Re: [PATCH] locking: remove spin_lock_flags() etc
Peter Zijlstra writes:
> On Mon, Oct 25, 2021 at 03:06:24PM +0200, Arnd Bergmann wrote:
>> On Mon, Oct 25, 2021 at 11:57 AM Peter Zijlstra wrote:
>> > On Sat, Oct 23, 2021 at 06:04:57PM +0200, Arnd Bergmann wrote:
>> > > On Sat, Oct 23, 2021 at 3:37 AM Waiman Long wrote:
>> > > >> On 10/22/21 7:59 AM, Arnd Bergmann wrote:
>> > > > > From: Arnd Bergmann
>> > > > >
>> > > > > As this is all dead code, just remove it and the helper functions
>> > > > > built
>> > > > > around it. For arch/ia64, the inline asm could be cleaned up, but
>> > > > > it seems safer to leave it untouched.
>> > > > >
>> > > > > Signed-off-by: Arnd Bergmann
>> > > >
>> > > > Does that mean we can also remove the GENERIC_LOCKBREAK config option
>> > > > from the Kconfig files as well?
>> > >
>> > > I couldn't figure this out.
>> > >
>> > > What I see is that the only architectures setting GENERIC_LOCKBREAK are
>> > > nds32, parisc, powerpc, s390, sh and sparc64, while the only
>> > > architectures
>> > > implementing arch_spin_is_contended() are arm32, csky and ia64.
>> > >
>> > > The part I don't understand is whether the option actually does anything
>> > > useful any more after commit d89c70356acf ("locking/core: Remove
>> > > break_lock
>> > > field when CONFIG_GENERIC_LOCKBREAK=y").
>> >
>> > Urgh, what a mess.. AFAICT there's still code in
>> > kernel/locking/spinlock.c that relies on it. Specifically when
>> > GENERIC_LOCKBREAK=y we seem to create _lock*() variants that are
>> > basically TaS locks which drop preempt/irq disable while spinning.
>> >
>> > Anybody having this on and not having native TaS locks is in for a rude
>> > surprise I suppose... sparc64 being the obvious candidate there :/
>>
>> Is this a problem on s390 and powerpc, those two being the ones
>> that matter in practice?
>>
>> On s390, we pick between the cmpxchg() based directed-yield when
>> running on virtualized CPUs, and a normal qspinlock when running on a
>> dedicated CPU.
>>
>> On PowerPC, we pick at compile-time between either the qspinlock
>> (default-enabled on Book3S-64, i.e. all server chips) or a ll/sc based
>> spinlock plus vm_yield() (default on embedded and 32-bit mac).
>
> Urgh, yeah, so this crud undermines the whole point of having a fair
> lock. I'm thinking s390 and Power want to have this fixed.
Our Kconfig has:
config GENERIC_LOCKBREAK
bool
default y
depends on SMP && PREEMPTION
And we have exactly one defconfig that enables both SMP and PREEMPT,
arch/powerpc/configs/85xx/ge_imp3a_defconfig, which is some ~10 year old
PCI card embedded thing I've never heard of. High chance anyone who has
those is not running upstream kernels on them.
So I think we'd be happy for you rip GENERIC_LOCKBREAK out, it's almost
entirely unused on powerpc anyway.
