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Mon, 11 May 2020 11:05:17 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 789ADC433BA; Mon, 11 May 2020 11:05:16 +0000 (UTC) Received: from vjitta-linux.qualcomm.com (blr-c-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: vjitta) by smtp.codeaurora.org (Postfix) with ESMTPSA id 22866C433F2; Mon, 11 May 2020 11:05:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 22866C433F2 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=vjitta@codeaurora.org From: vjitta@codeaurora.org To: joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] iommu/iova: Retry from last rb tree node if iova search fails Date: Mon, 11 May 2020 16:34:53 +0530 Message-Id: <1589195093-17129-1-git-send-email-vjitta@codeaurora.org> X-Mailer: git-send-email 1.9.1 Cc: kernel-team@android.com, vinmenon@codeaurora.org, robin.murphy@arm.com, vjitta@codeaurora.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" From: Vijayanand Jitta When ever a new iova alloc request comes iova is always searched from the cached node and the nodes which are previous to cached node. So, even if there is free iova space available in the nodes which are next to the cached node iova allocation can still fail because of this approach. Consider the following sequence of iova alloc and frees on 1GB of iova space 1) alloc - 500MB 2) alloc - 12MB 3) alloc - 499MB 4) free - 12MB which was allocated in step 2 5) alloc - 13MB After the above sequence we will have 12MB of free iova space and cached node will be pointing to the iova pfn of last alloc of 13MB which will be the lowest iova pfn of that iova space. Now if we get an alloc request of 2MB we just search from cached node and then look for lower iova pfn's for free iova and as they aren't any, iova alloc fails though there is 12MB of free iova space. To avoid such iova search failures do a retry from the last rb tree node when iova search fails, this will search the entire tree and get an iova if its available Signed-off-by: Vijayanand Jitta --- drivers/iommu/iova.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 0e6a953..7d82afc 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -184,8 +184,9 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, struct rb_node *curr, *prev; struct iova *curr_iova; unsigned long flags; - unsigned long new_pfn; + unsigned long new_pfn, alloc_lo_new; unsigned long align_mask = ~0UL; + unsigned long alloc_hi = limit_pfn, alloc_lo = iovad->start_pfn; if (size_aligned) align_mask <<= fls_long(size - 1); @@ -198,15 +199,25 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, curr = __get_cached_rbnode(iovad, limit_pfn); curr_iova = rb_entry(curr, struct iova, node); + alloc_lo_new = curr_iova->pfn_hi; + +retry: do { - limit_pfn = min(limit_pfn, curr_iova->pfn_lo); - new_pfn = (limit_pfn - size) & align_mask; + alloc_hi = min(alloc_hi, curr_iova->pfn_lo); + new_pfn = (alloc_hi - size) & align_mask; prev = curr; curr = rb_prev(curr); curr_iova = rb_entry(curr, struct iova, node); } while (curr && new_pfn <= curr_iova->pfn_hi); - if (limit_pfn < size || new_pfn < iovad->start_pfn) { + if (alloc_hi < size || new_pfn < alloc_lo) { + if (alloc_lo == iovad->start_pfn && alloc_lo_new < limit_pfn) { + alloc_hi = limit_pfn; + alloc_lo = alloc_lo_new; + curr = &iovad->anchor.node; + curr_iova = rb_entry(curr, struct iova, node); + goto retry; + } iovad->max32_alloc_size = size; goto iova32_full; } -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation 1.9.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu