From: Petr Tesarik <petrtesarik@huaweicloud.com>
To: Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
Petr Tesarik <petr.tesarik1@huawei-partners.com>,
Michael Kelley <mhklinux@outlook.com>,
Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org (open list),
iommu@lists.linux.dev (open list:DMA MAPPING HELPERS)
Cc: Roberto Sassu <roberto.sassu@huaweicloud.com>,
Petr Tesarik <petr@tesarici.cz>
Subject: [PATCH v4 2/2] bug: introduce ASSERT_VAR_CAN_HOLD()
Date: Mon, 25 Mar 2024 09:31:05 +0100 [thread overview]
Message-ID: <20240325083105.658-3-petrtesarik@huaweicloud.com> (raw)
In-Reply-To: <20240325083105.658-1-petrtesarik@huaweicloud.com>
From: Petr Tesarik <petr.tesarik1@huawei-partners.com>
Introduce an ASSERT_VAR_CAN_HOLD() macro to check at build time that a
variable can hold the given value.
Use this macro in swiotlb to make sure that the list and pad_slots fields
of struct io_tlb_slot are big enough to hold the maximum possible value of
IO_TLB_SEGSIZE.
Signed-off-by: Petr Tesarik <petr.tesarik1@huawei-partners.com>
---
include/linux/build_bug.h | 10 ++++++++++
kernel/dma/swiotlb.c | 2 ++
2 files changed, 12 insertions(+)
diff --git a/include/linux/build_bug.h b/include/linux/build_bug.h
index 3aa3640f8c18..6e2486508af0 100644
--- a/include/linux/build_bug.h
+++ b/include/linux/build_bug.h
@@ -86,4 +86,14 @@
"Offset of " #field " in " #type " has changed.")
+/*
+ * Compile time check that a variable can hold the given value
+ */
+#define ASSERT_VAR_CAN_HOLD(var, value) ({ \
+ typeof(value) __val = (value); \
+ typeof(var) __tmp = __val; \
+ BUILD_BUG_ON_MSG(__tmp != __val, \
+ #var " cannot hold " #value "."); \
+})
+
#endif /* _LINUX_BUILD_BUG_H */
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index d7a8cb93ef2d..a34ea2c35446 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -285,6 +285,8 @@ static void swiotlb_init_io_tlb_pool(struct io_tlb_pool *mem, phys_addr_t start,
mem->areas[i].used = 0;
}
+ ASSERT_VAR_CAN_HOLD(mem->slots[0].list, IO_TLB_SEGSIZE);
+ ASSERT_VAR_CAN_HOLD(mem->slots[0].pad_slots, IO_TLB_SEGSIZE);
for (i = 0; i < mem->nslabs; i++) {
mem->slots[i].list = min(IO_TLB_SEGSIZE - io_tlb_offset(i),
mem->nslabs - i);
--
2.34.1
next prev parent reply other threads:[~2024-03-25 8:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-25 8:31 [PATCH v4 0/2] swiotlb: allocate padding slots if necessary Petr Tesarik
2024-03-25 8:31 ` [PATCH v4 1/2] swiotlb: extend buffer pre-padding to alloc_align_mask " Petr Tesarik
2024-03-25 19:16 ` Michael Kelley
2024-04-02 15:10 ` Christoph Hellwig
2024-03-25 8:31 ` Petr Tesarik [this message]
2024-03-26 7:56 ` [PATCH v4 2/2] bug: introduce ASSERT_VAR_CAN_HOLD() Christoph Hellwig
2024-03-26 11:55 ` Petr Tesařík
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