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path: root/arch/arm/include/asm/spinlock.h
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2013-01-28ARM: 7632/1: spinlock: avoid exclusive accesses on unlock() pathWill Deacon
When unlocking a spinlock, all we need to do is increment the owner field of the lock. Since only one CPU can be performing an unlock() operation for a given lock, this doesn't need to be exclusive. This patch simplifies arch_spin_unlock to use non-exclusive accesses when updating the owner field of the lock. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-07-09ARM: 7447/1: rwlocks: remove unused branch labels from trylock routinesWill Deacon
The ARM arch_{read,write}_trylock implementations include unused backwards branch labels, since we don't retry the locking operation if the exclusive store fails. This patch removes the labels. Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-07-09ARM: 7446/1: spinlock: use ticket algorithm for ARMv6+ locking implementationWill Deacon
Ticket spinlocks ensure locking fairness by introducing a FIFO-like nature to the granting of lock acquisitions and also reducing the thundering herd effect when spinning on a lock by allowing the cacheline to remain in a shared state amongst the waiting CPUs. This is especially important on systems where memory-access times are not necessarily uniform when accessing the lock structure (for example, on a multi-cluster platform where the lock is allocated into L1 when a CPU releases it). This patch implements the ticket spinlock algorithm for ARM, replacing the simpler implementation for ARMv6+ processors. Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-05-23ARM: 6939/1: fix missing 'cpu_relax()' declarationMarc Zyngier
ARM build fails with the following symptom: CC arch/arm/kernel/asm-offsets.s In file included from include/linux/seqlock.h:29, from include/linux/time.h:8, from include/linux/timex.h:56, from include/linux/sched.h:57, from arch/arm/kernel/asm-offsets.c:13: include/linux/spinlock.h: In function 'spin_unlock_wait': include/linux/spinlock.h:360: error: implicit declaration of function 'cpu_relax' make[1]: *** [arch/arm/kernel/asm-offsets.s] Error 1 Fix it by including <asm/processor.h>. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-10ARM: 6655/1: Correct WFE() in asm/spinlock.h for Thumb-2Dave Martin
The content for ALT_SMP() in the definition of WFE() expands to 6 bytes (IT cc ; WFEcc.W), which breaks the assumptions of the fixup code, leading to lockups when the affected code gets run. This patch works around the problem by explicitly using an IT + WFEcc.N pair. Signed-off-by: Dave Martin <dave.martin@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-02ARM: v6k: remove CPU_32v6K dependencies in asm/spinlock.hRussell King
SMP requires at least the ARMv6K extensions to be present, so if we're running on SMP, the WFE and SEV instructions must be available. However, when we run on UP, the v6K extensions may not be available, and so we don't want WFE/SEV to be in the instruction stream. Use the SMP alternatives infrastructure to replace these instructions with NOPs if we build for SMP but run on UP. Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Sourav Poddar <sourav.poddar@ti.com> Tested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-02-15ARM: 5897/1: spinlock: don't use deprecated barriers on ARMv7Rabin Vincent
On ARMv7, the use of the cp15 operations for barriers is deprecated in favour of the isb, dsb, and dmb instructions. Change the locking functions to use the appropriate type of dsb for the architecture being built for. Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-12-14locking: Convert raw_rwlock functions to arch_rwlockThomas Gleixner
Name space cleanup for rwlock functions. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: linux-arch@vger.kernel.org
2009-12-14locking: Convert raw_rwlock to arch_rwlockThomas Gleixner
Not strictly necessary for -rt as -rt does not have non sleeping rwlocks, but it's odd to not have a consistent naming convention. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: linux-arch@vger.kernel.org
2009-12-14locking: Convert __raw_spin* functions to arch_spin*Thomas Gleixner
Name space cleanup. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: linux-arch@vger.kernel.org
2009-12-14locking: Convert raw_spinlock to arch_spinlockThomas Gleixner
The raw_spin* namespace was taken by lockdep for the architecture specific implementations. raw_spin_* would be the ideal name space for the spinlocks which are not converted to sleeping locks in preempt-rt. Linus suggested to convert the raw_ to arch_ locks and cleanup the name space instead of using an artifical name like core_spin, atomic_spin or whatever No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: linux-arch@vger.kernel.org
2009-04-02Allow rwlocks to re-enable interruptsRobin Holt
Pass the original flags to rwlock arch-code, so that it can re-enable interrupts if implemented for that architecture. Initially, make __raw_read_lock_flags and __raw_write_lock_flags stubs which just do the same thing as non-flags variants. Signed-off-by: Petr Tesarik <ptesarik@suse.cz> Signed-off-by: Robin Holt <holt@sgi.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: <linux-arch@vger.kernel.org> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-02[ARM] move include/asm-arm to arch/arm/include/asmRussell King
Move platform independent header files to arch/arm/include/asm, leaving those in asm/arch* and asm/plat* alone. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>