From: Raghava Aditya Renukunta <raghavaaditya.renukunta@xxxxxxxx>
The driver utilizes an array of atomic variables to keep track of
IO submissions to each vector. To submit an IO multiple threads
iterate through the array to find a vector which has empty slots
to send an IO. The reading and updating of the variable is not atomic,
causing race conditions when a thread uses a full vector to
submit an IO.
Fixed by mapping each FIB to a vector, the submission path then uses
said vector to submit IO thereby removing the possibly of a race
condition.The vector assignment is started from 1 since vector 0 is
reserved for the use of AIF management FIBS.If the number of MSIx
vectors is 1 (MSI or INTx mode) then all the fibs are allocated to
vector 0.
Signed-off-by: Raghava Aditya Renukunta <raghavaaditya.renukunta@xxxxxxxx>
---
drivers/scsi/aacraid/aacraid.h | 1 +
drivers/scsi/aacraid/commsup.c | 12 ++++++++++++
drivers/scsi/aacraid/src.c | 30 +++++++-----------------------
3 files changed, 20 insertions(+), 23 deletions(-)
diff --git a/drivers/scsi/aacraid/aacraid.h b/drivers/scsi/aacraid/aacraid.h
index da227e8..d133c4a 100644
--- a/drivers/scsi/aacraid/aacraid.h
+++ b/drivers/scsi/aacraid/aacraid.h
@@ -944,6 +944,7 @@ struct fib {
*/
struct list_head fiblink;
void *data;
+ u32 vector_no;
struct hw_fib *hw_fib_va; /* Actual shared object */
dma_addr_t hw_fib_pa; /* physical address of hw_fib*/
};
diff --git a/drivers/scsi/aacraid/commsup.c b/drivers/scsi/aacraid/commsup.c
index b5b653c..b257d3b 100644
--- a/drivers/scsi/aacraid/commsup.c
+++ b/drivers/scsi/aacraid/commsup.c
@@ -104,6 +104,7 @@ int aac_fib_setup(struct aac_dev * dev)
struct hw_fib *hw_fib;
dma_addr_t hw_fib_pa;
int i;
+ u32 vector = 1;
while (((i = fib_map_alloc(dev)) == -ENOMEM)
&& (dev->scsi_host_ptr->can_queue > (64 - AAC_NUM_MGT_FIB))) {
@@ -150,6 +151,17 @@ int aac_fib_setup(struct aac_dev * dev)
dev->max_fib_size + sizeof(struct aac_fib_xporthdr));
hw_fib_pa = hw_fib_pa +
dev->max_fib_size + sizeof(struct aac_fib_xporthdr);
+
+ if ((dev->max_msix == 1) ||
+ (i > ((dev->scsi_host_ptr->can_queue + AAC_NUM_MGT_FIB - 1)
+ - dev->vector_cap))) {
+ fibptr->vector_no = 0;
+ } else {
+ fibptr->vector_no = vector;
+ vector++;
+ if (vector == dev->max_msix)
+ vector = 1;
+ }
}
/*
* Add the fib chain to the free list
diff --git a/drivers/scsi/aacraid/src.c b/drivers/scsi/aacraid/src.c
index 2aa34ea..bc0203f 100644
--- a/drivers/scsi/aacraid/src.c
+++ b/drivers/scsi/aacraid/src.c
@@ -156,8 +156,8 @@ static irqreturn_t aac_src_intr_message(int irq, void *dev_id)
break;
if (dev->msi_enabled && dev->max_msix > 1)
atomic_dec(&dev->rrq_outstanding[vector_no]);
- aac_intr_normal(dev, handle-1, 0, isFastResponse, NULL);
dev->host_rrq[index++] = 0;
+ aac_intr_normal(dev, handle-1, 0, isFastResponse, NULL);
if (index == (vector_no + 1) * dev->vector_cap)
index = vector_no * dev->vector_cap;
dev->host_rrq_idx[vector_no] = index;
@@ -452,36 +452,20 @@ static int aac_src_deliver_message(struct fib *fib)
#endif
u16 hdr_size = le16_to_cpu(fib->hw_fib_va->header.Size);
+ u16 vector_no;
atomic_inc(&q->numpending);
if (dev->msi_enabled && fib->hw_fib_va->header.Command != AifRequest &&
dev->max_msix > 1) {
- u_int16_t vector_no, first_choice = 0xffff;
-
- vector_no = dev->fibs_pushed_no % dev->max_msix;
- do {
- vector_no += 1;
- if (vector_no == dev->max_msix)
- vector_no = 1;
- if (atomic_read(&dev->rrq_outstanding[vector_no]) <
- dev->vector_cap)
- break;
- if (0xffff == first_choice)
- first_choice = vector_no;
- else if (vector_no == first_choice)
- break;
- } while (1);
- if (vector_no == first_choice)
- vector_no = 0;
- atomic_inc(&dev->rrq_outstanding[vector_no]);
- if (dev->fibs_pushed_no == 0xffffffff)
- dev->fibs_pushed_no = 0;
- else
- dev->fibs_pushed_no++;
+ vector_no = fib->vector_no;
fib->hw_fib_va->header.Handle += (vector_no << 16);
+ } else {
+ vector_no = 0;
}
+ atomic_inc(&dev->rrq_outstanding[vector_no]);
+
if (dev->comm_interface == AAC_COMM_MESSAGE_TYPE2) {
/* Calculate the amount to the fibsize bits */
fibsize = (hdr_size + 127) / 128 - 1;
--
1.9.1
--
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