diff options
Diffstat (limited to 'db2/mutex')
| -rw-r--r-- | db2/mutex/68020.gcc | 19 | ||||
| -rw-r--r-- | db2/mutex/README | 105 | ||||
| -rw-r--r-- | db2/mutex/alpha.dec | 25 | ||||
| -rw-r--r-- | db2/mutex/alpha.gcc | 52 | ||||
| -rw-r--r-- | db2/mutex/mutex.c | 280 | ||||
| -rw-r--r-- | db2/mutex/parisc.gcc | 40 | ||||
| -rw-r--r-- | db2/mutex/parisc.hp | 29 | ||||
| -rw-r--r-- | db2/mutex/sparc.gcc | 33 | ||||
| -rw-r--r-- | db2/mutex/uts4.cc.s | 21 | ||||
| -rw-r--r-- | db2/mutex/x86.gcc | 17 |
10 files changed, 621 insertions, 0 deletions
diff --git a/db2/mutex/68020.gcc b/db2/mutex/68020.gcc new file mode 100644 index 0000000000..9d8be641d8 --- /dev/null +++ b/db2/mutex/68020.gcc @@ -0,0 +1,19 @@ +/* + * @(#)68020.gcc 10.1 (Sleepycat) 4/12/97 + * + * For gcc/68K, 0 is clear, 1 is set. + */ +#define TSL_SET(tsl) ({ \ + register tsl_t *__l = (tsl); \ + int __r; \ + asm volatile("tas %1; \n \ + seq %0" \ + : "=dm" (__r), "=m" (*__l) \ + : "1" (*__l) \ + ); \ + __r & 1; \ +}) + +#define TSL_UNSET(tsl) (*(tsl) = 0) +#define TSL_INIT(tsl) TSL_UNSET(tsl) + diff --git a/db2/mutex/README b/db2/mutex/README new file mode 100644 index 0000000000..30d6b6a7d1 --- /dev/null +++ b/db2/mutex/README @@ -0,0 +1,105 @@ +# @(#)README 10.1 (Sleepycat) 4/12/97 + +Resource locking routines: lock based on a db_mutex_t. All this gunk +(including trying to make assembly code portable), is necessary because +System V semaphores require system calls for uncontested locks and we +don't want to make two system calls per resource lock. + +First, this is how it works. The db_mutex_t structure contains a resource +test-and-set lock (tsl), a file offset, a pid for debugging and statistics +information. + +If HAVE_SPINLOCKS is defined (i.e. we know how to do test-and-sets for +this compiler/architecture combination), we try and lock the resource tsl +TSL_DEFAULT_SPINS times. If we can't acquire the lock that way, we use +a system call to sleep for 10ms, 20ms, 40ms, etc. (The time is bounded +at 1 second, just in case.) Using the timer backoff means that there are +two assumptions: that locks are held for brief periods (never over system +calls or I/O) and that locks are not hotly contested. + +If HAVE_SPINLOCKS is not defined, i.e. we can't do test-and-sets, we use +a file descriptor to do byte locking on a file at a specified offset. In +this case, ALL of the locking is done in the kernel. Because file +descriptors are allocated per process, we have to provide the file +descriptor as part of the lock/unlock call. We still have to do timer +backoff because we need to be able to block ourselves, i.e. the lock +manager causes processes to wait by having the process acquire a mutex +and then attempting to re-acquire the mutex. There's no way to use kernel +locking to block yourself, i.e. if you hold a lock and attempt to +re-acquire it, the attempt will succeed. + +Next, let's talk about why it doesn't work the way a reasonable person +would think it should work. + +Ideally, we'd have the ability to try to lock the resource tsl, and if +that fails, increment a counter of waiting processes, then block in the +kernel until the tsl is released. The process holding the resource tsl +would see the wait counter when it went to release the resource tsl, and +would wake any waiting processes up after releasing the lock. This would +actually require both another tsl (call it the mutex tsl) and +synchronization between the call that blocks in the kernel and the actual +resource tsl. The mutex tsl would be used to protect accesses to the +db_mutex_t itself. Locking the mutex tsl would be done by a busy loop, +which is safe because processes would never block holding that tsl (all +they would do is try to obtain the resource tsl and set/check the wait +count). The problem in this model is that the blocking call into the +kernel requires a blocking semaphore, i.e. one whose normal state is +locked. + +The only portable forms of locking under UNIX are fcntl(2) on a file +descriptor/offset, and System V semaphores. Neither of these locking +methods are sufficient to solve the problem. + +The problem with fcntl locking is that only the process that obtained