cheers
Re: [PATCH] locking: remove spin_lock_flags() etc
On 10/25/21 11:44 AM, Arnd Bergmann wrote: On Mon, Oct 25, 2021 at 5:28 PM Waiman Long wrote: On 10/25/21 9:06 AM, Arnd Bergmann wrote: On s390, we pick between the cmpxchg() based directed-yield when running on virtualized CPUs, and a normal qspinlock when running on a dedicated CPU. I am not aware that s390 is using qspinlocks at all as I don't see ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see that it uses a cmpxchg based spinlock. Sorry, I should not have said "normal" here. See arch/s390/lib/spinlock.c for their custom queued spinlocks as implemented in arch_spin_lock_queued(). I don't know if that code actually does the same thing as the generic qspinlock, but it seems at least similar. Yes, you are right. Their queued lock code looks like a custom version of the pvqspinlock code. Cheers, Longman
Re: [PATCH] locking: remove spin_lock_flags() etc
On Mon, Oct 25, 2021 at 5:28 PM Waiman Long wrote: > On 10/25/21 9:06 AM, Arnd Bergmann wrote: > > > > On s390, we pick between the cmpxchg() based directed-yield when > > running on virtualized CPUs, and a normal qspinlock when running on a > > dedicated CPU. > > I am not aware that s390 is using qspinlocks at all as I don't see > ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see > that it uses a cmpxchg based spinlock. Sorry, I should not have said "normal" here. See arch/s390/lib/spinlock.c for their custom queued spinlocks as implemented in arch_spin_lock_queued(). I don't know if that code actually does the same thing as the generic qspinlock, but it seems at least similar. Arnd
Re: [PATCH] locking: remove spin_lock_flags() etc
On 10/25/21 9:06 AM, Arnd Bergmann wrote:
On Mon, Oct 25, 2021 at 11:57 AM Peter Zijlstra wrote:
On Sat, Oct 23, 2021 at 06:04:57PM +0200, Arnd Bergmann wrote:
On Sat, Oct 23, 2021 at 3:37 AM Waiman Long wrote:
On 10/22/21 7:59 AM, Arnd Bergmann wrote:
From: Arnd Bergmann
As this is all dead code, just remove it and the helper functions built
around it. For arch/ia64, the inline asm could be cleaned up, but
it seems safer to leave it untouched.
Signed-off-by: Arnd Bergmann
Does that mean we can also remove the GENERIC_LOCKBREAK config option
from the Kconfig files as well?
I couldn't figure this out.
What I see is that the only architectures setting GENERIC_LOCKBREAK are
nds32, parisc, powerpc, s390, sh and sparc64, while the only architectures
implementing arch_spin_is_contended() are arm32, csky and ia64.
The part I don't understand is whether the option actually does anything
useful any more after commit d89c70356acf ("locking/core: Remove break_lock
field when CONFIG_GENERIC_LOCKBREAK=y").
Urgh, what a mess.. AFAICT there's still code in
kernel/locking/spinlock.c that relies on it. Specifically when
GENERIC_LOCKBREAK=y we seem to create _lock*() variants that are
basically TaS locks which drop preempt/irq disable while spinning.
Anybody having this on and not having native TaS locks is in for a rude
surprise I suppose... sparc64 being the obvious candidate there :/
Is this a problem on s390 and powerpc, those two being the ones
that matter in practice?
On s390, we pick between the cmpxchg() based directed-yield when
running on virtualized CPUs, and a normal qspinlock when running on a
dedicated CPU.
I am not aware that s390 is using qspinlocks at all as I don't see
ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see
that it uses a cmpxchg based spinlock.
Cheers,
Longman
Re: [PATCH] locking: remove spin_lock_flags() etc
On Mon, Oct 25, 2021 at 03:06:24PM +0200, Arnd Bergmann wrote:
> On Mon, Oct 25, 2021 at 11:57 AM Peter Zijlstra wrote:
> > On Sat, Oct 23, 2021 at 06:04:57PM +0200, Arnd Bergmann wrote:
> > > On Sat, Oct 23, 2021 at 3:37 AM Waiman Long wrote:
> > > >> On 10/22/21 7:59 AM, Arnd Bergmann wrote:
> > > > > From: Arnd Bergmann
> > > > >
> > > > > As this is all dead code, just remove it and the helper functions
> > > > > built
> > > > > around it. For arch/ia64, the inline asm could be cleaned up, but
> > > > > it seems safer to leave it untouched.
> > > > >
> > > > > Signed-off-by: Arnd Bergmann
> > > >
> > > > Does that mean we can also remove the GENERIC_LOCKBREAK config option
> > > > from the Kconfig files as well?
> > >
> > > I couldn't figure this out.
> > >
> > > What I see is that the only architectures setting GENERIC_LOCKBREAK are
> > > nds32, parisc, powerpc, s390, sh and sparc64, while the only architectures
> > > implementing arch_spin_is_contended() are arm32, csky and ia64.
> > >
> > > The part I don't understand is whether the option actually does anything
> > > useful any more after commit d89c70356acf ("locking/core: Remove
> > > break_lock
> > > field when CONFIG_GENERIC_LOCKBREAK=y").
> >
> > Urgh, what a mess.. AFAICT there's still code in
> > kernel/locking/spinlock.c that relies on it. Specifically when
> > GENERIC_LOCKBREAK=y we seem to create _lock*() variants that are
> > basically TaS locks which drop preempt/irq disable while spinning.
