aacraid: Fix RRQ overload

BugLink: http://bugs.launchpad.net/bugs/1572722
commit 3f4ce057d51a9c0ed9b01ba693df685d230ffcae upstream.

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"
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/drivers/scsi/aacraid/aacraid.h b/drivers/scsi/aacraid/aacraid.h
index 074878b55a0b7d9f371fe5bc57b2714e01074fdb..d044f3f273be29bde4dcb3cf2caef6c5ed35a487 100644 (file)
--- 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*/
 };
@@ -2113,6 +2114,7 @@ static inline unsigned int cap_to_cyls(sector_t capacity, unsigned divisor)
 int aac_acquire_irq(struct aac_dev *dev);
 void aac_free_irq(struct aac_dev *dev);
 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 a1f90fe849c95201f410972b34413f45e484802e..e9b4c1119eb9ea278503035ced15168e83698082 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 2aa34ea8ceb1e903781331acd3283ba264eadd53..bc0203f3d243e8e8926e1975408017d9dd5f5012 100644 (file)
--- 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;