File pthread-cond-wait-revert.patch of Package glibc
http://sourceware.org/ml/libc-alpha/2012-01/msg00002.html
The following patch:
Has been reported as causing numerous problems in Fedora & Debian. I
don't think anyone has done any serious analysis of the issue, but the
patch has been pulled from both distributions because of the
instability it's introduced.
https://bugzilla.redhat.com/show_bug.cgi?id=769421
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=651899
commit c5a0802a682dba23f92d47f0f99775aebfbe2539
Author: Andreas Schwab <schwab@redhat.com>
Date: Mon Nov 28 13:38:19 2011 +0100
Handle EAGAIN from FUTEX_WAIT_REQUEUE_PI
2011-11-28 Andreas Schwab <schwab@redhat.com>
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S: Handle
EAGAIN from FUTEX_WAIT_REQUEUE_PI.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: Likewise.
diff --git a/nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S b/nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S
index 53970d7..54590b7 100644
--- a/nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S
+++ b/nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S
@@ -134,6 +134,7 @@ __pthread_cond_wait:
cmpl $PI_BIT, %eax
jne 18f
+90:
movl $(FUTEX_WAIT_REQUEUE_PI|FUTEX_PRIVATE_FLAG), %ecx
movl %ebp, %edx
xorl %esi, %esi
@@ -147,6 +148,9 @@ __pthread_cond_wait:
sete 16(%esp)
je 19f
+ cmpl $-EAGAIN, %eax
+ je 91f
+
/* Normal and PI futexes dont mix. Use normal futex functions only
if the kernel does not support the PI futex functions. */
cmpl $-ENOSYS, %eax
@@ -391,6 +395,78 @@ __pthread_cond_wait:
#endif
call __lll_unlock_wake
jmp 11b
+
+91:
+.LcleanupSTART2:
+ /* FUTEX_WAIT_REQUEUE_PI returned EAGAIN. We need to
+ call it again. */
+
+ /* Get internal lock. */
+ movl $1, %edx
+ xorl %eax, %eax
+ LOCK
+#if cond_lock == 0
+ cmpxchgl %edx, (%ebx)
+#else
+ cmpxchgl %edx, cond_lock(%ebx)
+#endif
+ jz 92f
+
+#if cond_lock == 0
+ movl %ebx, %edx
+#else
+ leal cond_lock(%ebx), %edx
+#endif
+#if (LLL_SHARED-LLL_PRIVATE) > 255
+ xorl %ecx, %ecx
+#endif
+ cmpl $-1, dep_mutex(%ebx)
+ setne %cl
+ subl $1, %ecx
+ andl $(LLL_SHARED-LLL_PRIVATE), %ecx
+#if LLL_PRIVATE != 0
+ addl $LLL_PRIVATE, %ecx
+#endif
+ call __lll_lock_wait
+
+92:
+ /* Increment the cond_futex value again, so it can be used as a new
+ expected value. */
+ addl $1, cond_futex(%ebx)
+ movl cond_futex(%ebx), %ebp
+
+ /* Unlock. */
+ LOCK
+#if cond_lock == 0
+ subl $1, (%ebx)
+#else
+ subl $1, cond_lock(%ebx)
+#endif
+ je 93f
+#if cond_lock == 0
+ movl %ebx, %eax
+#else
+ leal cond_lock(%ebx), %eax
+#endif
+#if (LLL_SHARED-LLL_PRIVATE) > 255
+ xorl %ecx, %ecx
+#endif
+ cmpl $-1, dep_mutex(%ebx)
+ setne %cl
+ subl $1, %ecx
+ andl $(LLL_SHARED-LLL_PRIVATE), %ecx
+#if LLL_PRIVATE != 0
+ addl $LLL_PRIVATE, %ecx
+#endif
+ call __lll_unlock_wake
+
+93:
+ /* Set the rest of SYS_futex args for FUTEX_WAIT_REQUEUE_PI. */
+ xorl %ecx, %ecx
+ movl dep_mutex(%ebx), %edi
+ jmp 90b
+.LcleanupEND2:
+