the +lock can release it. Remember, we want the normal state of the kernel +semaphore to be locked. So, if the creator of the db_mutex_t were to +initialize the lock to "locked", then a second process locks the resource +tsl, and then a third process needs to block, waiting for the resource +tsl, when the second process wants to wake up the third process, it can't +because it's not the holder of the lock! For the second process to be +the holder of the lock, we would have to make a system call per +uncontested lock, which is what we were trying to get away from in the +first place. + +There are some hybrid schemes, such as signaling the holder of the lock, +or using a different blocking offset depending on which process is +holding the lock, but it gets complicated fairly quickly. I'm open to +suggestions, but I'm not holding my breath. + +Regardless, we use this form of locking when HAVE_SPINLOCKS is not +defined, (i.e. we're locking in the kernel) because it doesn't have the +limitations found in System V semaphores, and because the normal state of +the kernel object in that case is unlocked, so the process releasing the +lock is also the holder of the lock. + +The System V semaphore design has a number of other limitations that make +it inappropriate for this task. Namely: + +First, the semaphore key name space is separate from the file system name +space (although there exist methods for using file names to create +semaphore keys). If we use a well-known key, there's no reason to believe +that any particular key will not already be in use, either by another +instance of the DB application or some other application, in which case +the DB application will fail. If we create a key, then we have to use a +file system name to rendezvous and pass around the key. + +Second, System V semaphores traditionally have compile-time, system-wide +limits on the number of semaphore keys that you can have. Typically, that +number is far too low for any practical purpose. Since the semaphores +permit more than a single slot per semaphore key, we could try and get +around that limit by using multiple slots, but that means that the file +that we're using for rendezvous is going to have to contain slot +information as well as semaphore key information, and we're going to be +reading/writing it on every db_mutex_t init or destroy operation. Anyhow, +similar compile-time, system-wide limits on the numbers of slots per +semaphore key kick in, and you're right back where you started. + +My fantasy is that once POSIX.1 standard mutexes are in wide-spread use, +we can switch to them. My guess is that it won't happen, because the +POSIX semaphores are only required to work for threads within a process, +and not independent processes. + +Note: there are races in the statistics code, but since it's just that, +I didn't bother fixing them. (The fix requires a mutex tsl, so, when/if +this code is fixed to do rational locking (see above), then change the +statistics update code to acquire/release the mutex tsl. diff --git a/db2/mutex/alpha.dec b/db2/mutex/alpha.dec new file mode 100644 index 0000000000..83ed371136 --- /dev/null +++ b/db2/mutex/alpha.dec @@ -0,0 +1,25 @@ +/* + * @(#)alpha.dec 8.3 (Sleepycat Software) 1/18/97 + * + * The DEC C asm acts as a pseudo-call. The first argument is the assembly + * code, and the remaining arguments are assigned as in a procedure call, to + * r16, r17, etc. (represented in asm as %a0, %a1, and so forth). + * + * From: Dave Butenhof. + */ + +#include <c_asm.h> + +#define TSL_SET(tsl) (asm ("mb; \ + 10: ldl_l %v0,(%a0) ; \ + bne %v0,30f ; \ + or %v0,1,%r1 ; \ + stl_c %r1,(%a0) ; \ + beq %r1,20f ; \ + mb ; \ + br %r31,30f ; \ + 20: br %r31,10b ; \ + 30: ", (tsl))) + +THIS WAS NOT CONVERTED TO TAKE A POINTER AS AN ARGUMENT... +#define TSL_UNSET(tsl) (asm ("mb"), *(tsl) = 0) diff --git a/db2/mutex/alpha.gcc b/db2/mutex/alpha.gcc new file mode 100644 index 0000000000..247d04cf31 --- /dev/null +++ b/db2/mutex/alpha.gcc @@ -0,0 +1,52 @@ +/* + * @(#)alpha.gcc 10.1 (Sleepycat) 4/12/97 + * + * The code appearing below is taken from Richard L. Sites, ed. "Alpha + * Architecture Reference Manual", Digital Press, 1992, page 5-7 and 5-8. + * There are 2 modifications: + * + * 1. The jump from blbs __r1,30f to !