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Date: Fri, 12 Sep 2014 16:05:38 +0200
From: Tomas Henzl <thenzl@...hat.com>
To: Ching Huang <ching2048@...ca.com.tw>, hch@...radead.org,
jbottomley@...allels.com, dan.carpenter@...cle.com,
agordeev@...hat.com, linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] arcmsr: simplify of updating doneq_index and postq_index
On 09/12/2014 10:22 AM, Ching Huang wrote:
> From: Ching Huang <ching2048@...ca.com.tw>
>
> 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 ?
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 ?
Thanks,
Tomas
>
> Signed-off-by: Ching Huang <ching2048@...ca.com.tw>
> ---
>
> 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(®->host_int_status) & ARCMSR_HBCMU_OUTBOUND_POSTQUEUE_ISR) && (i++ < ARCMSR_MAX_OUTSTANDING_CMD)) {
> /*need to do*/
> flag_ccb = readl(®->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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