[PATCH v7 1/9] swiotlb: bail out of swiotlb_init_late() if swiotlb is already allocated

[Petr Tesarik <petrtesarik@xxxxxxxxxxxxxxx>]

From: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>

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@xxxxxxxxxx>
---
 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