From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932707AbdL1RiD (ORCPT ); Thu, 28 Dec 2017 12:38:03 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60274 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932646AbdL1RfA (ORCPT ); Thu, 28 Dec 2017 12:35:00 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Eli Cohen" , "Leon Romanovsky" , "Ilya Lesokhin" , "Doug Ledford" Date: Thu, 28 Dec 2017 17:05:44 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 053/204] IB/mlx5: Simplify mlx5_ib_cont_pages In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.52-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ilya Lesokhin commit d67bc5d4e3e100d762c0f57ea67f28bc219698a6 upstream. The patch simplifies mlx5_ib_cont_pages and fixes the following issues in the original implementation: First issues is related to alignment of the PFNs. After the check base + p != PFN, the alignment of the PFN wasn't checked. So the PFN sequence 0, 1, 1, 2 would result in a page_shift of 13 even though the 3rd PFN is not 8KB aligned. This wasn't actually a bug because it was supported by all the existing mlx5 compatible device, but we don't want to require this support in all future devices. Another issue is because the inner loop didn't advance PFN so the test "if (base + p != pfn)" always failed for SGE with len > (1< Reviewed-by: Eli Cohen Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/infiniband/hw/mlx5/mem.c | 47 +++++++++++++++------------------------- 1 file changed, 17 insertions(+), 30 deletions(-) --- a/drivers/infiniband/hw/mlx5/mem.c +++ b/drivers/infiniband/hw/mlx5/mem.c @@ -46,46 +46,33 @@ void mlx5_ib_cont_pages(struct ib_umem * { unsigned long tmp; unsigned long m; - int i, k; - u64 base = 0; - int p = 0; - int skip; - int mask; - u64 len; - u64 pfn; + u64 base = ~0, p = 0; + u64 len, pfn; + int i = 0; struct scatterlist *sg; int entry; addr = addr >> PAGE_SHIFT; tmp = (unsigned long)addr; m = find_first_bit(&tmp, BITS_PER_LONG); - skip = 1 << m; - mask = skip - 1; - i = 0; + for_each_sg(umem->sg_head.sgl, sg, umem->nmap, entry) { len = sg_dma_len(sg) >> PAGE_SHIFT; pfn = sg_dma_address(sg) >> PAGE_SHIFT; - for (k = 0; k < len; k++) { - if (!(i & mask)) { - tmp = (unsigned long)pfn; - m = min_t(unsigned long, m, find_first_bit(&tmp, BITS_PER_LONG)); - skip = 1 << m; - mask = skip - 1; - base = pfn; - p = 0; - } else { - if (base + p != pfn) { - tmp = (unsigned long)p; - m = find_first_bit(&tmp, BITS_PER_LONG); - skip = 1 << m; - mask = skip - 1; - base = pfn; - p = 0; - } - } - p++; - i++; + if (base + p != pfn) { + /* If either the offset or the new + * base are unaligned update m + */ + tmp = (unsigned long)(pfn | p); + if (!IS_ALIGNED(tmp, 1 << m)) + m = find_first_bit(&tmp, BITS_PER_LONG); + + base = pfn; + p = 0; } + + p += len; + i += len; } if (i) {