Merge branch 'core/irq_work' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into irq/core

irq_work fixes and cleanups, in preparation for full dyntics support.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

16 files changed, 15 insertions, 24 deletions

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 9d5904cc7712..9b504af2e966 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -5,7 +5,6 @@ config ALPHA
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_SYSCALL_WRAPPERS
-	select HAVE_IRQ_WORK
 	select HAVE_PCSPKR_PLATFORM
 	select HAVE_PERF_EVENTS
 	select HAVE_DMA_ATTRS
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 67874b82a4ed..9bbe760f2352 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -36,7 +36,6 @@ config ARM
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_HW_BREAKPOINT if (PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7))
 	select HAVE_IDE if PCI || ISA || PCMCIA
-	select HAVE_IRQ_WORK
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZMA
 	select HAVE_KERNEL_LZO
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f8f362aafee9..75e915b72471 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -21,7 +21,6 @@ config ARM64
 	select HAVE_GENERIC_DMA_COHERENT
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_HW_BREAKPOINT if PERF_EVENTS
-	select HAVE_IRQ_WORK
 	select HAVE_MEMBLOCK
 	select HAVE_PERF_EVENTS
 	select IRQ_DOMAIN
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index b6f3ad5441c5..86f891f0ae48 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -24,7 +24,6 @@ config BLACKFIN
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	select HAVE_IDE
-	select HAVE_IRQ_WORK
 	select HAVE_KERNEL_GZIP if RAMKERNEL
 	select HAVE_KERNEL_BZIP2 if RAMKERNEL
 	select HAVE_KERNEL_LZMA if RAMKERNEL
diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index 9d262645f667..17df48fc8f44 100644
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -3,7 +3,6 @@ config FRV
 	default y
 	select HAVE_IDE
 	select HAVE_ARCH_TRACEHOOK
-	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
 	select HAVE_UID16
 	select HAVE_GENERIC_HARDIRQS
diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig
index 0744f7d7b1fd..40a318594ae7 100644
--- a/arch/hexagon/Kconfig
+++ b/arch/hexagon/Kconfig
@@ -14,7 +14,6 @@ config HEXAGON
 	# select HAVE_CLK
 	# select IRQ_PER_CPU
 	# select GENERIC_PENDING_IRQ if SMP
-	select HAVE_IRQ_WORK
 	select GENERIC_ATOMIC64
 	select HAVE_PERF_EVENTS
 	select HAVE_GENERIC_HARDIRQS
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 2ac626ab9d43..121ed51ac227 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -4,7 +4,6 @@ config MIPS
 	select HAVE_GENERIC_DMA_COHERENT
 	select HAVE_IDE
 	select HAVE_OPROFILE
-	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
 	select PERF_USE_VMALLOC
 	select HAVE_ARCH_KGDB
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index b77feffbadea..9dd5c1888878 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -9,7 +9,6 @@ config PARISC
 	select RTC_DRV_GENERIC
 	select INIT_ALL_POSSIBLE
 	select BUG
-	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
 	select GENERIC_ATOMIC64 if !64BIT
 	select HAVE_GENERIC_HARDIRQS
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 17903f1f356b..d45edca88b57 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -118,7 +118,6 @@ config PPC
 	select HAVE_SYSCALL_WRAPPERS if PPC64
 	select GENERIC_ATOMIC64 if PPC32
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
-	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_HW_BREAKPOINT if PERF_EVENTS && PPC_BOOK3S_64
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b5ea38c25647..c15ba7d1be64 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -78,7 +78,6 @@ config S390
 	select HAVE_KVM if 64BIT
 	select HAVE_ARCH_TRACEHOOK
 	select INIT_ALL_POSSIBLE
-	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select HAVE_DEBUG_KMEMLEAK
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index babc2b826c5c..996e008aaa3e 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -11,7 +11,6 @@ config SUPERH
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_ATTRS
-	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
 	select ARCH_HAVE_CUSTOM_GPIO_H
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 9f2edb5c5551..ed937ae72df3 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -23,7 +23,6 @@ config SPARC
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select RTC_CLASS
 	select RTC_DRV_M48T59
-	select HAVE_IRQ_WORK
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_API_DEBUG
 	select HAVE_ARCH_JUMP_LABEL
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 79795af59810..5d3d61f40b31 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -28,7 +28,6 @@ config X86
 	select HAVE_OPROFILE
 	select HAVE_PCSPKR_PLATFORM
 	select HAVE_PERF_EVENTS
-	select HAVE_IRQ_WORK
 	select HAVE_IOREMAP_PROT
 	select HAVE_KPROBES
 	select HAVE_MEMBLOCK
diff --git a/drivers/staging/iio/trigger/Kconfig b/drivers/staging/iio/trigger/Kconfig
index 7d3207559265..d44d3ad26fa5 100644
--- a/drivers/staging/iio/trigger/Kconfig
+++ b/drivers/staging/iio/trigger/Kconfig
@@ -21,7 +21,6 @@ config IIO_GPIO_TRIGGER
 config IIO_SYSFS_TRIGGER
 	tristate "SYSFS trigger"
 	depends on SYSFS
-	depends on HAVE_IRQ_WORK
 	select IRQ_WORK
 	help
 	  Provides support for using SYSFS entry as IIO triggers.
diff --git a/init/Kconfig b/init/Kconfig
index be8b7f55312d..e3227d7ba35d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -20,12 +20,8 @@ config CONSTRUCTORS
 	bool
 	depends on !UML
 
-config HAVE_IRQ_WORK
-	bool
-
 config IRQ_WORK
 	bool
-	depends on HAVE_IRQ_WORK
 
 config BUILDTIME_EXTABLE_SORT
 	bool
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 1588e3b2871b..64eddd59ed83 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -34,15 +34,21 @@ static DEFINE_PER_CPU(struct llist_head, irq_work_list);
  */
 static bool irq_work_claim(struct irq_work *work)
 {
-	unsigned long flags, nflags;
+	unsigned long flags, oflags, nflags;
 
+	/*
+	 * Start with our best wish as a premise but only trust any
+	 * flag value after cmpxchg() result.
+	 */
+	flags = work->flags & ~IRQ_WORK_PENDING;
 	for (;;) {
-		flags = work->flags;
-		if (flags & IRQ_WORK_PENDING)
-			return false;
 		nflags = flags | IRQ_WORK_FLAGS;
-		if (cmpxchg(&work->flags, flags, nflags) == flags)
+		oflags = cmpxchg(&work->flags, flags, nflags);
+		if (oflags == flags)
 			break;
+		if (oflags & IRQ_WORK_PENDING)
+			return false;
+		flags = oflags;
 		cpu_relax();
 	}
 
@@ -119,8 +125,11 @@ void irq_work_run(void)
 		/*
 		 * Clear the PENDING bit, after this point the @work
 		 * can be re-used.
+		 * Make it immediately visible so that other CPUs trying
+		 * to claim that work don't rely on us to handle their data
+		 * while we are in the middle of the func.
 		 */
-		work->flags = IRQ_WORK_BUSY;
+		xchg(&work->flags, IRQ_WORK_BUSY);
 		work->func(work);
 		/*
 		 * Clear the BUSY bit and return to the free state if