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x86/dma/amd-gart: Stop resizing dma_debug_entry pool 

dma-debug is now capable of adding new entries to its pool on-demand if
the initial preallocation was insufficient, so the IOMMU_LEAK logic no
longer needs to explicitly change the pool size. This does lose it the
ability to save a couple of megabytes of RAM by reducing the pool size
below its default, but it seems unlikely that that is a realistic
concern these days (or indeed that anyone is actively debugging AGP
drivers' DMA usage any more). Getting rid of dma_debug_resize_entries()
will make room for further streamlining in the dma-debug code itself.

Removing the call reveals quite a lot of cruft which has been useless
for nearly a decade since commit 19c1a6f576 ("x86 gart: reimplement
IOMMU_LEAK feature by using DMA_API_DEBUG"), including the entire
'iommu=leak' parameter, which controlled nothing except whether
dma_debug_resize_entries() was called or not.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Robin Murphy 2018-12-10 14:00:31 +00:00 committed by Christoph Hellwig
parent ceb51173b2
commit a8a4c98fc9
2 changed files with 1 additions and 27 deletions
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5
Documentation/x86/x86_64/boot-options.txt
View File

@ -209,7 +209,7 @@ IOMMU (input/output memory management unit)
mapping with memory protection, etc.
Kernel boot message: "PCI-DMA: Using Calgary IOMMU"
iommu=[<size>][,noagp][,off][,force][,noforce][,leak[=<nr_of_leak_pages>]
iommu=[<size>][,noagp][,off][,force][,noforce]
[,memaper[=<order>]][,merge][,fullflush][,nomerge]
[,noaperture][,calgary]
@ -228,9 +228,6 @@ IOMMU (input/output memory management unit)
allowed Overwrite iommu off workarounds for specific chipsets.
fullflush Flush IOMMU on each allocation (default).
nofullflush Don't use IOMMU fullflush.
leak Turn on simple iommu leak tracing (only when
CONFIG_IOMMU_LEAK is on). Default number of leak pages
is 20.
memaper[=<order>] Allocate an own aperture over RAM with size 32MB<<order.
(default: order=1, i.e. 64MB)
merge Do scatter-gather (SG) merging. Implies "force"

23
arch/x86/kernel/amd_gart_64.c
View File

@ -151,9 +151,6 @@ static void flush_gart(void)
#ifdef CONFIG_IOMMU_LEAK
/* Debugging aid for drivers that don't free their IOMMU tables */
static int leak_trace;
static int iommu_leak_pages = 20;
static void dump_leak(void)
{
static int dump;
@ -755,16 +752,6 @@ int __init gart_iommu_init(void)
if (!iommu_gart_bitmap)
panic("Cannot allocate iommu bitmap\n");
#ifdef CONFIG_IOMMU_LEAK
if (leak_trace) {
int ret;
ret = dma_debug_resize_entries(iommu_pages);
if (ret)
pr_debug("PCI-DMA: Cannot trace all the entries\n");
}
#endif
pr_info("PCI-DMA: Reserving %luMB of IOMMU area in the AGP aperture\n",
iommu_size >> 20);
@ -825,16 +812,6 @@ void __init gart_parse_options(char *p)
{
int arg;
#ifdef CONFIG_IOMMU_LEAK
if (!strncmp(p, "leak", 4)) {
leak_trace = 1;
p += 4;
if (*p == '=')
++p;
if (isdigit(*p) && get_option(&p, &arg))
iommu_leak_pages = arg;
}
#endif
if (isdigit(*p) && get_option(&p, &arg))
iommu_size = arg;
if (!strncmp(p, "fullflush", 9))