From: Will Deacon <will.deacon@arm.com>
To: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
"Paul E. McKenney" <paulmck@linux.ibm.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Arnd Bergmann <arnd@arndb.de>,
Peter Zijlstra <peterz@infradead.org>,
Andrea Parri <andrea.parri@amarulasolutions.com>,
Palmer Dabbelt <palmer@sifive.com>,
Daniel Lustig <dlustig@nvidia.com>,
David Howells <dhowells@redhat.com>,
Alan Stern <stern@rowland.harvard.edu>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Maciej W. Rozycki" <macro@linux-mips.org>,
Paul Burton <paul.burton@mips.com>,
Ingo Molnar <mingo@kernel.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>, Tony Luck <tony.luck@intel.com>,
Mikulas Patocka <mpatocka@redhat.com>,
Akira Yokosawa <akiyks@gmail.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v2 12/21] ia64/mmiowb: Add unconditional mmiowb() to arch_spin_unlock()
Date: Fri, 5 Apr 2019 14:59:27 +0100 [thread overview]
Message-ID: <20190405135936.7266-13-will.deacon@arm.com> (raw)
In-Reply-To: <20190405135936.7266-1-will.deacon@arm.com>
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.
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
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 <asm/machvec.h>
+
+/**
+ * ___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 <asm-generic/mmiowb.h>
+
+#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);
}
--
2.11.0
next prev parent reply other threads:[~2019-04-05 14:01 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-05 13:59 [PATCH v2 00/21] Remove Mysterious Macro Intended to Obscure Weird Behaviours (mmiowb()) Will Deacon
2019-04-05 13:59 ` [PATCH v2 01/21] docs/memory-barriers.txt: Rewrite "KERNEL I/O BARRIER EFFECTS" section Will Deacon
2019-04-10 10:58 ` Ingo Molnar
2019-04-10 12:28 ` Will Deacon
2019-04-11 11:00 ` Ingo Molnar
2019-04-11 22:12 ` Benjamin Herrenschmidt
2019-04-11 22:34 ` Linus Torvalds
2019-04-12 2:07 ` Benjamin Herrenschmidt
2019-04-12 13:17 ` Will Deacon
2019-04-15 4:05 ` Benjamin Herrenschmidt
2019-04-16 9:13 ` Will Deacon
2019-04-05 13:59 ` [PATCH v2 02/21] asm-generic/mmiowb: Add generic implementation of mmiowb() tracking Will Deacon
2019-04-05 13:59 ` [PATCH v2 03/21] arch: Use asm-generic header for asm/mmiowb.h Will Deacon
2019-04-05 13:59 ` [PATCH v2 04/21] mmiowb: Hook up mmiowb helpers to spinlocks and generic I/O accessors Will Deacon
2019-04-05 13:59 ` [PATCH v2 05/21] ARM/io: Remove useless definition of mmiowb() Will Deacon
2019-04-05 13:59 ` [PATCH v2 06/21] arm64/io: " Will Deacon
2019-04-05 13:59 ` [PATCH v2 07/21] x86/io: " Will Deacon
2019-04-05 14:14 ` Thomas Gleixner
2019-04-05 13:59 ` [PATCH v2 08/21] nds32/io: " Will Deacon
2019-04-05 13:59 ` [PATCH v2 09/21] m68k/io: " Will Deacon
2019-04-05 13:59 ` [PATCH v2 10/21] sh/mmiowb: Add unconditional mmiowb() to arch_spin_unlock() Will Deacon
2019-04-05 13:59 ` [PATCH v2 11/21] mips/mmiowb: " Will Deacon
2019-04-05 13:59 ` Will Deacon [this message]
2019-04-05 13:59 ` [PATCH v2 13/21] powerpc/mmiowb: Hook up mmwiob() implementation to asm-generic code Will Deacon
2019-04-05 13:59 ` [PATCH v2 14/21] riscv/mmiowb: " Will Deacon
2019-04-05 13:59 ` [PATCH v2 15/21] Documentation: Kill all references to mmiowb() Will Deacon
2019-04-05 13:59 ` [PATCH v2 16/21] drivers: Remove useless trailing comments from mmiowb() invocations Will Deacon
2019-04-05 13:59 ` [PATCH v2 17/21] drivers: Remove explicit invocations of mmiowb() Will Deacon
2019-04-05 15:50 ` Linus Torvalds
2019-04-09 9:00 ` Nicholas Piggin
2019-04-09 13:46 ` Will Deacon
2019-04-10 0:25 ` Nicholas Piggin
2019-04-05 13:59 ` [PATCH v2 18/21] scsi/qla1280: Remove stale comment about mmiowb() Will Deacon
2019-04-05 13:59 ` [PATCH v2 19/21] i40iw: Redefine i40iw_mmiowb() to do nothing Will Deacon
2019-04-05 13:59 ` [PATCH v2 20/21] net/ethernet/silan/sc92031: Remove stale comment about mmiowb() Will Deacon
2019-04-05 13:59 ` [PATCH v2 21/21] arch: Remove dummy mmiowb() definitions from arch code Will Deacon
2019-04-05 15:55 ` [PATCH v2 00/21] Remove Mysterious Macro Intended to Obscure Weird Behaviours (mmiowb()) Linus Torvalds
2019-04-05 16:09 ` Will Deacon
2019-04-05 16:15 ` Linus Torvalds
2019-04-05 16:30 ` Will Deacon
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