linux-kernel - [PATCH v1] swiotlb: move slot allocation explanation comment where it belongs

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Message-Id: <20230802163034.1410-1-petrtesarik@huaweicloud.com>
Date:   Wed,  2 Aug 2023 18:30:34 +0200
From:   Petr Tesarik <petrtesarik@...weicloud.com>
To:     Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Jianxiong Gao <jxgao@...gle.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        iommu@...ts.linux.dev (open list:DMA MAPPING HELPERS),
        linux-kernel@...r.kernel.org (open list)
Cc:     Roberto Sassu <roberto.sassu@...weicloud.com>, petr@...arici.cz
Subject: [PATCH v1] swiotlb: move slot allocation explanation comment where it belongs

From: Petr Tesarik <petr.tesarik.ext@...wei.com>

Move the comment down in front of the loop that actually sets the list
member of struct io_tlb_slot to zero.

Fixes: 26a7e094783d ("swiotlb: refactor swiotlb_tbl_map_single")
Signed-off-by: Petr Tesarik <petr.tesarik.ext@...wei.com>
---
 kernel/dma/swiotlb.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index d7eac84f975b..50a0e9c45c39 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -1018,11 +1018,6 @@ static int swiotlb_area_find_slots(struct device *dev, struct io_tlb_pool *pool,
 			continue;
 		}
 
-		/*
-		 * If we find a slot that indicates we have 'nslots' number of
-		 * contiguous buffers, we allocate the buffers from that slot
-		 * and mark the entries as '0' indicating unavailable.
-		 */
 		if (!iommu_is_span_boundary(slot_index, nslots,
 					    nr_slots(tbl_dma_addr),
 					    max_slots)) {
@@ -1038,6 +1033,11 @@ static int swiotlb_area_find_slots(struct device *dev, struct io_tlb_pool *pool,
 	return -1;
 
 found:
+	/*
+	 * If we find a slot that indicates we have 'nslots' number of
+	 * contiguous buffers, we allocate the buffers from that slot onwards
+	 * and set the list of free entries to '0' indicating unavailable.
+	 */
 	for (i = slot_index; i < slot_index + nslots; i++) {
 		pool->slots[i].list = 0;
 		pool->slots[i].alloc_size = alloc_size - (offset +
-- 
2.25.1