> >
> > Anybody having this on and not having native TaS locks is in for a rude
> > surprise I suppose... sparc64 being the obvious candidate there :/
>
> Is this a problem on s390 and powerpc, those two being the ones
> that matter in practice?
>
> On s390, we pick between the cmpxchg() based directed-yield when
> running on virtualized CPUs, and a normal qspinlock when running on a
> dedicated CPU.
>
> On PowerPC, we pick at compile-time between either the qspinlock
> (default-enabled on Book3S-64, i.e. all server chips) or a ll/sc based
> spinlock plus vm_yield() (default on embedded and 32-bit mac).
Urgh, yeah, so this crud undermines the whole point of having a fair
lock. I'm thinking s390 and Power want to have this fixed.
Re: [PATCH] locking: remove spin_lock_flags() etc
On Mon, Oct 25, 2021 at 11:57 AM Peter Zijlstra wrote:
> On Sat, Oct 23, 2021 at 06:04:57PM +0200, Arnd Bergmann wrote:
> > On Sat, Oct 23, 2021 at 3:37 AM Waiman Long wrote:
> > >> On 10/22/21 7:59 AM, Arnd Bergmann wrote:
> > > > From: Arnd Bergmann
> > > >
> > > > As this is all dead code, just remove it and the helper functions built
> > > > around it. For arch/ia64, the inline asm could be cleaned up, but
> > > > it seems safer to leave it untouched.
> > > >
> > > > Signed-off-by: Arnd Bergmann
> > >
> > > Does that mean we can also remove the GENERIC_LOCKBREAK config option
> > > from the Kconfig files as well?
> >
> > I couldn't figure this out.
> >
> > What I see is that the only architectures setting GENERIC_LOCKBREAK are
> > nds32, parisc, powerpc, s390, sh and sparc64, while the only architectures
> > implementing arch_spin_is_contended() are arm32, csky and ia64.
> >
> > The part I don't understand is whether the option actually does anything
> > useful any more after commit d89c70356acf ("locking/core: Remove break_lock
> > field when CONFIG_GENERIC_LOCKBREAK=y").
>
> Urgh, what a mess.. AFAICT there's still code in
> kernel/locking/spinlock.c that relies on it. Specifically when
> GENERIC_LOCKBREAK=y we seem to create _lock*() variants that are
> basically TaS locks which drop preempt/irq disable while spinning.
>
> Anybody having this on and not having native TaS locks is in for a rude
> surprise I suppose... sparc64 being the obvious candidate there :/
Is this a problem on s390 and powerpc, those two being the ones
that matter in practice?
On s390, we pick between the cmpxchg() based directed-yield when
running on virtualized CPUs, and a normal qspinlock when running on a
dedicated CPU.
On PowerPC, we pick at compile-time between either the qspinlock
(default-enabled on Book3S-64, i.e. all server chips) or a ll/sc based
spinlock plus vm_yield() (default on embedded and 32-bit mac).
Arnd
Re: [PATCH] locking: remove spin_lock_flags() etc
On Mon, Oct 25, 2021 at 11:57:28AM +0200, Peter Zijlstra wrote:
> On Sat, Oct 23, 2021 at 06:04:57PM +0200, Arnd Bergmann wrote:
> > On Sat, Oct 23, 2021 at 3:37 AM Waiman Long wrote:
> > >> On 10/22/21 7:59 AM, Arnd Bergmann wrote:
> > > > From: Arnd Bergmann
> > > >
> > > > As this is all dead code, just remove it and the helper functions built
> > > > around it. For arch/ia64, the inline asm could be cleaned up, but
> > > > it seems safer to leave it untouched.
> > > >
> > > > Signed-off-by: Arnd Bergmann
> > >
> > > Does that mean we can also remove the GENERIC_LOCKBREAK config option
> > > from the Kconfig files as well?
> >
> > I couldn't figure this out.
> >
> > What I see is that the only architectures setting GENERIC_LOCKBREAK are
> > nds32, parisc, powerpc, s390, sh and sparc64, while the only architectures
> > implementing arch_spin_is_contended() are arm32, csky and ia64.
> >
> > The part I don't understand is whether the option actually does anything
> > useful any more after commit d89c70356acf ("locking/core: Remove break_lock
> > field when CONFIG_GENERIC_LOCKBREAK=y").
