From 49ca6462fc9e0f5a67cd96eeddd844efc3fb33b9 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 22 Feb 2019 13:37:21 +0000 Subject: [PATCH] ia64/mmiowb: Add unconditional mmiowb() to arch_spin_unlock() The mmiowb() macro is horribly difficult to use and drivers will continue to work most of the time if they omit a call when it is required. Rather than rely on driver authors getting this right, push mmiowb() into arch_spin_unlock() for ia64. If this is deemed to be a performance issue, a subsequent optimisation could make use of ARCH_HAS_MMIOWB to elide the barrier in cases where no I/O writes were performed inside the critical section. Acked-by: Linus Torvalds Signed-off-by: Will Deacon --- arch/ia64/include/asm/Kbuild | 1 - arch/ia64/include/asm/io.h | 17 ----------------- arch/ia64/include/asm/mmiowb.h | 25 +++++++++++++++++++++++++ arch/ia64/include/asm/spinlock.h | 2 ++ 4 files changed, 27 insertions(+), 18 deletions(-) create mode 100644 arch/ia64/include/asm/mmiowb.h diff --git a/arch/ia64/include/asm/Kbuild b/arch/ia64/include/asm/Kbuild index cabfe0280c33..11f191689c9e 100644 --- a/arch/ia64/include/asm/Kbuild +++ b/arch/ia64/include/asm/Kbuild @@ -5,7 +5,6 @@ generic-y += irq_work.h generic-y += kvm_para.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h -generic-y += mmiowb.h generic-y += preempt.h generic-y += trace_clock.h generic-y += vtime.h diff --git a/arch/ia64/include/asm/io.h b/arch/ia64/include/asm/io.h index 1e6fef69bb01..a511d62d447a 100644 --- a/arch/ia64/include/asm/io.h +++ b/arch/ia64/include/asm/io.h @@ -113,20 +113,6 @@ extern int valid_mmap_phys_addr_range (unsigned long pfn, size_t count); */ #define __ia64_mf_a() ia64_mfa() -/** - * ___ia64_mmiowb - I/O write barrier - * - * Ensure ordering of I/O space writes. This will make sure that writes - * following the barrier will arrive after all previous writes. For most - * ia64 platforms, this is a simple 'mf.a' instruction. - * - * See Documentation/driver-api/device-io.rst for more information. - */ -static inline void ___ia64_mmiowb(void) -{ - ia64_mfa(); -} - static inline void* __ia64_mk_io_addr (unsigned long port) { @@ -161,7 +147,6 @@ __ia64_mk_io_addr (unsigned long port) #define __ia64_writew ___ia64_writew #define __ia64_writel ___ia64_writel #define __ia64_writeq ___ia64_writeq -#define __ia64_mmiowb ___ia64_mmiowb /* * For the in/out routines, we need to do "mf.a" _after_ doing the I/O access to ensure @@ -296,7 +281,6 @@ __outsl (unsigned long port, const void *src, unsigned long count) #define __outb platform_outb #define __outw platform_outw #define __outl platform_outl -#define __mmiowb platform_mmiowb #define inb(p) __inb(p) #define inw(p) __inw(p) @@ -310,7 +294,6 @@ __outsl (unsigned long port, const void *src, unsigned long count) #define outsb(p,s,c) __outsb(p,s,c) #define outsw(p,s,c) __outsw(p,s,c) #define outsl(p,s,c) __outsl(p,s,c) -#define mmiowb() __mmiowb() /* * The address passed to these functions are ioremap()ped already. diff --git a/arch/ia64/include/asm/mmiowb.h b/arch/ia64/include/asm/mmiowb.h new file mode 100644 index 000000000000..297b85ac84a0 --- /dev/null +++ b/arch/ia64/include/asm/mmiowb.h @@ -0,0 +1,25 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _ASM_IA64_MMIOWB_H +#define _ASM_IA64_MMIOWB_H + +#include + +/** + * ___ia64_mmiowb - I/O write barrier + * + * Ensure ordering of I/O space writes. This will make sure that writes + * following the barrier will arrive after all previous writes. For most + * ia64 platforms, this is a simple 'mf.a' instruction. + */ +static inline void ___ia64_mmiowb(void) +{ + ia64_mfa(); +} + +#define __ia64_mmiowb ___ia64_mmiowb +#define mmiowb() platform_mmiowb() + +#include + +#endif /* _ASM_IA64_MMIOWB_H */ diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h index afd0b3121b4c..5f620e66384e 100644 --- a/arch/ia64/include/asm/spinlock.h +++ b/arch/ia64/include/asm/spinlock.h @@ -73,6 +73,8 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) { unsigned short *p = (unsigned short *)&lock->lock + 1, tmp; + /* This could be optimised with ARCH_HAS_MMIOWB */ + mmiowb(); asm volatile ("ld2.bias %0=[%1]" : "=r"(tmp) : "r"(p)); WRITE_ONCE(*p, (tmp + 2) & ~1); }