aacraid: Fix RRQ overload

[ Upstream commit 3f4ce057d51a9c0ed9b01ba693df685d230ffcae ]

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>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/drivers/scsi/aacraid/aacraid.h b/drivers/scsi/aacraid/aacraid.h
index 40fe65c..18c9c06 100644 (file)
--- a/drivers/scsi/aacraid/aacraid.h
+++ b/drivers/scsi/aacraid/aacraid.h
@@ -939,6 +939,7 @@ 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*/
 };
@@ -2098,6 +2099,7 @@ static inline unsigned int cap_to_cyls(sector_t capacity, unsigned divisor)
 #define AAC_OWNER_FIRMWARE     0x106
 
 const char *aac_driverinfo(struct Scsi_Host *);
+void aac_fib_vector_assign(struct aac_dev *dev);
 struct fib *aac_fib_alloc(struct aac_dev *dev);
 int aac_fib_setup(struct aac_dev *dev);
 void aac_fib_map_free(struct aac_dev *dev);

diff --git a/drivers/scsi/aacraid/commsup.c b/drivers/scsi/aacraid/commsup.c
index 4da5749..d8e1a54 100644 (file)
--- a/drivers/scsi/aacraid/commsup.c
+++ b/drivers/scsi/aacraid/commsup.c
@@ -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
@@ -151,6 +173,12 @@ 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
         */

diff --git a/drivers/scsi/aacraid/src.c b/drivers/scsi/aacraid/src.c
index 4596e9d..81315a1 100644 (file)
--- a/drivers/scsi/aacraid/src.c
+++ b/drivers/scsi/aacraid/src.c
@@ -156,8 +156,8 @@ 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;
@@ -448,36 +448,20 @@ static int aac_src_deliver_message(struct fib *fib)
        dma_addr_t address;
        struct aac_fib_xporthdr *pFibX;
        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;