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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>,
	linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 3/4] powerpc/pseries/iommu: Use a locallock instead local_irq_save()
Date: Wed, 27 Mar 2019 19:33:09 +0100	[thread overview]
Message-ID: <20190327183310.1015-3-bigeasy@linutronix.de> (raw)
In-Reply-To: <20190327183310.1015-1-bigeasy@linutronix.de>

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


  parent reply	other threads:[~2019-03-27 18:33 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-20 17:15 [ANNOUNCE] v5.0.3-rt1 Sebastian Andrzej Siewior
2019-03-22 18:52 ` Julien Grall
2019-03-25  8:13   ` John Ogness
2019-03-25 10:18     ` Julien Grall
2019-03-25 10:34       ` John Ogness
2019-03-26 10:26         ` Julien Grall
2019-03-26 16:04           ` John Ogness
2019-03-27 18:33 ` [PATCH 1/4] printk: An all-in-one commit to fix build failures Sebastian Andrzej Siewior
2019-03-27 18:33   ` [PATCH 2/4] powerpc/stackprotector: work around stack-guard init from atomic Sebastian Andrzej Siewior
2019-05-10 21:46     ` Steven Rostedt
2019-03-27 18:33   ` Sebastian Andrzej Siewior [this message]
2019-03-27 18:33   ` [PATCH 4/4] powerpc: reshuffle TIF bits Sebastian Andrzej Siewior

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