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glibc/pthread-cond-wait-revert.patch

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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.
Index: glibc-2.15.90/nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S
===================================================================
--- glibc-2.15.90.orig/nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S
+++ glibc-2.15.90/nptl/sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S
@@ -136,7 +136,6 @@ __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
@@ -150,9 +149,6 @@ __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
@@ -397,78 +393,6 @@ __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)
@@ -641,10 +565,6 @@ __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
Index: glibc-2.15.90/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
===================================================================
--- glibc-2.15.90.orig/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
+++ glibc-2.15.90/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
@@ -136,14 +136,11 @@ __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
@@ -331,69 +328,6 @@ __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
- LP_OP(cmp) $-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
- LP_OP(cmp) $-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
- mov dep_mutex(%rdi), %R8_LP
- 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)
@@ -546,15 +480,11 @@ __condvar_cleanup1:
.uleb128 .LcleanupSTART-.LSTARTCODE
.uleb128 .LcleanupEND-.LcleanupSTART
.uleb128 __condvar_cleanup1-.LSTARTCODE
- .uleb128 0
- .uleb128 .LcleanupSTART2-.LSTARTCODE
- .uleb128 .LcleanupEND2-.LcleanupSTART2
- .uleb128 __condvar_cleanup1-.LSTARTCODE
- .uleb128 0
+ .uleb128 0
.uleb128 .LcallUR-.LSTARTCODE
.uleb128 .LENDCODE-.LcallUR
.uleb128 0
- .uleb128 0
+ .uleb128 0
.Lcstend:
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