[PATCH v5 2/6] dma: swiotlb: Track whether the pool size was explicitly set
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COLD17d
From: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>
Date: 2026-09-21 06:37:30
Also in:
linux-arm-kernel, linux-iommu, linux-mips, linux-riscv, linux-s390, lkml, loongarch
Subsystem:
dma mapping helpers, the rest · Maintainers:
Marek Szyprowski, Linus Torvalds
Revision v5 of 4 in this series.
Revisions (4)
- v3 [diff vs current]
- v4 [diff vs current]
- v5 current
- v6 [diff vs current]
swiotlb_adjust_size() must not override a pool size supplied through the swiotlb= command-line parameter. Currently, it determines whether a size was supplied by comparing default_nslabs with IO_TLB_DEFAULT_SIZE. This fails when the user explicitly requests the compiled-in default size, allowing the request to be overwritten by automatic pool sizing. Record whether swiotlb= supplied a numeric size and add swiotlb_default_size_changed() to query that state. Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org> --- kernel/dma/swiotlb.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index aa19e81ae544..8f86deb25be2 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c@@ -107,6 +107,7 @@ static struct io_tlb_mem io_tlb_default_mem; static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT; static unsigned long default_nareas; +static bool swiotlb_size_set __initdata; /** * struct io_tlb_area - IO TLB memory area descriptor
@@ -269,6 +270,7 @@ setup_io_tlb_npages(char *str) /* avoid tail segment of size < IO_TLB_SEGSIZE */ default_nslabs = ALIGN(simple_strtoul(str, &str, 0), IO_TLB_SEGSIZE); + swiotlb_size_set = true; } if (*str == ',') ++str;
@@ -304,6 +306,11 @@ unsigned long swiotlb_size_or_default(void) return default_nslabs << IO_TLB_SHIFT; } +static bool __init swiotlb_default_size_changed(void) +{ + return swiotlb_size_set; +} + void __init swiotlb_adjust_size(unsigned long size) { /*
@@ -311,7 +318,7 @@ void __init swiotlb_adjust_size(unsigned long size) * architectures such as those supporting memory encryption to * adjust/expand SWIOTLB size for their use. */ - if (default_nslabs != IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT) + if (swiotlb_default_size_changed()) return; default_nslabs = swiotlb_aligned_nslabs(size);
--
2.43.0