>
> Urgh, what a mess.. AFAICT there's still code in
> kernel/locking/spinlock.c that relies on it. Specifically when
> GENERIC_LOCKBREAK=y we seem to create _lock*() variants that are
> basically TaS locks which drop preempt/irq disable while spinning.
>
> Anybody having this on and not having native TaS locks is in for a rude
> surprise I suppose... sparc64 being the obvious candidate there :/
Something like the *totally*untested* patch below would rip it all out.
---
arch/ia64/Kconfig| 3 --
arch/nds32/Kconfig | 4 --
arch/parisc/Kconfig | 5 ---
arch/powerpc/Kconfig | 5 ---
arch/s390/Kconfig| 3 --
arch/sh/Kconfig | 4 --
arch/sparc/Kconfig | 6 ---
include/linux/rwlock_api_smp.h | 4 +-
include/linux/spinlock_api_smp.h | 4 +-
kernel/Kconfig.locks | 26 ++--
kernel/locking/spinlock.c| 90
11 files changed, 17 insertions(+), 137 deletions(-)
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 1e33666fa679..5ec3abba3c81 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -81,9 +81,6 @@ config MMU
config STACKTRACE_SUPPORT
def_bool y
-config GENERIC_LOCKBREAK
- def_bool n
-
config GENERIC_CALIBRATE_DELAY
bool
default y
diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig
index aea26e739543..699008dbd6c2 100644
--- a/arch/nds32/Kconfig
+++ b/arch/nds32/Kconfig
@@ -59,10 +59,6 @@ config GENERIC_CSUM
config GENERIC_HWEIGHT
def_bool y
-config GENERIC_LOCKBREAK
- def_bool y
- depends on PREEMPTION
-
config STACKTRACE_SUPPORT
def_bool y
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 27a8b49af11f..afe70bcdde2c 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -86,11 +86,6 @@ config ARCH_DEFCONFIG
default "arch/parisc/configs/generic-32bit_defconfig" if !64BIT
default "arch/parisc/configs/generic-64bit_defconfig" if 64BIT
-config GENERIC_LOCKBREAK
- bool
- default y
- depends on SMP && PREEMPTION
-
config ARCH_HAS_ILOG2_U32
bool
default n
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index ba5b66189358..e782c9ea3f81 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -98,11 +98,6 @@ config LOCKDEP_SUPPORT
bool
default y
-config GENERIC_LOCKBREAK
- bool
- default y
- depends on SMP && PREEMPTION
-
config GENERIC_HWEIGHT
bool
default y
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b86de61b8caa..e4ff05f5393b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -26,9 +26,6 @@ config GENERIC_BUG
config GENERIC_BUG_RELATIVE_POINTERS
def_bool y
-config GENERIC_LOCKBREAK
- def_bool y if PREEMPTION
-
config PGSTE
def_bool y if KVM
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 6904f4bdbf00..26f1cf2c69a3 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -86,10 +86,6 @@ config GENERIC_HWEIGHT
config GENERIC_CALIBRATE_DELAY
bool
-config GENERIC_LOCKBREAK
- def_bool y
- depends on SMP && PREEMPTION
-
config ARCH_SUSPEND_POSSIBLE
def_bool n
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index b120ed947f50..e77e7254eaa0 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -246,12 +246,6 @@ config US3_MC
If in doubt, say Y, as this information can be very useful.
-# Global things across all Sun machines.
-config GENERIC_LOCKBREAK
- bool
- default y
- depends on SPARC64 && SMP && PREEMPTION
-
config NUMA
bool "NUMA support"
depends on SPARC64 && SMP
diff --git a/include/linux/rwlock_api_smp.h b/include/linux/rwlock_api_smp.h
index abfb53ab11be..a281d81ef8ee 100644
---
Re: [PATCH] locking: remove spin_lock_flags() etc
On Sat, Oct 23, 2021 at 06:04:57PM +0200, Arnd Bergmann wrote:
> On Sat, Oct 23, 2021 at 3:37 AM Waiman Long wrote:
> >> On 10/22/21 7:59 AM, Arnd Bergmann wrote:
> > > From: Arnd Bergmann
> > >
> > > As this is all dead code, just remove it and the helper functions built
> > > around it. For arch/ia64, the inline asm could be cleaned up, but
> > > it seems safer to leave it untouched.
> > >
> > > Signed-off-by: Arnd Bergmann
> >
> > Does that mean we can also remove the GENERIC_LOCKBREAK config option
> > from the Kconfig files as well?