.size __pthread_cond_wait, .-__pthread_cond_wait
versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait,
GLIBC_2_3_2)
@@ -563,6 +639,10 @@ __condvar_w_cleanup:
.long .LcleanupEND-.Lsub_cond_futex
.long __condvar_w_cleanup-.LSTARTCODE
.uleb128 0
+ .long .LcleanupSTART2-.LSTARTCODE
+ .long .LcleanupEND2-.LcleanupSTART2
+ .long __condvar_w_cleanup-.LSTARTCODE
+ .uleb128 0
.long .LcallUR-.LSTARTCODE
.long .LENDCODE-.LcallUR
.long 0
diff --git a/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S b/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
index 7535baa..d837d15 100644
--- a/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
+++ b/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
@@ -23,6 +23,7 @@
#include <lowlevelcond.h>
#include <tcb-offsets.h>
#include <pthread-pi-defines.h>
+#include <pthread-errnos.h>
#include <kernel-features.h>
@@ -133,11 +134,14 @@ __pthread_cond_wait:
cmpl $PI_BIT, %eax
jne 61f
+90:
movl $(FUTEX_WAIT_REQUEUE_PI|FUTEX_PRIVATE_FLAG), %esi
movl $SYS_futex, %eax
syscall
movl $1, %r8d
+ cmpq $-EAGAIN, %rax
+ je 91f
#ifdef __ASSUME_REQUEUE_PI
jmp 62f
#else
@@ -324,6 +328,70 @@ __pthread_cond_wait:
13: movq %r10, %rax
jmp 14b
+
+91:
+.LcleanupSTART2:
+ /* FUTEX_WAIT_REQUEUE_PI returned EAGAIN. We need to
+ call it again. */
+ movq 8(%rsp), %rdi
+
+ /* Get internal lock. */
+ movl $1, %esi
+ xorl %eax, %eax
+ LOCK
+#if cond_lock == 0
+ cmpxchgl %esi, (%rdi)
+#else
+ cmpxchgl %esi, cond_lock(%rdi)
+#endif
+ jz 92f
+
+#if cond_lock != 0
+ addq $cond_lock, %rdi
+#endif
+ cmpq $-1, dep_mutex-cond_lock(%rdi)
+ movl $LLL_PRIVATE, %eax
+ movl $LLL_SHARED, %esi
+ cmovne %eax, %esi
+ callq __lll_lock_wait
+#if cond_lock != 0
+ subq $cond_lock, %rdi
+#endif
+92:
+ /* Increment the cond_futex value again, so it can be used as a new
+ expected value. */
+ incl cond_futex(%rdi)
+ movl cond_futex(%rdi), %edx
+
+ /* Release internal lock. */
+ LOCK
+#if cond_lock == 0
+ decl (%rdi)
+#else
+ decl cond_lock(%rdi)
+#endif
+ jz 93f
+
+#if cond_lock != 0
+ addq $cond_lock, %rdi
+#endif
+ cmpq $-1, dep_mutex-cond_lock(%rdi)
+ movl $LLL_PRIVATE, %eax
+ movl $LLL_SHARED, %esi
+ cmovne %eax, %esi
+ /* The call preserves %rdx. */
+ callq __lll_unlock_wake
+#if cond_lock != 0
+ subq $cond_lock, %rdi
+#endif
+93:
+ /* Set the rest of SYS_futex args for FUTEX_WAIT_REQUEUE_PI. */
+ xorq %r10, %r10
+ movq dep_mutex(%rdi), %r8
+ leaq cond_futex(%rdi), %rdi
+ jmp 90b
+.LcleanupEND2:
+
.size __pthread_cond_wait, .-__pthread_cond_wait
versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait,
GLIBC_2_3_2)
@@ -476,11 +544,15 @@ __condvar_cleanup1:
.uleb128 .LcleanupSTART-.LSTARTCODE
.uleb128 .LcleanupEND-.LcleanupSTART
.uleb128 __condvar_cleanup1-.LSTARTCODE
- .uleb128 0
+ .uleb128 0
+ .uleb128 .LcleanupSTART2-.LSTARTCODE
+ .uleb128 .LcleanupEND2-.LcleanupSTART2
+ .uleb128 __condvar_cleanup1-.LSTARTCODE
+ .uleb128 0
.uleb128 .LcallUR-.LSTARTCODE
.uleb128 .LENDCODE-.LcallUR
.uleb128 0
- .uleb128 0
+ .uleb128 0
.Lcstend:
