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powerpc/pseries/iommu: Use a locallock instead local_irq_save()

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BugLink: https://bugs.launchpad.net/bugs/2060704

The locallock protects the per-CPU variable tce_page. The function
attempts to allocate memory while tce_page is protected (by disabling
interrupts).

Use local_irq_save() instead of local_irq_disable().

Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kevin Becker <kevin.becker@canonical.com>
This commit is contained in:
Sebastian Andrzej Siewior
2019-03-26 18:31:54 +01:00
committed by Kevin Becker
parent 3d73855a12
commit dda9580f0d
1 changed files with 20 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/powerpc/platforms/pseries/iommu.c
+20 -11
View File
@@ -25,6 +25,7 @@
#include <linux/of_address.h>
#include <linux/iommu.h>
#include <linux/rculist.h>
#include <linux/local_lock.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/rtas.h>
@@ -206,7 +207,13 @@ static int tce_build_pSeriesLP(unsigned long liobn, long tcenum, long tceshift,
return ret;
}
static DEFINE_PER_CPU(__be64 *, tce_page);
struct tce_page {
__be64 * page;
local_lock_t lock;
};
static DEFINE_PER_CPU(struct tce_page, tce_page) = {
.lock = INIT_LOCAL_LOCK(lock),
};
static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
long npages, unsigned long uaddr,
@@ -229,9 +236,10 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
direction, attrs);
}
local_irq_save(flags); /* to protect tcep and the page behind it */
/* to protect tcep and the page behind it */
local_lock_irqsave(&tce_page.lock, flags);
tcep = __this_cpu_read(tce_page);
tcep = __this_cpu_read(tce_page.page);
/* This is safe to do since interrupts are off when we're called
* from iommu_alloc{,_sg}()
@@ -240,12 +248,12 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
/* If allocation fails, fall back to the loop implementation */
if (!tcep) {
local_irq_restore(flags);
local_unlock_irqrestore(&tce_page.lock, flags);
return tce_build_pSeriesLP(tbl->it_index, tcenum,
tceshift,
npages, uaddr, direction, attrs);
}
__this_cpu_write(tce_page, tcep);
__this_cpu_write(tce_page.page, tcep);
}
rpn = __pa(uaddr) >> tceshift;
@@ -275,7 +283,7 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
tcenum += limit;
} while (npages > 0 && !rc);
local_irq_restore(flags);
local_unlock_irqrestore(&tce_page.lock, flags);
if (unlikely(rc == H_NOT_ENOUGH_RESOURCES)) {
ret = (int)rc;
@@ -459,16 +467,17 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
DMA_BIDIRECTIONAL, 0);
}
local_irq_disable(); /* to protect tcep and the page behind it */
tcep = __this_cpu_read(tce_page);
/* to protect tcep and the page behind it */
local_lock_irq(&tce_page.lock);
tcep = __this_cpu_read(tce_page.page);
if (!tcep) {
tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
if (!tcep) {
local_irq_enable();
local_unlock_irq(&tce_page.lock);
return -ENOMEM;
}
__this_cpu_write(tce_page, tcep);
__this_cpu_write(tce_page.page, tcep);
}
proto_tce = TCE_PCI_READ | TCE_PCI_WRITE;
@@ -511,7 +520,7 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
/* error cleanup: caller will clear whole range */
local_irq_enable();
local_unlock_irq(&tce_page.lock);
return rc;
}