>
> I couldn't figure this out.
>
> What I see is that the only architectures setting GENERIC_LOCKBREAK are
> nds32, parisc, powerpc, s390, sh and sparc64, while the only architectures
> implementing arch_spin_is_contended() are arm32, csky and ia64.
>
> The part I don't understand is whether the option actually does anything
> useful any more after commit d89c70356acf ("locking/core: Remove break_lock
> field when CONFIG_GENERIC_LOCKBREAK=y").
Urgh, what a mess.. AFAICT there's still code in
kernel/locking/spinlock.c that relies on it. Specifically when
GENERIC_LOCKBREAK=y we seem to create _lock*() variants that are
basically TaS locks which drop preempt/irq disable while spinning.
Anybody having this on and not having native TaS locks is in for a rude
surprise I suppose... sparc64 being the obvious candidate there :/
Re: [PATCH] locking: remove spin_lock_flags() etc
On Sat, Oct 23, 2021 at 3:37 AM Waiman Long wrote:
>> On 10/22/21 7:59 AM, Arnd Bergmann wrote:
> > From: Arnd Bergmann
> >
> > As this is all dead code, just remove it and the helper functions built
> > around it. For arch/ia64, the inline asm could be cleaned up, but
> > it seems safer to leave it untouched.
> >
> > Signed-off-by: Arnd Bergmann
>
> Does that mean we can also remove the GENERIC_LOCKBREAK config option
> from the Kconfig files as well?
I couldn't figure this out.
What I see is that the only architectures setting GENERIC_LOCKBREAK are
nds32, parisc, powerpc, s390, sh and sparc64, while the only architectures
implementing arch_spin_is_contended() are arm32, csky and ia64.
The part I don't understand is whether the option actually does anything
useful any more after commit d89c70356acf ("locking/core: Remove break_lock
field when CONFIG_GENERIC_LOCKBREAK=y").
Arnd
Re: [PATCH] locking: remove spin_lock_flags() etc
On 10/22/21 7:59 AM, Arnd Bergmann wrote:
From: Arnd Bergmann
parisc, ia64 and powerpc32 are the only remaining architectures that
provide custom arch_{spin,read,write}_lock_flags() functions, which are
meant to re-enable interrupts while waiting for a spinlock.
However, none of these can actually run into this codepath, because
it is only called on architectures without CONFIG_GENERIC_LOCKBREAK,
or when CONFIG_DEBUG_LOCK_ALLOC is set without CONFIG_LOCKDEP, and none
of those combinations are possible on the three architectures.
Going back in the git history, it appears that arch/mn10300 may have
been able to run into this code path, but there is a good chance that
it never worked. On the architectures that still exist, it was
already impossible to hit back in 2008 after the introduction of
CONFIG_GENERIC_LOCKBREAK, and possibly earlier.
As this is all dead code, just remove it and the helper functions built
around it. For arch/ia64, the inline asm could be cleaned up, but
it seems safer to leave it untouched.
Signed-off-by: Arnd Bergmann
Does that mean we can also remove the GENERIC_LOCKBREAK config option
from the Kconfig files as well?
Cheers,
Longman
Re: [PATCH] locking: remove spin_lock_flags() etc
On 10/22/21 13:59, Arnd Bergmann wrote:
> From: Arnd Bergmann
>
> parisc, ia64 and powerpc32 are the only remaining architectures that
> provide custom arch_{spin,read,write}_lock_flags() functions, which are
> meant to re-enable interrupts while waiting for a spinlock.
>
> However, none of these can actually run into this codepath, because
> it is only called on architectures without CONFIG_GENERIC_LOCKBREAK,
> or when CONFIG_DEBUG_LOCK_ALLOC is set without CONFIG_LOCKDEP, and none
> of those combinations are possible on the three architectures.
>
> Going back in the git history, it appears that arch/mn10300 may have
> been able to run into this code path, but there is a good chance that
> it never worked. On the architectures that still exist, it was
> already impossible to hit back in 2008 after the introduction of
> CONFIG_GENERIC_LOCKBREAK, and possibly earlier.
>
> As this is all dead code, just remove it and the helper functions built
> around it. For arch/ia64, the inline asm could be cleaned up, but
> it seems safer to leave it untouched.
