbound_write_pointer =
> - pmu->done_qbuffer[0].addressLow + 1;
> - doneq_index = pmu->doneq_index;
> }
> pmu->postq_index = 0;
> pmu->doneq_index = 0x40FF;
>
>
>> And in arcmsr_hbaD_polling_ccbdone the code looks so:
>>
>> spin_unlock_irqrestore(&acb->doneq_lock, flags);
>> doneq_index = pmu->doneq_index;
>> flag_ccb = pmu->done_qbuffer[doneq_index & 0xFFF].addressLow;
>> you unlock^ and after that is the value read and used
>> Seems to me that I probably don't understand what the spinlock should protect.
>> Could you explain ?
> You are right. above code should change to

ok, awaiting a v5.

>
> doneq_index = pmu->doneq_index;
> spin_unlock_irqrestore(&acb->doneq_lock, flags);
> flag_ccb = pmu->done_qbuffer[doneq_index & 0xFFF].addressLow;
>> Thanks,
>> Tomas
>>
>>
>>
>>> Signed-off-by: Ching Huang <ching2048@xxxxxxxxxxxx>
>>> ---
>>>
>>> diff -uprN a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c
>>> --- a/drivers/scsi/arcmsr/arcmsr_hba.c 2014-09-12 12:43:16.956653000 +0800
>>> +++ b/drivers/scsi/arcmsr/arcmsr_hba.c 2014-09-12 15:00:23.516069000 +0800
>>> @@ -1121,7 +1121,7 @@ static void arcmsr_drain_donequeue(struc
>>> static void arcmsr_done4abort_postqueue(struct AdapterControlBlock *acb)
>>> {
>>> int i = 0;
>>> - uint32_t flag_ccb;
>>> + uint32_t flag_ccb, ccb_cdb_phy;
>>> struct ARCMSR_CDB *pARCMSR_CDB;
>>> bool error;
>>> struct CommandControlBlock *pCCB;
>>> @@ -1165,10 +1165,6 @@ static void arcmsr_done4abort_postqueue(
>>> break;
>>> case ACB_ADAPTER_TYPE_C: {
>>> struct MessageUnit_C __iomem *reg = acb->pmuC;
>>> - struct ARCMSR_CDB *pARCMSR_CDB;
>>> - uint32_t flag_ccb, ccb_cdb_phy;
>>> - bool error;
>>> - struct CommandControlBlock *pCCB;
>>> while ((readl(&reg->host_int_status) & ARCMSR_HBCMU_OUTBOUND_POSTQUEUE_ISR) && (i++ < ARCMSR_MAX_OUTSTANDING_CMD)) {
>>> /*need to do*/
>>> flag_ccb = readl(&reg->outbound_queueport_low);
>>> @@ -1182,10 +1178,8 @@ static void arcmsr_done4abort_postqueue(
>>> break;
>>> case ACB_ADAPTER_TYPE_D: {
>>> struct MessageUnit_D *pmu = acb->pmuD;
>>> - uint32_t ccb_cdb_phy, outbound_write_pointer;
>>> - uint32_t doneq_index, index_stripped, addressLow, residual;
>>> - bool error;
>>> - struct CommandControlBlock *pCCB;
>>> + uint32_t outbound_write_pointer;
>>> + uint32_t doneq_index, index_stripped, addressLow, residual, toggle;
>>>
>>> outbound_write_pointer = pmu->done_qbuffer[0].addressLow + 1;
>>> doneq_index = pmu->doneq_index;
>>> @@ -1193,23 +1187,11 @@ static void arcmsr_done4abort_postqueue(
>>> for (i = 0; i < residual; i++) {
>>> while ((doneq_index & 0xFFF) !=
>>> (outbound_write_pointer & 0xFFF)) {
>>> - if (doneq_index & 0x4000) {
>>> - index_stripped = doneq_index & 0xFFF;
>>> - index_stripped += 1;
>>> - index_stripped %=
>>> - ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> - pmu->doneq_index = index_stripped ?
