Messages in this thread Patch in this message | | | Date | Fri, 15 Aug 2008 12:45:09 -0400 | From | Mathieu Desnoyers <> | Subject | [PATCH] x86 : revert replace LOCK_PREFIX in futex.h |
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Depends on :
x86 alternatives : fix LOCK_PREFIX race with preemptible kernel and CPU hotplug
On Thu, 14 Aug 2008, Mathieu Desnoyers wrote: > > Changing the 0x90 (single-byte nop) currently used into a 0x3E DS segment > override prefix should fix this issue. Since the default of the atomic > instructions is to use the DS segment anyway, it should not affect the > behavior.
Ok, so I think this is an _excellent_ patch, but I'd like to also then use LOCK_PREFIX in include/asm-x86/futex.h.
See commit 9d55b9923a1b7ea8193b8875c57ec940dc2ff027.
Linus
Applies to 2.6.27-rc2 (and -rc3 unless hell broke loose in futex.h between rc2 and rc3).
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: H. Peter Anvin <hpa@zytor.com> CC: Jeremy Fitzhardinge <jeremy@goop.org> CC: Roland McGrath <roland@redhat.com> CC: Ingo Molnar <mingo@elte.hu> Cc: Steven Rostedt <rostedt@goodmis.org> CC: Steven Rostedt <srostedt@redhat.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Peter Zijlstra <peterz@infradead.org> CC: Andrew Morton <akpm@linux-foundation.org> CC: David Miller <davem@davemloft.net> CC: Ulrich Drepper <drepper@redhat.com> CC: Rusty Russell <rusty@rustcorp.com.au> CC: Gregory Haskins <ghaskins@novell.com> CC: Arnaldo Carvalho de Melo <acme@redhat.com> CC: "Luis Claudio R. Goncalves" <lclaudio@uudg.org> CC: Clark Williams <williams@redhat.com> CC: Christoph Lameter <cl@linux-foundation.org> CC: Andi Kleen <andi@firstfloor.org> CC: Harvey Harrison <harvey.harrison@gmail.com> --- include/asm-x86/futex.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
Index: linux-2.6-lttng/include/asm-x86/futex.h =================================================================== --- linux-2.6-lttng.orig/include/asm-x86/futex.h 2008-08-15 12:32:38.000000000 -0400 +++ linux-2.6-lttng/include/asm-x86/futex.h 2008-08-15 12:41:33.000000000 -0400 @@ -25,7 +25,7 @@ asm volatile("1:\tmovl %2, %0\n" \ "\tmovl\t%0, %3\n" \ "\t" insn "\n" \ - "2:\tlock; cmpxchgl %3, %2\n" \ + "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \ "\tjnz\t1b\n" \ "3:\t.section .fixup,\"ax\"\n" \ "4:\tmov\t%5, %1\n" \ @@ -64,7 +64,7 @@ static inline int futex_atomic_op_inuser __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg); break; case FUTEX_OP_ADD: - __futex_atomic_op1("lock; xaddl %0, %2", ret, oldval, + __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval, uaddr, oparg); break; case FUTEX_OP_OR: @@ -122,7 +122,7 @@ static inline int futex_atomic_cmpxchg_i if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; - asm volatile("1:\tlock; cmpxchgl %3, %1\n" + asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %3, %1\n" "2:\t.section .fixup, \"ax\"\n" "3:\tmov %2, %0\n" "\tjmp 2b\n" -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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