>
> Signed-off-by: Arnd Bergmann
Acked-by: Helge Deller # parisc
Helge
> ---
> arch/ia64/include/asm/spinlock.h | 23 ++
> arch/openrisc/include/asm/spinlock.h | 3 ---
> arch/parisc/include/asm/spinlock.h | 15 --
> arch/powerpc/include/asm/simple_spinlock.h | 21
> arch/s390/include/asm/spinlock.h | 8
> include/linux/lockdep.h| 17
> include/linux/rwlock.h | 15 --
> include/linux/rwlock_api_smp.h | 6 ++
> include/linux/spinlock.h | 13
> include/linux/spinlock_api_smp.h | 9 -
> include/linux/spinlock_up.h| 1 -
> kernel/locking/spinlock.c | 3 +--
> 12 files changed, 9 insertions(+), 125 deletions(-)
>
> diff --git a/arch/ia64/include/asm/spinlock.h
> b/arch/ia64/include/asm/spinlock.h
> index 864775970c50..0e5c1ad3239c 100644
> --- a/arch/ia64/include/asm/spinlock.h
> +++ b/arch/ia64/include/asm/spinlock.h
> @@ -124,18 +124,13 @@ static __always_inline void
> arch_spin_unlock(arch_spinlock_t *lock)
> __ticket_spin_unlock(lock);
> }
>
> -static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock,
> - unsigned long flags)
> -{
> - arch_spin_lock(lock);
> -}
> -#define arch_spin_lock_flags arch_spin_lock_flags
> -
> #ifdef ASM_SUPPORTED
>
> static __always_inline void
> -arch_read_lock_flags(arch_rwlock_t *lock, unsigned long flags)
> +arch_read_lock(arch_rwlock_t *lock)
> {
> + unsigned long flags = 0;
> +
> __asm__ __volatile__ (
> "tbit.nz p6, p0 = %1,%2\n"
> "br.few 3f\n"
> @@ -157,13 +152,8 @@ arch_read_lock_flags(arch_rwlock_t *lock, unsigned long
> flags)
> : "p6", "p7", "r2", "memory");
> }
>
> -#define arch_read_lock_flags arch_read_lock_flags
> -#define arch_read_lock(lock) arch_read_lock_flags(lock, 0)
> -
> #else /* !ASM_SUPPORTED */
>
> -#define arch_read_lock_flags(rw, flags) arch_read_lock(rw)
> -
> #define arch_read_lock(rw)
> \
> do {
> \
> arch_rwlock_t *__read_lock_ptr = (rw);
> \
> @@ -186,8 +176,10 @@ do {
> \
> #ifdef ASM_SUPPORTED
>
> static __always_inline void
> -arch_write_lock_flags(arch_rwlock_t *lock, unsigned long flags)
> +arch_write_lock(arch_rwlock_t *lock)
> {
> + unsigned long flags = 0;
> +
> __asm__ __volatile__ (
> "tbit.nz p6, p0 = %1, %2\n"
> "mov ar.ccv = r0\n"
> @@ -210,9 +202,6 @@ arch_write_lock_flags(arch_rwlock_t *lock, unsigned long
> flags)
> : "ar.ccv", "p6", "p7", "r2", "r29", "memory");
> }
>
> -#define arch_write_lock_flags arch_write_lock_flags
> -#define arch_write_lock(rw) arch_write_lock_flags(rw, 0)
> -
> #define arch_write_trylock(rw)
> \
> ({
> \
> register long result;
> \
> diff --git a/arch/openrisc/include/asm/spinlock.h
> b/arch/openrisc/include/asm/spinlock.h
> index a8940bdfcb7e..264944a71535 100644
> --- a/arch/openrisc/include/asm/spinlock.h
> +++ b/arch/openrisc/include/asm/spinlock.h
> @@ -19,9 +19,6 @@
>
> #include
>
> -#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
> -#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
> -
> #define arch_spin_relax(lock)cpu_relax()
> #define arch_read_relax(lock)cpu_relax()
> #define arch_write_relax(lock)
[PATCH] locking: remove spin_lock_flags() etc
From: Arnd Bergmann
parisc, ia64 and powerpc32 are the only remaining architectures that
provide custom arch_{spin,read,write}_lock_flags() functions, which are
meant to re-enable interrupts while waiting for a spinlock.
However, none of these can actually run into this codepath, because
it is only called on architectures without CONFIG_GENERIC_LOCKBREAK,
or when CONFIG_DEBUG_LOCK_ALLOC is set without CONFIG_LOCKDEP, and none
of those combinations are possible on the three architectures.
