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From: Finn Thain <fthain@telegraphics.com.au>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
	Russell King <linux@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Stephen N Chivers <schivers@csc.com.au>,
	Thomas Gleixner <tglx@linutronix.de>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	John Stultz <john.stultz@linaro.org>,
	linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH 01/13] arm: Fix mutual exclusion in arch_gettimeoffset
Date: Mon, 12 Nov 2018 15:12:39 +1100
Message-ID: <d1559db8eddb5b06747b152ae69b63c3aa66ed09.1541995959.git.fthain@telegraphics.com.au> (raw)
In-Reply-To: <cover.1541995959.git.fthain@telegraphics.com.au>

Implementations of arch_gettimeoffset are generally not re-entrant
and assume that interrupts have been disabled. Unfortunately this
pre-condition got broken in v2.6.32.

Fixes: 5cfc8ee0bb51 ("ARM: convert arm to arch_gettimeoffset()")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 arch/arm/mach-ebsa110/core.c | 5 +++++
 arch/arm/mach-rpc/time.c     | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/arch/arm/mach-ebsa110/core.c b/arch/arm/mach-ebsa110/core.c
index 688e5fed49a7..479f89a1accf 100644
--- a/arch/arm/mach-ebsa110/core.c
+++ b/arch/arm/mach-ebsa110/core.c
@@ -160,12 +160,17 @@ static void __init ebsa110_init_early(void)
  */
 static u32 ebsa110_gettimeoffset(void)
 {
+	unsigned long flags;
 	unsigned long offset, count;
 
+	local_irq_save(flags);
+
 	__raw_writeb(0x40, PIT_CTRL);
 	count = __raw_readb(PIT_T1);
 	count |= __raw_readb(PIT_T1) << 8;
 
+	local_irq_restore(flags);
+
 	/*
 	 * If count > COUNT, make the number negative.
 	 */
diff --git a/arch/arm/mach-rpc/time.c b/arch/arm/mach-rpc/time.c
index 2689771c1d38..852bb3801638 100644
--- a/arch/arm/mach-rpc/time.c
+++ b/arch/arm/mach-rpc/time.c
@@ -29,9 +29,12 @@
 
 static u32 ioc_timer_gettimeoffset(void)
 {
+	unsigned long flags;
 	unsigned int count1, count2, status;
 	long offset;
 
+	local_irq_save(flags);
+
 	ioc_writeb (0, IOC_T0LATCH);
 	barrier ();
 	count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
@@ -42,6 +45,8 @@ static u32 ioc_timer_gettimeoffset(void)
 	barrier ();
 	count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
 
+	local_irq_restore(flags);
+
 	offset = count2;
 	if (count2 < count1) {
 		/*
-- 
2.18.1


  parent reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-12  4:12 [RFC PATCH 00/13] m68k: Drop arch_gettimeoffset and adopt clocksource API Finn Thain
2018-11-12  4:12 ` [RFC PATCH 08/13] m68k: atari: Convert to " Finn Thain
2018-11-12  4:12 ` [RFC PATCH 04/13] m68k: mac: Clean up unused timer definitions Finn Thain
2018-11-12  4:12 ` [RFC PATCH 10/13] m68k: hp300: Convert to clocksource API Finn Thain
2018-11-12  4:12 ` [RFC PATCH 11/13] m68k: mac: " Finn Thain
2018-11-12  4:12 ` Finn Thain [this message]
2018-11-12  8:34   ` [RFC PATCH 01/13] arm: Fix mutual exclusion in arch_gettimeoffset Christoph Hellwig
2018-11-13  3:39     ` Finn Thain
2018-11-13  9:20       ` Russell King - ARM Linux
2018-11-13 21:55         ` Finn Thain
2018-11-13 23:43           ` Russell King - ARM Linux
2018-11-14  1:35             ` Michael Schmitz
2018-11-14  7:58               ` Russell King - ARM Linux
2018-11-15  1:34                 ` Michael Schmitz
2018-11-14  3:17             ` Finn Thain
2018-11-14 14:16               ` Russell King - ARM Linux
2018-11-14 14:58                 ` Geert Uytterhoeven
2018-11-14 18:11                   ` Russell King - ARM Linux
2018-11-15  4:12                 ` Finn Thain
2018-11-16 17:47                   ` Russell King - ARM Linux
2018-11-16 22:49                     ` Finn Thain
2018-11-17  3:00                       ` Michael Schmitz
2018-11-14 12:05   ` Russell King - ARM Linux
2018-11-12  4:12 ` [RFC PATCH 02/13] m68k: " Finn Thain
2018-11-12  4:12 ` [RFC PATCH 07/13] m68k: amiga: Convert to clocksource API Finn Thain
2018-11-12  9:02   ` Geert Uytterhoeven
2018-11-12  9:21     ` Finn Thain
2018-11-12  4:12 ` [RFC PATCH 09/13] m68k: bvme6000: " Finn Thain
2018-11-12  4:12 ` [RFC PATCH 06/13] m68k: Drop ARCH_USES_GETTIMEOFFSET Finn Thain
2018-11-12  9:00   ` Geert Uytterhoeven
2018-11-12  9:06     ` Finn Thain
2018-11-13  2:29       ` Michael Schmitz
2018-11-13  3:14         ` Finn Thain
2018-11-13  4:50           ` Michael Schmitz
2018-11-13  6:15             ` Finn Thain
2018-11-13  8:24               ` Michael Schmitz
2018-11-13 22:11                 ` Finn Thain
2018-11-14  1:08                   ` Michael Schmitz
2018-11-14  2:58                     ` Michael Schmitz
2018-11-14 23:54                       ` Michael Schmitz
2018-11-15  4:37                         ` Finn Thain
2018-11-15  6:35                         ` Michael Schmitz
2018-11-16  0:04                           ` Finn Thain
2018-11-12  4:12 ` [RFC PATCH 13/13] m68k: mvme16x: Convert to clocksource API Finn Thain
2018-11-12 18:37   ` Thomas Gleixner
2018-11-13  0:11     ` Finn Thain
2018-11-13 22:04       ` Finn Thain
2018-11-13 22:10         ` [RFC PATCH 13/13] m68k: mvme16x: Convert to clocksource APIy Thomas Gleixner
2018-11-13 22:33           ` Finn Thain
2018-11-18 17:12             ` Thomas Gleixner
2018-11-12  4:12 ` [RFC PATCH 03/13] m68k: mac: Fix VIA timer counter accesses Finn Thain
2018-11-12  4:12 ` [RFC PATCH 12/13] m68k: mvme147: Convert to clocksource API Finn Thain
2018-11-12  4:12 ` [RFC PATCH 05/13] m68k: apollo, q40, sun3, sun3x: Remove arch_gettimeoffset implementations Finn Thain

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