[PATCH] ib_ehca: fix compile failure on ppc64

[Kyle McMartin <kmcmartin-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

I'm getting compile failures building this driver, which I narrowed down
to the ilog2 call in ehca_get_max_hwpage_size...

ERROR: ".____ilog2_NaN" [drivers/infiniband/hw/ehca/ib_ehca.ko]
undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2

The use of shca->hca_cap_mr_pgsize is confusing the compiler, and
resulting in the __builtin_constant_p in ilog2 going insane.

I tried making it take the u32 pgsize as an argument and the expansion
of shca->_pgsize in the caller, but that failed as well. Adding a
temporary variable as below got it building again though (as did
replacing the ilog2 with fls(x) - 1.)

With this patch in place, the driver compiles on my GCC 4.6.2 here.

Signed-off-by: Kyle McMartin <kmcmarti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

--- a/drivers/infiniband/hw/ehca/ehca_mrmw.c
+++ b/drivers/infiniband/hw/ehca/ehca_mrmw.c
@@ -112,7 +112,8 @@ static u32 ehca_encode_hwpage_size(u32 pgsize)
 
 static u64 ehca_get_max_hwpage_size(struct ehca_shca *shca)
 {
-	return 1UL << ilog2(shca->hca_cap_mr_pgsize);
+	u32 pgsize = shca->hca_cap_mr_pgsize;
+	return 1UL << ilog2(pgsize);
 }
 
 static struct ehca_mr *ehca_mr_new(void)
--
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