>>> - (index_stripped | 0x4000) :
>>> - (index_stripped + 1);
>>> - } else {
>>> - index_stripped = doneq_index;
>>> - index_stripped += 1;
>>> - index_stripped %=
>>> - ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> - pmu->doneq_index = index_stripped ?
>>> - index_stripped :
>>> - ((index_stripped | 0x4000) + 1);
>>> - }
>>> + toggle = doneq_index & 0x4000;
>>> + index_stripped = (doneq_index & 0xFFF) + 1;
>>> + index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> + pmu->doneq_index = index_stripped ? (index_stripped | toggle) :
>>> + ((toggle ^ 0x4000) + 1);
>>> doneq_index = pmu->doneq_index;
>>> addressLow = pmu->done_qbuffer[doneq_index &
>>> 0xFFF].addressLow;
>>> @@ -1461,7 +1443,7 @@ static void arcmsr_post_ccb(struct Adapt
>>> case ACB_ADAPTER_TYPE_D: {
>>> struct MessageUnit_D *pmu = acb->pmuD;
>>> u16 index_stripped;
>>> - u16 postq_index;
>>> + u16 postq_index, toggle;
>>> unsigned long flags;
>>> struct InBound_SRB *pinbound_srb;
>>>
>>> @@ -1472,19 +1454,11 @@ static void arcmsr_post_ccb(struct Adapt
>>> pinbound_srb->addressLow = dma_addr_lo32(cdb_phyaddr);
>>> pinbound_srb->length = ccb->arc_cdb_size >> 2;
>>> arcmsr_cdb->msgContext = dma_addr_lo32(cdb_phyaddr);
>>> - if (postq_index & 0x4000) {
>>> - index_stripped = postq_index & 0xFF;
>>> - index_stripped += 1;
>>> - index_stripped %= ARCMSR_MAX_ARC1214_POSTQUEUE;
>>> - pmu->postq_index = index_stripped ?
>>> - (index_stripped | 0x4000) : index_stripped;
>>> - } else {
>>> - index_stripped = postq_index;
>>> - index_stripped += 1;
>>> - index_stripped %= ARCMSR_MAX_ARC1214_POSTQUEUE;
>>> - pmu->postq_index = index_stripped ? index_stripped :
>>> - (index_stripped | 0x4000);
>>> - }
>>> + toggle = postq_index & 0x4000;
>>> + index_stripped = postq_index + 1;
>>> + index_stripped &= (ARCMSR_MAX_ARC1214_POSTQUEUE - 1);
>>> + pmu->postq_index = index_stripped ? (index_stripped | toggle) :
>>> + (toggle ^ 0x4000);
>>> writel(postq_index, pmu->inboundlist_write_pointer);
>>> spin_unlock_irqrestore(&acb->postq_lock, flags);
>>> break;
>>> @@ -1999,7 +1973,7 @@ static void arcmsr_hbaC_postqueue_isr(st
>>>
>>> static void arcmsr_hbaD_postqueue_isr(struct AdapterControlBlock *acb)
>>> {
>>> - u32 outbound_write_pointer, doneq_index, index_stripped;
>>> + u32 outbound_write_pointer, doneq_index, index_stripped, toggle;
>>> uint32_t addressLow, ccb_cdb_phy;
>>> int error;
>>> struct MessageUnit_D *pmu;
>>> @@ -2013,21 +1987,11 @@ static void arcmsr_hbaD_postqueue_isr(st
>>> doneq_index = pmu->doneq_index;
>>> if ((doneq_index & 0xFFF) != (outbound_write_pointer & 0xFFF)) {
>>> do {
>>> - if (doneq_index & 0x4000) {
>>> - index_stripped = doneq_index & 0xFFF;
>>> - index_stripped += 1;
>>> - index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> - pmu->doneq_index = index_stripped
>>> - ? (index_stripped | 0x4000) :
>>> - (index_stripped + 1);
>>> - } else {
