From: Florian Fainelli <f.fainelli@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <f.fainelli@gmail.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"open list:NETWORKING \[GENERAL\]" <netdev@vger.kernel.org>,
Vivien Didelot <vivien.didelot@gmail.com>,
"open list:DMA MAPPING HELPERS"
<iommu@lists.linux-foundation.org>,
"David S. Miller" <davem@davemloft.net>,
bcm-kernel-feedback-list@broadcom.com,
Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@lst.de>
Subject: [PATCH 2/2] swiotlb: Return consistent SWIOTLB segments/nr_tbl
Date: Tue, 11 Jun 2019 10:58:25 -0700 [thread overview]
Message-ID: <20190611175825.572-3-f.fainelli@gmail.com> (raw)
In-Reply-To: <20190611175825.572-1-f.fainelli@gmail.com>
With a specifically contrived memory layout where there is no physical
memory available to the kernel below the 4GB boundary, we will fail to
perform the initial swiotlb_init() call and set no_iotlb_memory to true.
There are drivers out there that call into swiotlb_nr_tbl() to determine
whether they can use the SWIOTLB. With the right DMA_BIT_MASK() value
for these drivers (say 64-bit), they won't ever need to hit
swiotlb_tbl_map_single() so this can go unoticed and we would be
possibly lying about those drivers.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
kernel/dma/swiotlb.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index b2b5c5df273c..e906ef2e6315 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -129,15 +129,17 @@ setup_io_tlb_npages(char *str)
}
early_param("swiotlb", setup_io_tlb_npages);
+static bool no_iotlb_memory;
+
unsigned long swiotlb_nr_tbl(void)
{
- return io_tlb_nslabs;
+ return unlikely(no_iotlb_memory) ? 0 : io_tlb_nslabs;
}
EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
unsigned int swiotlb_max_segment(void)
{
- return max_segment;
+ return unlikely(no_iotlb_memory) ? 0 : max_segment;
}
EXPORT_SYMBOL_GPL(swiotlb_max_segment);
@@ -160,8 +162,6 @@ unsigned long swiotlb_size_or_default(void)
return size ? size : (IO_TLB_DEFAULT_SIZE);
}
-static bool no_iotlb_memory;
-
void swiotlb_print_info(void)
{
unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
--
2.17.1
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next prev parent reply other threads:[~2019-06-11 17:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-11 17:58 [PATCH 0/2] swiotlb: Cleanup and consistency fix Florian Fainelli
2019-06-11 17:58 ` [PATCH 1/2] swiotlb: Group identical cleanup in swiotlb_cleanup() Florian Fainelli
2019-06-14 9:46 ` Christoph Hellwig
2019-06-11 17:58 ` Florian Fainelli [this message]
2019-06-14 9:47 ` [PATCH 2/2] swiotlb: Return consistent SWIOTLB segments/nr_tbl Christoph Hellwig
2019-06-11 18:48 ` [PATCH 0/2] swiotlb: Cleanup and consistency fix Konrad Rzeszutek Wilk
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