From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: dev@dpdk.org
Subject: [dpdk-dev] [PATCH] spinlock: fix atomic and out of order execution
Date: Sat, 21 Dec 2013 00:37:36 +0100 [thread overview]
Message-ID: <1387582656-1892-1-git-send-email-thomas.monjalon@6wind.com> (raw)
From: Damien Millescamps <damien.millescamps@6wind.com>
Add lock prefix before xchg instructions in order to be atomic
and flush speculative values to ensure effective execution order
(as an acquire barrier).
MPLOCKED is a "lock" in multicore case.
Signed-off-by: Damien Millescamps <damien.millescamps@6wind.com>
Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
---
lib/librte_eal/common/include/rte_spinlock.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/lib/librte_eal/common/include/rte_spinlock.h b/lib/librte_eal/common/include/rte_spinlock.h
index f7a245a..8edb971 100644
--- a/lib/librte_eal/common/include/rte_spinlock.h
+++ b/lib/librte_eal/common/include/rte_spinlock.h
@@ -51,6 +51,7 @@
extern "C" {
#endif
+#include <rte_atomic.h>
#include <rte_lcore.h>
#ifdef RTE_FORCE_INTRINSICS
#include <rte_common.h>
@@ -93,7 +94,7 @@ rte_spinlock_lock(rte_spinlock_t *sl)
int lock_val = 1;
asm volatile (
"1:\n"
- "xchg %[locked], %[lv]\n"
+ MPLOCKED "xchg %[locked], %[lv]\n"
"test %[lv], %[lv]\n"
"jz 3f\n"
"2:\n"
@@ -124,7 +125,7 @@ rte_spinlock_unlock (rte_spinlock_t *sl)
#ifndef RTE_FORCE_INTRINSICS
int unlock_val = 0;
asm volatile (
- "xchg %[locked], %[ulv]\n"
+ MPLOCKED "xchg %[locked], %[ulv]\n"
: [locked] "=m" (sl->locked), [ulv] "=q" (unlock_val)
: "[ulv]" (unlock_val)
: "memory");
@@ -148,7 +149,7 @@ rte_spinlock_trylock (rte_spinlock_t *sl)
int lockval = 1;
asm volatile (
- "xchg %[locked], %[lockval]"
+ MPLOCKED "xchg %[locked], %[lockval]"
: [locked] "=m" (sl->locked), [lockval] "=q" (lockval)
: "[lockval]" (lockval)
: "memory");
--
1.7.10.4
next reply other threads:[~2013-12-20 23:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-20 23:37 Thomas Monjalon [this message]
2014-01-02 16:32 ` Stephen Hemminger
2014-01-10 18:02 ` François-Frédéric Ozog
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