From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751137AbdEBQYD (ORCPT ); Tue, 2 May 2017 12:24:03 -0400 Received: from foss.arm.com ([217.140.101.70]:46460 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750769AbdEBQX6 (ORCPT ); Tue, 2 May 2017 12:23:58 -0400 From: Marc Zyngier To: Shanker Donthineni Cc: linux-kernel , linux-arm-kernel , Thomas Gleixner , Jason Cooper , Vikram Sethi Subject: Re: [PATCH v4] irqchip/gicv3-its: Avoid memory over allocation for ITEs In-Reply-To: <1493562975-14365-1-git-send-email-shankerd@codeaurora.org> (Shanker Donthineni's message of "Sun, 30 Apr 2017 09:36:15 -0500") Organization: ARM Ltd References: <1493562975-14365-1-git-send-email-shankerd@codeaurora.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) Date: Tue, 02 May 2017 17:16:32 +0100 Message-ID: <87lgqfmdy7.fsf@on-the-bus.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 30 2017 at 3:36:15 pm BST, Shanker Donthineni wrote: > We are always allocating extra 255Bytes of memory to handle ITE > physical address alignment requirement. The kmalloc() satisfies > the ITE alignment since the ITS driver is requesting a minimum > size of ITS_ITT_ALIGN bytes. > > Let's try to allocate the exact amount of memory that is required > for ITEs to avoid wastage. > > Signed-off-by: Shanker Donthineni > --- > Changes: > v2: removed 'Change-Id: Ia8084189833f2081ff13c392deb5070c46a64038' from commit. > v3: changed from IITE to ITE. > v3: removed fallback since kmalloc() guarantees the right alignment. > > drivers/irqchip/irq-gic-v3-its.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > index 45ea1933..72e56f03 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -261,7 +261,6 @@ static struct its_collection *its_build_mapd_cmd(struct its_cmd_block *cmd, > u8 size = ilog2(desc->its_mapd_cmd.dev->nr_ites); > > itt_addr = virt_to_phys(desc->its_mapd_cmd.dev->itt); > - itt_addr = ALIGN(itt_addr, ITS_ITT_ALIGN); > > its_encode_cmd(cmd, GITS_CMD_MAPD); > its_encode_devid(cmd, desc->its_mapd_cmd.dev->device_id); > @@ -1329,13 +1328,14 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id, > */ > nr_ites = max(2UL, roundup_pow_of_two(nvecs)); > sz = nr_ites * its->ite_size; > - sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1; > + sz = max(sz, ITS_ITT_ALIGN); > itt = kzalloc(sz, GFP_KERNEL); > lpi_map = its_lpi_alloc_chunks(nvecs, &lpi_base, &nr_lpis); > if (lpi_map) > col_map = kzalloc(sizeof(*col_map) * nr_lpis, GFP_KERNEL); > > - if (!dev || !itt || !lpi_map || !col_map) { > + if (!dev || !itt || !lpi_map || !col_map || > + !IS_ALIGNED(virt_to_phys(itt), ITS_ITT_ALIGN)) { > kfree(dev); > kfree(itt); > kfree(lpi_map); I'm confused. Either the alignment is guaranteed (and you should document why it is so), or it is not, and we need to handle the non-alignment (instead of failing). Thanks, M. -- Jazz is not dead, it just smell funny.