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aacraid: Fix RRQ overload

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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.

Fixes: 495c0217 "aacraid: MSI-x support"
Cc: stable@vger.kernel.org # v4.1

Signed-off-by: Raghava Aditya Renukunta <raghavaaditya.renukunta@pmcs.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Raghava Aditya Renukunta
2016-02-03 15:06:00 -08:00
committed by Martin K. Petersen
parent 6bf3b630d0
commit 3f4ce057d5
3 changed files with 37 additions and 23 deletions
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28
drivers/scsi/aacraid/commsup.c
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@@ -90,6 +90,28 @@ void aac_fib_map_free(struct aac_dev *dev)
dev->hw_fib_pa = 0;
}
void aac_fib_vector_assign(struct aac_dev *dev)
{
u32 i = 0;
u32 vector = 1;
struct fib *fibptr = NULL;
for (i = 0, fibptr = &dev->fibs[i];
i < (dev->scsi_host_ptr->can_queue + AAC_NUM_MGT_FIB);
i++, fibptr++) {
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;
}
}
}
/**
* aac_fib_setup - setup the fibs
* @dev: Adapter to set up
@@ -152,6 +174,12 @@ int aac_fib_setup(struct aac_dev * dev)
hw_fib_pa = hw_fib_pa +
dev->max_fib_size + sizeof(struct aac_fib_xporthdr);
}
/*
*Assign vector numbers to fibs
*/
aac_fib_vector_assign(dev);
/*
* Add the fib chain to the free list
*/