Going back in the git history, it appears that arch/mn10300 may have
been able to run into this code path, but there is a good chance that
it never worked. On the architectures that still exist, it was
already impossible to hit back in 2008 after the introduction of
CONFIG_GENERIC_LOCKBREAK, and possibly earlier.
As this is all dead code, just remove it and the helper functions built
around it. For arch/ia64, the inline asm could be cleaned up, but
it seems safer to leave it untouched.
Signed-off-by: Arnd Bergmann
---
arch/ia64/include/asm/spinlock.h | 23 ++
arch/openrisc/include/asm/spinlock.h | 3 ---
arch/parisc/include/asm/spinlock.h | 15 --
arch/powerpc/include/asm/simple_spinlock.h | 21
arch/s390/include/asm/spinlock.h | 8
include/linux/lockdep.h| 17
include/linux/rwlock.h | 15 --
include/linux/rwlock_api_smp.h | 6 ++
include/linux/spinlock.h | 13
include/linux/spinlock_api_smp.h | 9 -
include/linux/spinlock_up.h| 1 -
kernel/locking/spinlock.c | 3 +--
12 files changed, 9 insertions(+), 125 deletions(-)
diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h
index 864775970c50..0e5c1ad3239c 100644
--- a/arch/ia64/include/asm/spinlock.h
+++ b/arch/ia64/include/asm/spinlock.h
@@ -124,18 +124,13 @@ static __always_inline void
arch_spin_unlock(arch_spinlock_t *lock)
__ticket_spin_unlock(lock);
}
-static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock,
- unsigned long flags)
-{
- arch_spin_lock(lock);
-}
-#define arch_spin_lock_flags arch_spin_lock_flags
-
#ifdef ASM_SUPPORTED
static __always_inline void
-arch_read_lock_flags(arch_rwlock_t *lock, unsigned long flags)
+arch_read_lock(arch_rwlock_t *lock)
{
+ unsigned long flags = 0;
+
__asm__ __volatile__ (
"tbit.nz p6, p0 = %1,%2\n"
"br.few 3f\n"
@@ -157,13 +152,8 @@ arch_read_lock_flags(arch_rwlock_t *lock, unsigned long
flags)
: "p6", "p7", "r2", "memory");
}
-#define arch_read_lock_flags arch_read_lock_flags
-#define arch_read_lock(lock) arch_read_lock_flags(lock, 0)
-
#else /* !ASM_SUPPORTED */
-#define arch_read_lock_flags(rw, flags) arch_read_lock(rw)
-
#define arch_read_lock(rw)
\
do {
\
arch_rwlock_t *__read_lock_ptr = (rw);
\
@@ -186,8 +176,10 @@ do {
\
#ifdef ASM_SUPPORTED
static __always_inline void
-arch_write_lock_flags(arch_rwlock_t *lock, unsigned long flags)
+arch_write_lock(arch_rwlock_t *lock)
{
+ unsigned long flags = 0;
+
__asm__ __volatile__ (
"tbit.nz p6, p0 = %1, %2\n"
"mov ar.ccv = r0\n"
@@ -210,9 +202,6 @@ arch_write_lock_flags(arch_rwlock_t *lock, unsigned long
flags)
: "ar.ccv", "p6", "p7", "r2", "r29", "memory");
}
-#define arch_write_lock_flags arch_write_lock_flags
-#define arch_write_lock(rw) arch_write_lock_flags(rw, 0)
-
#define arch_write_trylock(rw)
\
({
\
register long result;
\
diff --git a/arch/openrisc/include/asm/spinlock.h
b/arch/openrisc/include/asm/spinlock.h
index a8940bdfcb7e..264944a71535 100644
--- a/arch/openrisc/include/asm/spinlock.h
+++ b/arch/openrisc/include/asm/spinlock.h
@@ -19,9 +19,6 @@
#include
-#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
-#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
-
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
diff --git a/arch/parisc/include/asm/spinlock.h
b/arch/parisc/include/asm/spinlock.h
index fa5ee8a45dbd..a6e5d66a7656 100644
--- a/arch/parisc/include/asm/spinlock.h
+++ b/arch/parisc/include/asm/spinlock.h
@@ -23,21 +23,6 @@ static inline void arch_spin_lock(arch_spinlock_t *x)
