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 11/21] mips/mmiowb: Add unconditional mmiowb() to arch_spin_unlock()
Date: Fri, 5 Apr 2019 14:59:26 +0100 [thread overview]
Message-ID: <20190405135936.7266-12-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 mips. 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: Paul Burton <paul.burton@mips.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/mips/include/asm/Kbuild | 1 -
arch/mips/include/asm/io.h | 3 ---
arch/mips/include/asm/mmiowb.h | 11 +++++++++++
arch/mips/include/asm/spinlock.h | 15 +++++++++++++++
4 files changed, 26 insertions(+), 4 deletions(-)
create mode 100644 arch/mips/include/asm/mmiowb.h
diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index bf39c2253ec8..87b86cdf126a 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -12,7 +12,6 @@ generic-y += irq_work.h
generic-y += local64.h
generic-y += mcs_spinlock.h
generic-y += mm-arch-hooks.h
-generic-y += mmiowb.h
generic-y += msi.h
generic-y += parport.h
generic-y += percpu.h
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 845fbbc7a2e3..29997e42480e 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -102,9 +102,6 @@ static inline void set_io_port_base(unsigned long base)
#define iobarrier_w() wmb()
#define iobarrier_sync() iob()
-/* Some callers use this older API instead. */
-#define mmiowb() iobarrier_w()
-
/*
* virt_to_phys - map virtual addresses to physical
* @address: address to remap
diff --git a/arch/mips/include/asm/mmiowb.h b/arch/mips/include/asm/mmiowb.h
new file mode 100644
index 000000000000..a40824e3ef8e
--- /dev/null
+++ b/arch/mips/include/asm/mmiowb.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_MMIOWB_H
+#define _ASM_MMIOWB_H
+
+#include <asm/io.h>
+
+#define mmiowb() iobarrier_w()
+
+#include <asm-generic/mmiowb.h>
+
+#endif /* _ASM_MMIOWB_H */
diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index ee81297d9117..8a88eb265516 100644
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -11,6 +11,21 @@
#include <asm/processor.h>
#include <asm/qrwlock.h>
+
+#include <asm-generic/qspinlock_types.h>
+
+#define queued_spin_unlock queued_spin_unlock
+/**
+ * queued_spin_unlock - release a queued spinlock
+ * @lock : Pointer to queued spinlock structure
+ */
+static inline void queued_spin_unlock(struct qspinlock *lock)
+{
+ /* This could be optimised with ARCH_HAS_MMIOWB */
+ mmiowb();
+ smp_store_release(&lock->locked, 0);
+}
+
#include <asm/qspinlock.h>
#endif /* _ASM_SPINLOCK_H */
--
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 ` Will Deacon [this message]
2019-04-05 13:59 ` [PATCH v2 12/21] ia64/mmiowb: " Will Deacon
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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