[linuxsh-dev] Re: Problem with pthread mutex

[kaz K. <kk...@rr...>]

Hi,

Lewis Girod <mim...@ya...> wrote:
> Mitch Davis <md...@po...> wrote:
>> Could you post the source for a tiny program which
>> demonstrates the mutex problem?
> 
> Yes..  the following program demonstrates the problem,
> although it works fine on an x86 system.  It would be
> helpful to know if other people see this problem; it
> might very well be something wrong with our
> development environment..

I've just found a few reverse tests in our spinlock implementation
in GNU libc/linuxthreads. Your test program behaves same as in x86
with applying the attached patch to glibc.  Can you please test
this patch?
The last part of the diff to pt-machine.h is irrelevant to this
problem and very experimental. So you can delete it.
Thank you for your test program and sorry for my bad response.

	kaz
--
Index: pspinlock.c
===================================================================
RCS file: /cvs/glibc/libc/linuxthreads/sysdeps/sh/pspinlock.c,v
retrieving revision 1.2
diff -u -r1.2 pspinlock.c
--- pspinlock.c	2000/12/27 17:17:16	1.2
+++ pspinlock.c	2001/04/09 02:24:11
@@ -31,7 +31,7 @@
 		  : "=r" (val)
 		  : "r" (lock)
 		  : "memory");
-  while (val != 0);
+  while (val == 0);
 
   return 0;
 }
@@ -47,7 +47,7 @@
 		: "=r" (val)
 		: "r" (lock)
 		: "memory");
-  return val ? EBUSY : 0;
+  return val ? 0 : EBUSY;
 }
 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
 
Index: pt-machine.h
===================================================================
RCS file: /cvs/glibc/libc/linuxthreads/sysdeps/sh/pt-machine.h,v
retrieving revision 1.3
diff -u -r1.3 pt-machine.h
--- pt-machine.h	2000/12/18 05:55:14	1.3
+++ pt-machine.h	2001/04/09 02:24:12
@@ -32,11 +32,11 @@
   __asm__ __volatile__(
        "tas.b	@%1\n\t"
        "movt	%0"
-       : "=z" (ret)
+       : "=r" (ret)
        : "r" (spinlock)
        : "memory", "cc");
 
-  return ret;
+  return (ret == 0);
 }
 
 
@@ -44,3 +44,13 @@
    of the stack, just something somewhere in the current frame.  */
 #define CURRENT_STACK_FRAME  stack_pointer
 register char * stack_pointer __asm__ ("r15");
+
+/* Return the thread descriptor for the current thread.  */
+struct _pthread_descr_struct;
+#define THREAD_SELF \
+  ({ struct _pthread_descr_struct *self; \
+      __asm__("stc gbr,%0" : "=r" (self)); self;})
+
+/* Initialize the thread-unique value.  */
+#define INIT_THREAD_SELF(descr, nr) \
+  ({ __asm__("ldc %0,gbr" : : "r" (descr));})