>>> - index_stripped = doneq_index;
>>> - index_stripped += 1;
>>> - index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> - pmu->doneq_index = index_stripped
>>> - ? index_stripped :
>>> - ((index_stripped | 0x4000) + 1);
>>> - }
>>> + toggle = doneq_index & 0x4000;
>>> + index_stripped = (doneq_index & 0xFFF) + 1;
>>> + index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> + pmu->doneq_index = index_stripped ? (index_stripped | toggle) :
>>> + ((toggle ^ 0x4000) + 1);
>>> doneq_index = pmu->doneq_index;
>>> addressLow = pmu->done_qbuffer[doneq_index &
>>> 0xFFF].addressLow;
>>> @@ -2843,7 +2807,7 @@ static bool arcmsr_hbaD_get_config(struc
>>> char __iomem *iop_firm_version;
>>> char __iomem *iop_device_map;
>>> u32 count;
>>> - struct MessageUnit_D *reg ;
>>> + struct MessageUnit_D *reg;
>>> void *dma_coherent2;
>>> dma_addr_t dma_coherent_handle2;
>>> struct pci_dev *pdev = acb->pdev;
>>> @@ -3176,7 +3140,7 @@ static int arcmsr_hbaD_polling_ccbdone(s
>>> {
>>> bool error;
>>> uint32_t poll_ccb_done = 0, poll_count = 0, flag_ccb, ccb_cdb_phy;
>>> - int rtn, doneq_index, index_stripped, outbound_write_pointer;
>>> + int rtn, doneq_index, index_stripped, outbound_write_pointer, toggle;
>>> unsigned long flags;
>>> struct ARCMSR_CDB *arcmsr_cdb;
>>> struct CommandControlBlock *pCCB;
>>> @@ -3185,9 +3149,11 @@ static int arcmsr_hbaD_polling_ccbdone(s
>>> polling_hbaD_ccb_retry:
>>> poll_count++;
>>> while (1) {
>>> + spin_lock_irqsave(&acb->doneq_lock, flags);
>>> outbound_write_pointer = pmu->done_qbuffer[0].addressLow + 1;
>>> doneq_index = pmu->doneq_index;
>>> if ((outbound_write_pointer & 0xFFF) == (doneq_index & 0xFFF)) {
>>> + spin_unlock_irqrestore(&acb->doneq_lock, flags);
>>> if (poll_ccb_done) {
>>> rtn = SUCCESS;
>>> break;
>>> @@ -3200,21 +3166,11 @@ polling_hbaD_ccb_retry:
>>> goto polling_hbaD_ccb_retry;
>>> }
>>> }
>>> - spin_lock_irqsave(&acb->doneq_lock, flags);
>>> - if (doneq_index & 0x4000) {
>>> - index_stripped = doneq_index & 0xFFF;
>>> - index_stripped += 1;
>>> - index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> - pmu->doneq_index = index_stripped ?
>>> - (index_stripped | 0x4000) :
>>> - (index_stripped + 1);
>>> - } else {
>>> - index_stripped = doneq_index;
>>> - index_stripped += 1;
>>> - index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> - pmu->doneq_index = index_stripped ? index_stripped :
>>> - ((index_stripped | 0x4000) + 1);
>>> - }
>>> + toggle = doneq_index & 0x4000;
>>> + index_stripped = (doneq_index & 0xFFF) + 1;
>>> + index_stripped %= ARCMSR_MAX_ARC1214_DONEQUEUE;
>>> + pmu->doneq_index = index_stripped ? (index_stripped | toggle) :
>>> + ((toggle ^ 0x4000) + 1);
>>> spin_unlock_irqrestore(&acb->doneq_lock, flags);
>>> doneq_index = pmu->doneq_index;
>>> flag_ccb = pmu->done_qbuffer[doneq_index & 0xFFF].addressLow;
>>>
>>>
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