Commit c476d8d1 authored by heikki@donna.mysql.fi's avatar heikki@donna.mysql.fi
Browse files

sync0sync.ic Use XCHG also to reset the mutex lock word: it makes a... 

sync0sync.ic	Use XCHG also to reset the mutex lock word: it makes a serialization point to code on Intel and gives more safety
parent 8ad79ab0

BitKeeper/etc/logging_ok

+1 −0
Original line number Diff line number Diff line 
jani@janikt.pp.saunalahti.fi

monty@hundin.mysql.fi

mwagner@evoq.mwagner.org

heikki@donna.mysql.fi

innobase/include/sync0sync.ic

+19 −5
Original line number Diff line number Diff line
@@ -94,10 +94,12 @@ mutex_test_and_set( 


	/* In assembly we use the so-called AT & T syntax where

	the order of operands is inverted compared to the ordinary Intel

	syntax. The 'l' after the mnemonics denotes a 32-bit operation. */

	syntax. The 'l' after the mnemonics denotes a 32-bit operation.

	The line after the code tells which values come out of the asm

	code, and the second line tells the input to the asm code. */



	asm volatile("movl $1, %%eax; xchgl (%%ecx), %%eax" :

	              "=eax" (res):

	              "=eax" (res), "=m" (*lw) :

	              "ecx" (lw));

	return(res);

#else
@@ -132,12 +134,24 @@ mutex_reset_lock_word( 
	__asm   MOV     EDX, 0

        __asm   MOV     ECX, lw

        __asm   XCHG    EDX, DWORD PTR [ECX]                    

#elif defined(__GNUC__) && defined(UNIV_INTEL_X86)

	ulint*	lw;



	lw = &(mutex->lock_word);



	/* In assembly we use the so-called AT & T syntax where

	the order of operands is inverted compared to the ordinary Intel

	syntax. The 'l' after the mnemonics denotes a 32-bit operation. */



	asm volatile("movl $0, %%eax; xchgl (%%ecx), %%eax" :

	              "=m" (*lw) :

	              "ecx" (lw) :

		      "eax");	/* gcc does not seem to understand

				that our asm code resets eax: tell it

				explicitly that after the third ':' */

#else

	mutex->lock_word = 0;

#if !(defined(__GNUC__) && defined(UNIV_INTEL_X86))

	os_fast_mutex_unlock(&(mutex->os_fast_mutex));

#endif

#endif

}



/**********************************************************************