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mmiowb: Hook up mmiowb helpers to spinlocks and generic I/O accessors 

Removing explicit calls to mmiowb() from driver code means that we must
now call into the generic mmiowb_spin_{lock,unlock}() functions from the
core spinlock code. In order to elide barriers following critical
sections without any I/O writes, we also hook into the asm-generic I/O
routines.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2019-02-22 12:59:59 +00:00
parent fdcd06a8ab
commit 60ca1e5a20
3 changed files with 17 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/asm-generic/io.h
View File

@ -19,6 +19,7 @@
#include <asm-generic/iomap.h>
#endif
#include <asm/mmiowb.h>
#include <asm-generic/pci_iomap.h>
#ifndef mmiowb
@ -49,7 +50,7 @@
/* serialize device access against a spin_unlock, usually handled there. */
#ifndef __io_aw
#define __io_aw() barrier()
#define __io_aw() mmiowb_set_pending()
#endif
#ifndef __io_pbw

11
include/linux/spinlock.h
View File

@ -57,6 +57,7 @@
#include <linux/stringify.h>
#include <linux/bottom_half.h>
#include <asm/barrier.h>
#include <asm/mmiowb.h>
/*
@ -178,6 +179,7 @@ static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
{
__acquire(lock);
arch_spin_lock(&lock->raw_lock);
mmiowb_spin_lock();
}
#ifndef arch_spin_lock_flags
@ -189,15 +191,22 @@ do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lo
{
__acquire(lock);
arch_spin_lock_flags(&lock->raw_lock, *flags);
mmiowb_spin_lock();
}
static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
{
return arch_spin_trylock(&(lock)->raw_lock);
int ret = arch_spin_trylock(&(lock)->raw_lock);
if (ret)
mmiowb_spin_lock();
return ret;
}
static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
{
mmiowb_spin_unlock();
arch_spin_unlock(&lock->raw_lock);
__release(lock);
}

6
kernel/locking/spinlock_debug.c
View File

@ -111,6 +111,7 @@ void do_raw_spin_lock(raw_spinlock_t *lock)
{
debug_spin_lock_before(lock);
arch_spin_lock(&lock->raw_lock);
mmiowb_spin_lock();
debug_spin_lock_after(lock);
}
@ -118,8 +119,10 @@ int do_raw_spin_trylock(raw_spinlock_t *lock)
{
int ret = arch_spin_trylock(&lock->raw_lock);
if (ret)
if (ret) {
mmiowb_spin_lock();
debug_spin_lock_after(lock);
}
#ifndef CONFIG_SMP
/*
* Must not happen on UP:
@ -131,6 +134,7 @@ int do_raw_spin_trylock(raw_spinlock_t *lock)
void do_raw_spin_unlock(raw_spinlock_t *lock)
{
mmiowb_spin_unlock();
debug_spin_unlock(lock);
arch_spin_unlock(&lock->raw_lock);
}