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Subject[PATCH 3/4] powerpc/pseries/iommu: Use a locallock instead local_irq_save()
Date
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().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/powerpc/platforms/pseries/iommu.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 8fc8fe0b98485..14ecedbd8ff12 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -38,6 +38,7 @@
#include <linux/of.h>
#include <linux/iommu.h>
#include <linux/rculist.h>
+#include <linux/locallock.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/rtas.h>
@@ -191,6 +192,7 @@ static int tce_build_pSeriesLP(struct iommu_table *tbl, long tcenum,
}

static DEFINE_PER_CPU(__be64 *, tce_page);
+static DEFINE_LOCAL_IRQ_LOCK(tcp_page_lock);

static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
long npages, unsigned long uaddr,
@@ -211,7 +213,8 @@ 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(tcp_page_lock, flags);

tcep = __this_cpu_read(tce_page);

@@ -222,7 +225,7 @@ 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(tcp_page_lock, flags);
return tce_build_pSeriesLP(tbl, tcenum, npages, uaddr,
direction, attrs);
}
@@ -256,7 +259,7 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
tcenum += limit;
} while (npages > 0 && !rc);

- local_irq_restore(flags);
+ local_unlock_irqrestore(tcp_page_lock, flags);

if (unlikely(rc == H_NOT_ENOUGH_RESOURCES)) {
ret = (int)rc;
@@ -414,13 +417,14 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
u64 rc = 0;
long l, limit;

- local_irq_disable(); /* to protect tcep and the page behind it */
+ /* to protect tcep and the page behind it */
+ local_lock_irq(tcp_page_lock);
tcep = __this_cpu_read(tce_page);

if (!tcep) {
tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
if (!tcep) {
- local_irq_enable();
+ local_unlock_irq(tcp_page_lock);
return -ENOMEM;
}
__this_cpu_write(tce_page, tcep);
@@ -466,7 +470,7 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,

/* error cleanup: caller will clear whole range */

- local_irq_enable();
+ local_unlock_irq(tcp_page_lock);
return rc;
}

--
2.20.1
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