[PATCH] LOG2: Implement a general integer log2 facility in the kernel
This facility provides three entry points:
ilog2() Log base 2 of unsigned long
ilog2_u32() Log base 2 of u32
ilog2_u64() Log base 2 of u64
These facilities can either be used inside functions on dynamic data:
int do_something(long q)
{
...;
y = ilog2(x)
...;
}
Or can be used to statically initialise global variables with constant values:
unsigned n = ilog2(27);
When performing static initialisation, the compiler will report "error:
initializer element is not constant" if asked to take a log of zero or of
something not reducible to a constant. They treat negative numbers as
unsigned.
When not dealing with a constant, they fall back to using fls() which permits
them to use arch-specific log calculation instructions - such as BSR on
x86/x86_64 or SCAN on FRV - if available.
[akpm@osdl.org: MMC fix]
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Wojtek Kaniewski <wojtekka@toxygen.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c
index 21422a3..7ec7c4b 100644
--- a/drivers/infiniband/hw/mthca/mthca_provider.c
+++ b/drivers/infiniband/hw/mthca/mthca_provider.c
@@ -124,7 +124,7 @@
props->max_map_per_fmr = 255;
else
props->max_map_per_fmr =
- (1 << (32 - long_log2(mdev->limits.num_mpts))) - 1;
+ (1 << (32 - ilog2(mdev->limits.num_mpts))) - 1;
err = 0;
out:
@@ -816,7 +816,7 @@
lkey = ucmd.lkey;
}
- ret = mthca_RESIZE_CQ(dev, cq->cqn, lkey, long_log2(entries), &status);
+ ret = mthca_RESIZE_CQ(dev, cq->cqn, lkey, ilog2(entries), &status);
if (status)
ret = -EINVAL;
diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c
index 33e3ba7..d844a25 100644
--- a/drivers/infiniband/hw/mthca/mthca_qp.c
+++ b/drivers/infiniband/hw/mthca/mthca_qp.c
@@ -636,11 +636,11 @@
if (mthca_is_memfree(dev)) {
if (qp->rq.max)
- qp_context->rq_size_stride = long_log2(qp->rq.max) << 3;
+ qp_context->rq_size_stride = ilog2(qp->rq.max) << 3;
qp_context->rq_size_stride |= qp->rq.wqe_shift - 4;
if (qp->sq.max)
- qp_context->sq_size_stride = long_log2(qp->sq.max) << 3;
+ qp_context->sq_size_stride = ilog2(qp->sq.max) << 3;
qp_context->sq_size_stride |= qp->sq.wqe_shift - 4;
}
diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c
index 34d2c47..10684da 100644
--- a/drivers/infiniband/hw/mthca/mthca_srq.c
+++ b/drivers/infiniband/hw/mthca/mthca_srq.c
@@ -120,7 +120,7 @@
memset(context, 0, sizeof *context);
- logsize = long_log2(srq->max);
+ logsize = ilog2(srq->max);
context->state_logsize_srqn = cpu_to_be32(logsize << 24 | srq->srqn);
context->lkey = cpu_to_be32(srq->mr.ibmr.lkey);
context->db_index = cpu_to_be32(srq->db_index);
@@ -213,7 +213,7 @@
if (!mthca_is_memfree(dev) && (ds > dev->limits.max_desc_sz))
return -EINVAL;
- srq->wqe_shift = long_log2(ds);
+ srq->wqe_shift = ilog2(ds);
srq->srqn = mthca_alloc(&dev->srq_table.alloc);
if (srq->srqn == -1)
diff --git a/drivers/infiniband/ulp/iser/iser_memory.c b/drivers/infiniband/ulp/iser/iser_memory.c
index 5e12250..3aedd59 100644
--- a/drivers/infiniband/ulp/iser/iser_memory.c
+++ b/drivers/infiniband/ulp/iser/iser_memory.c
@@ -114,7 +114,7 @@
if (cmd_data_len > ISER_KMALLOC_THRESHOLD)
mem = (void *)__get_free_pages(GFP_NOIO,
- long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
+ ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
else
mem = kmalloc(cmd_data_len, GFP_NOIO);
@@ -211,7 +211,7 @@
if (cmd_data_len > ISER_KMALLOC_THRESHOLD)
free_pages((unsigned long)mem_copy->copy_buf,
- long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
+ ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
else
kfree(mem_copy->copy_buf);