From 54effa653246c35997f5e990e0134be5be09f9d1 Mon Sep 17 00:00:00 2001 From: Quentin Perret Date: Wed, 3 Feb 2021 14:19:30 +0000 Subject: asm-generic: export: Stub EXPORT_SYMBOL with __DISABLE_EXPORTS It is currently possible to stub EXPORT_SYMBOL() macros in C code using __DISABLE_EXPORTS, which is necessary to run in constrained environments such as the EFI stub or the decompressor. But this currently doesn't apply to exports from assembly, which can lead to somewhat confusing situations. Consolidate the __DISABLE_EXPORTS infrastructure by checking it from asm-generic/export.h as well. Signed-off-by: Quentin Perret Acked-by: Will Deacon Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210203141931.615898-2-qperret@google.com --- include/asm-generic/export.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h index 365345f9a9e3..07a36a874dca 100644 --- a/include/asm-generic/export.h +++ b/include/asm-generic/export.h @@ -33,7 +33,7 @@ */ .macro ___EXPORT_SYMBOL name,val,sec -#ifdef CONFIG_MODULES +#if defined(CONFIG_MODULES) && !defined(__DISABLE_EXPORTS) .section ___ksymtab\sec+\name,"a" .balign KSYM_ALIGN __ksymtab_\name: -- cgit v1.2.3 From 26128cb6c7e6731fe644c687af97733adfdb5ee9 Mon Sep 17 00:00:00 2001 From: Ben Gardon Date: Tue, 2 Feb 2021 10:57:12 -0800 Subject: locking/rwlocks: Add contention detection for rwlocks rwlocks do not currently have any facility to detect contention like spinlocks do. In order to allow users of rwlocks to better manage latency, add contention detection for queued rwlocks. CC: Ingo Molnar CC: Will Deacon Acked-by: Peter Zijlstra Acked-by: Davidlohr Bueso Acked-by: Waiman Long Acked-by: Paolo Bonzini Signed-off-by: Ben Gardon Message-Id: <20210202185734.1680553-7-bgardon@google.com> Signed-off-by: Paolo Bonzini --- include/asm-generic/qrwlock.h | 24 ++++++++++++++++++------ include/linux/rwlock.h | 7 +++++++ 2 files changed, 25 insertions(+), 6 deletions(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h index 84ce841ce735..0020d3b820a7 100644 --- a/include/asm-generic/qrwlock.h +++ b/include/asm-generic/qrwlock.h @@ -14,6 +14,7 @@ #include #include +#include /* * Writer states & reader shift and bias. @@ -116,15 +117,26 @@ static inline void queued_write_unlock(struct qrwlock *lock) smp_store_release(&lock->wlocked, 0); } +/** + * queued_rwlock_is_contended - check if the lock is contended + * @lock : Pointer to queue rwlock structure + * Return: 1 if lock contended, 0 otherwise + */ +static inline int queued_rwlock_is_contended(struct qrwlock *lock) +{ + return arch_spin_is_locked(&lock->wait_lock); +} + /* * Remapping rwlock architecture specific functions to the corresponding * queue rwlock functions. */ -#define arch_read_lock(l) queued_read_lock(l) -#define arch_write_lock(l) queued_write_lock(l) -#define arch_read_trylock(l) queued_read_trylock(l) -#define arch_write_trylock(l) queued_write_trylock(l) -#define arch_read_unlock(l) queued_read_unlock(l) -#define arch_write_unlock(l) queued_write_unlock(l) +#define arch_read_lock(l) queued_read_lock(l) +#define arch_write_lock(l) queued_write_lock(l) +#define arch_read_trylock(l) queued_read_trylock(l) +#define arch_write_trylock(l) queued_write_trylock(l) +#define arch_read_unlock(l) queued_read_unlock(l) +#define arch_write_unlock(l) queued_write_unlock(l) +#define arch_rwlock_is_contended(l) queued_rwlock_is_contended(l) #endif /* __ASM_GENERIC_QRWLOCK_H */ diff --git a/include/linux/rwlock.h b/include/linux/rwlock.h index 3dcd617e65ae..7ce9a51ae5c0 100644 --- a/include/linux/rwlock.h +++ b/include/linux/rwlock.h @@ -128,4 +128,11 @@ do { \ 1 : ({ local_irq_restore(flags); 0; }); \ }) +#ifdef arch_rwlock_is_contended +#define rwlock_is_contended(lock) \ + arch_rwlock_is_contended(&(lock)->raw_lock) +#else +#define rwlock_is_contended(lock) ((void)(lock), 0) +#endif /* arch_rwlock_is_contended */ + #endif /* __LINUX_RWLOCK_H */ -- cgit v1.2.3 From d8d0da4eee5c4e86ea08abde6975848376b4ac13 Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Wed, 10 Feb 2021 13:16:31 -0500 Subject: locking/arch: Move qrwlock.h include after qspinlock.h include/asm-generic/qrwlock.h was trying to get arch_spin_is_locked via asm-generic/qspinlock.h. However, this does not work because architectures might be using queued rwlocks but not queued spinlocks (csky), or because they might be defining their own queued_* macros before including asm/qspinlock.h. To fix this, ensure that asm/spinlock.h always includes qrwlock.h after defining arch_spin_is_locked (either directly for csky, or via asm/qspinlock.h for other architectures). The only inclusion elsewhere is in kernel/locking/qrwlock.c. That one is really unnecessary because the file is only compiled in SMP configurations (config QUEUED_RWLOCKS depends on SMP) and in that case linux/spinlock.h already includes asm/qrwlock.h if needed, via asm/spinlock.h. Reported-by: Guenter Roeck Signed-off-by: Waiman Long Fixes: 26128cb6c7e6 ("locking/rwlocks: Add contention detection for rwlocks") Tested-by: Guenter Roeck Reviewed-by: Ben Gardon [Add arch/sparc and kernel/locking parts per discussion with Waiman. - Paolo] Signed-off-by: Paolo Bonzini --- arch/arm64/include/asm/spinlock.h | 2 +- arch/mips/include/asm/spinlock.h | 2 +- arch/sparc/include/asm/spinlock_64.h | 2 +- arch/xtensa/include/asm/spinlock.h | 2 +- include/asm-generic/qrwlock.h | 3 ++- kernel/locking/qrwlock.c | 1 - 6 files changed, 6 insertions(+), 6 deletions(-) (limited to 'include/asm-generic') diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index 9083d6992603..0525c0b089ed 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -5,8 +5,8 @@ #ifndef __ASM_SPINLOCK_H #define __ASM_SPINLOCK_H -#include #include +#include /* See include/linux/spinlock.h */ #define smp_mb__after_spinlock() smp_mb() diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h index 8a88eb265516..6ce2117e49f6 100644 --- a/arch/mips/include/asm/spinlock.h +++ b/arch/mips/include/asm/spinlock.h @@ -10,7 +10,6 @@ #define _ASM_SPINLOCK_H #include -#include #include @@ -27,5 +26,6 @@ static inline void queued_spin_unlock(struct qspinlock *lock) } #include +#include #endif /* _ASM_SPINLOCK_H */ diff --git a/arch/sparc/include/asm/spinlock_64.h b/arch/sparc/include/asm/spinlock_64.h index 7fc82a233f49..3a9a0b0c7465 100644 --- a/arch/sparc/include/asm/spinlock_64.h +++ b/arch/sparc/include/asm/spinlock_64.h @@ -11,8 +11,8 @@ #include #include -#include #include +#include #endif /* !(__ASSEMBLY__) */ diff --git a/arch/xtensa/include/asm/spinlock.h b/arch/xtensa/include/asm/spinlock.h index 584b0de6f2ca..41c449ece2d8 100644 --- a/arch/xtensa/include/asm/spinlock.h +++ b/arch/xtensa/include/asm/spinlock.h @@ -12,8 +12,8 @@ #define _XTENSA_SPINLOCK_H #include -#include #include +#include #define smp_mb__after_spinlock() smp_mb() diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h index 0020d3b820a7..7ae0ece07b4e 100644 --- a/include/asm-generic/qrwlock.h +++ b/include/asm-generic/qrwlock.h @@ -14,7 +14,8 @@ #include #include -#include + +/* Must be included from asm/spinlock.h after defining arch_spin_is_locked. */ /* * Writer states & reader shift and bias. diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c index fe9ca92faa2a..4786dd271b45 100644 --- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -12,7 +12,6 @@ #include #include #include -#include /** * queued_read_lock_slowpath - acquire read lock of a queue rwlock -- cgit v1.2.3