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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Tue, 26 Mar 2019 18:31:54 +0100
Subject: [PATCH] powerpc/pseries/iommu: Use a locallock instead
local_irq_save()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.3-rt1.tar.xz
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>
---
arch/powerpc/platforms/pseries/iommu.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -24,6 +24,7 @@
#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>
@@ -178,6 +179,7 @@ static int tce_build_pSeriesLP(struct io
}
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,
@@ -198,7 +200,8 @@ static int tce_buildmulti_pSeriesLP(stru
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);
@@ -209,7 +212,7 @@ static int tce_buildmulti_pSeriesLP(stru
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);
}
@@ -243,7 +246,7 @@ static int tce_buildmulti_pSeriesLP(stru
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;
@@ -401,13 +404,14 @@ static int tce_setrange_multi_pSeriesLP(
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);
@@ -453,7 +457,7 @@ static int tce_setrange_multi_pSeriesLP(
/* error cleanup: caller will clear whole range */
- local_irq_enable();
+ local_unlock_irq(tcp_page_lock);
return rc;
}
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