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From:   Petr Tesarik <petrtesarik@huaweicloud.com>
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Cc:     Roberto Sassu <roberto.sassu@huaweicloud.com>, petr@tesarici.cz
Subject: [PATCH v7 1/9] swiotlb: bail out of swiotlb_init_late() if swiotlb is already allocated
Date:   Tue,  1 Aug 2023 08:23:56 +0200
Message-Id: <2d7e1823e264aa1990899cc95736e78e1ec21084.1690871004.git.petr.tesarik.ext@huawei.com>
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From: Petr Tesarik <petr.tesarik.ext@huawei.com>

If swiotlb is allocated, immediately return 0, so callers do not have to
check io_tlb_default_mem.nslabs explicitly.

Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
---
 arch/arm/xen/mm.c    | 10 ++++------
 kernel/dma/swiotlb.c |  3 +++
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index 3d826c0b5fee..882cd70c7a2f 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -125,12 +125,10 @@ static int __init xen_mm_init(void)
 		return 0;
 
 	/* we can work with the default swiotlb */
-	if (!io_tlb_default_mem.nslabs) {
-		rc = swiotlb_init_late(swiotlb_size_or_default(),
-				       xen_swiotlb_gfp(), NULL);
-		if (rc < 0)
-			return rc;
-	}
+	rc = swiotlb_init_late(swiotlb_size_or_default(),
+			       xen_swiotlb_gfp(), NULL);
+	if (rc < 0)
+		return rc;
 
 	cflush.op = 0;
 	cflush.a.dev_bus_addr = 0;
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 1c0a49e6685a..ee57fd9949dc 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -384,6 +384,9 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask,
 	bool retried = false;
 	int rc = 0;
 
+	if (io_tlb_default_mem.nslabs)
+		return 0;
+
 	if (swiotlb_force_disable)
 		return 0;
 
-- 
2.25.1