[SCSI] libfc: fcoe_transport_create fails in single-CPU environment

Starting fcoe fails at fcoe_transport_create when attempting to allocate a
pool of 4K exchanges on a 64-bit single-CPU environment because the call to
__alloc_percpu() is greater than the max of 32K.  This patch reduces the
number of exchanges to fit within the maximum allowed space.

[ Whitespace problems fixed by Robert Love to satisfy chechpatch.pl ]

Signed-off-by: Steven Clark <sclark@crossbeam.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index 630291f01826..aceffadb21c7 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -2263,7 +2263,18 @@ struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lport,
         mp->class = class;
         /* adjust em exch xid range for offload */
         mp->min_xid = min_xid;
-        mp->max_xid = max_xid;
+
+       /* reduce range so per cpu pool fits into PCPU_MIN_UNIT_SIZE pool */
+        pool_exch_range = (PCPU_MIN_UNIT_SIZE - sizeof(*pool)) /
+                sizeof(struct fc_exch *);
+        if ((max_xid - min_xid + 1) / (fc_cpu_mask + 1) > pool_exch_range) {
+                mp->max_xid = pool_exch_range * (fc_cpu_mask + 1) +
+                        min_xid - 1;
+        } else {
+                mp->max_xid = max_xid;
+                pool_exch_range = (mp->max_xid - mp->min_xid + 1) /
+                        (fc_cpu_mask + 1);
+        }
 
         mp->ep_pool = mempool_create_slab_pool(2, fc_em_cachep);
         if (!mp->ep_pool)
@@ -2274,7 +2285,6 @@ struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lport,
          * divided across all cpus. The exch pointers array memory is
          * allocated for exch range per pool.
          */
-        pool_exch_range = (mp->max_xid - mp->min_xid + 1) / (fc_cpu_mask + 1);
         mp->pool_max_index = pool_exch_range - 1;
 
         /*