| Message ID | 20090630104106.GD9657@jolsa.lab.eng.brq.redhat.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
Jiri Olsa a écrit : > Adding smp_mb__after_lock define to be used as a smp_mb call after > a lock. > > Making it nop for x86, since {read|write|spin}_lock() on x86 are > full memory barriers. > > wbr, > jirka > > > Signed-off-by: Jiri Olsa <jolsa@redhat.com> > > --- > arch/x86/include/asm/spinlock.h | 3 +++ > include/linux/spinlock.h | 5 +++++ > include/net/sock.h | 2 +- > 3 files changed, 9 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h > index b7e5db8..39ecc5f 100644 > --- a/arch/x86/include/asm/spinlock.h > +++ b/arch/x86/include/asm/spinlock.h > @@ -302,4 +302,7 @@ static inline void __raw_write_unlock(raw_rwlock_t *rw) > #define _raw_read_relax(lock) cpu_relax() > #define _raw_write_relax(lock) cpu_relax() > > +/* The {read|write|spin}_lock() on x86 are full memory barriers. */ > +#define smp_mb__after_lock() do { } while (0) > + > #endif /* _ASM_X86_SPINLOCK_H */ > diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h > index 252b245..ae053bd 100644 > --- a/include/linux/spinlock.h > +++ b/include/linux/spinlock.h > @@ -132,6 +132,11 @@ do { \ > #endif /*__raw_spin_is_contended*/ > #endif > > +/* The lock does not imply full memory barrier. */ > +#ifndef smp_mb__after_lock > +#define smp_mb__after_lock() smp_mb() > +#endif > + > /** > * spin_unlock_wait - wait until the spinlock gets unlocked > * @lock: the spinlock in question. > diff --git a/include/net/sock.h b/include/net/sock.h > index a12df10..0d57e83 100644 > --- a/include/net/sock.h > +++ b/include/net/sock.h > @@ -1277,7 +1277,7 @@ static inline void sock_poll_wait(struct file *filp, > * > * This memory barrier is paired in the sk_has_sleeper. > */ > - smp_mb(); > + smp_mb__after_lock(); > } > } I believe you took wrong point to use this new thing :) It was meant to be used in sk_has_sleeper() only (as sk_has_sleeper() follows a read_lock()) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jun 30, 2009 at 01:14:20PM +0200, Eric Dumazet wrote: > Jiri Olsa a écrit : > > Adding smp_mb__after_lock define to be used as a smp_mb call after > > a lock. > > > > Making it nop for x86, since {read|write|spin}_lock() on x86 are > > full memory barriers. > > > > wbr, > > jirka > > > > > > Signed-off-by: Jiri Olsa <jolsa@redhat.com> > > > > --- > > arch/x86/include/asm/spinlock.h | 3 +++ > > include/linux/spinlock.h | 5 +++++ > > include/net/sock.h | 2 +- > > 3 files changed, 9 insertions(+), 1 deletions(-) > > > > diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h > > index b7e5db8..39ecc5f 100644 > > --- a/arch/x86/include/asm/spinlock.h > > +++ b/arch/x86/include/asm/spinlock.h > > @@ -302,4 +302,7 @@ static inline void __raw_write_unlock(raw_rwlock_t *rw) > > #define _raw_read_relax(lock) cpu_relax() > > #define _raw_write_relax(lock) cpu_relax() > > > > +/* The {read|write|spin}_lock() on x86 are full memory barriers. */ > > +#define smp_mb__after_lock() do { } while (0) > > + > > #endif /* _ASM_X86_SPINLOCK_H */ > > diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h > > index 252b245..ae053bd 100644 > > --- a/include/linux/spinlock.h > > +++ b/include/linux/spinlock.h > > @@ -132,6 +132,11 @@ do { \ > > #endif /*__raw_spin_is_contended*/ > > #endif > > > > +/* The lock does not imply full memory barrier. */ > > +#ifndef smp_mb__after_lock > > +#define smp_mb__after_lock() smp_mb() > > +#endif > > + > > /** > > * spin_unlock_wait - wait until the spinlock gets unlocked > > * @lock: the spinlock in question. > > diff --git a/include/net/sock.h b/include/net/sock.h > > index a12df10..0d57e83 100644 > > --- a/include/net/sock.h > > +++ b/include/net/sock.h > > @@ -1277,7 +1277,7 @@ static inline void sock_poll_wait(struct file *filp, > > * > > * This memory barrier is paired in the sk_has_sleeper. > > */ > > - smp_mb(); > > + smp_mb__after_lock(); > > } > > } > > I believe you took wrong point to use this new thing :) > > It was meant to be used in sk_has_sleeper() only (as sk_has_sleeper() > follows a read_lock()) > shoot, you're right.. I'll resend 2/2, thanks jirka -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index b7e5db8..39ecc5f 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -302,4 +302,7 @@ static inline void __raw_write_unlock(raw_rwlock_t *rw) #define _raw_read_relax(lock) cpu_relax() #define _raw_write_relax(lock) cpu_relax() +/* The {read|write|spin}_lock() on x86 are full memory barriers. */ +#define smp_mb__after_lock() do { } while (0) + #endif /* _ASM_X86_SPINLOCK_H */ diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 252b245..ae053bd 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -132,6 +132,11 @@ do { \ #endif /*__raw_spin_is_contended*/ #endif +/* The lock does not imply full memory barrier. */ +#ifndef smp_mb__after_lock +#define smp_mb__after_lock() smp_mb() +#endif + /** * spin_unlock_wait - wait until the spinlock gets unlocked * @lock: the spinlock in question. diff --git a/include/net/sock.h b/include/net/sock.h index a12df10..0d57e83 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1277,7 +1277,7 @@ static inline void sock_poll_wait(struct file *filp, * * This memory barrier is paired in the sk_has_sleeper. */ - smp_mb(); + smp_mb__after_lock(); } }
Adding smp_mb__after_lock define to be used as a smp_mb call after a lock. Making it nop for x86, since {read|write|spin}_lock() on x86 are full memory barriers. wbr, jirka Signed-off-by: Jiri Olsa <jolsa@redhat.com> --- arch/x86/include/asm/spinlock.h | 3 +++ include/linux/spinlock.h | 5 +++++ include/net/sock.h | 2 +- 3 files changed, 9 insertions(+), 1 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html