netdev - [PATCHv4 2/2] memory barrier: adding smp_mb__after

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20090702063624.GC3429@jolsa.lab.eng.brq.redhat.com>
Date:	Thu, 2 Jul 2009 08:36:24 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	netdev@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, fbl@...hat.com, nhorman@...hat.com,
	davem@...hat.com, htejun@...il.com, jarkao2@...il.com,
	oleg@...hat.com, davidel@...ilserver.org, eric.dumazet@...il.com
Subject: [PATCHv4 2/2] memory barrier: adding 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@...hat.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 4eb8409..b3e96a4 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1280,7 +1280,7 @@ static inline int sk_has_sleeper(struct sock *sk)
 	 *
 	 * This memory barrier is paired in the sock_poll_wait.
 	 */
-	smp_mb();
+	smp_mb__after_lock();
 	return sk->sk_sleep && waitqueue_active(sk->sk_sleep);
 }
 
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html