__r1, which is dictated by the way the + * TSL_SET macro is used. The code suggested in Sites includes the main loop + * of the spin lock, whereas in this code the rest the loop is specified in C. + * The generated code might be suboptimal if the compiler generates a forward + * branch for the usual case in which the mutex is uncontested. + * + * 2. At label 20, Sites suggests including code for testing for an excessive + * number of _processor_ lock conflicts. (The seq_c instruction stores its + * first argument provided that no other processor has written to a byte range + * including its memory-location argument.) Absent such checking the code + * below could conceivably stall silently on a multiprocessor alpha, depending + * on how often processor/processor conflicts occur in a particular byte range. + * + * Note that the mb ("memory-barrier") instruction in TSL_UNSET is critical to + * correct operation in a multiprocessor alpha (as is, of course, the mb in + * the TSL_SET macro). Without the mb, changes to shared memory that occurred + * inside the critical section (before the TSL_UNSET) might reach shared memory + * _after_ the change of tsl to 0, thereby permitting another processor to see + * an inconsistent view of the data protected by the mutex. + * + * For gcc/alpha, 0 is clear, 1 is set. + */ +#define TSL_SET(tsl) ({ \ + register tsl_t *__l = (tsl); \ + register tsl_t __r1, __r2; \ + __asm__ volatile(" \n\ + 10: ldq_l %0,(%2) \n\ + blbs %0,30f \n\ + or %0,1,%1 \n\ + stq_c %1,(%2) \n\ + beq %1,20f \n\ + mb \n\ + br 30f \n\ + 20: br 10b \n\ + 30: " \ + : "=&r" (__r1), "=&r" (__r2) \ + : "r" (__l)); \ + !__r1; \ +}) + +#define TSL_UNSET(tsl) ({ \ + register tsl_t *__l = (tsl); \ + __asm__ volatile("mb; stq $31,(%0);" : : "r" (__l)); \ +}) +#define TSL_INIT(tsl) TSL_UNSET(tsl) diff --git a/db2/mutex/mutex.c b/db2/mutex/mutex.c new file mode 100644 index 0000000000..b23f738ad7 --- /dev/null +++ b/db2/mutex/mutex.c @@ -0,0 +1,280 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996, 1997 + * Sleepycat Software. All rights reserved. + */ + +#include "config.h" + +#ifndef lint +static const char sccsid[] = "@(#)mutex.c 10.22 (Sleepycat) 8/21/97"; +#endif /* not lint */ + +#ifndef NO_SYSTEM_INCLUDES +#include <sys/types.h> + +#include <errno.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#endif + +#include "db_int.h" +#include "common_ext.h" + +#ifdef HAVE_SPINLOCKS + +#ifdef HAVE_FUNC_AIX +#define TSL_INIT(x) +#define TSL_SET(x) (!_check_lock(x, 0, 1)) +#define TSL_UNSET(x) _clear_lock(x, 0) +#endif + +#ifdef HAVE_ASSEM_MC68020_GCC +#include "68020.gcc" +#endif + +#if defined(HAVE_FUNC_MSEM) +/* + * XXX + * Should we not use MSEM_IF_NOWAIT and let the system block for us? + * I've no idea if this will block all threads in the process or not. + */ +#define TSL_INIT(x) msem_init(x, MSEM_UNLOCKED) +#define TSL_SET(x) (!msem_lock(x, MSEM_IF_NOWAIT)) +#define TSL_UNSET(x) msem_unlock(x, 0) +#endif + +#ifdef HAVE_FUNC_SGI +#define TSL_INIT(x) init_lock(x) +#define TSL_SET(x) (!acquire_lock(x)) +#define TSL_UNSET(x) release_lock(x) +#endif + +#ifdef HAVE_FUNC_SOLARIS +/* + * Semaphore calls don't work on Solaris 5.5. + * + * #define TSL_INIT(x) sema_init(x, 1, USYNC_PROCESS, NULL) + * #define TSL_SET(x) (sema_wait(x) == 0) + * #define TSL_UNSET(x) sema_post(x) + */ +#define TSL_INIT(x) +#define TSL_SET(x) (_lock_try(x)) +#define TSL_UNSET(x) _lock_clear(x) +#endif + +#ifdef HAVE_ASSEM_SPARC_GCC +#include "sparc.gcc" +#endif + +#ifdef HAVE_ASSEM_UTS4_CC +#define TSL_INIT(x) +#define TSL_SET(x) (!uts_lock(x, 1)) +#define TSL_UNSET(x) (*(x) = 0) +#endif + +#ifdef HAVE_ASSEM_X86_GCC +#include "x86.gcc" +#endif + +#if defined(_WIN32) +/* DBDB this needs to be byte-aligned!! */ +#define TSL_INIT(tsl) +#define TSL_SET(tsl) (!InterlockedExchange((PLONG)tsl, 1)) +#define TSL_UNSET(tsl) (*(tsl) = 0) +#endif + +#ifdef macintosh +/* Mac spinlocks are simple because we cannot possibly be preempted. */ +#define TSL_INIT(tsl) +#define TSL_SET(tsl) (*(tsl) = 1) +#define TSL_UNSET(tsl) (*(tsl) = 0) +#endif + +#endif /* HAVE_SPINLOCKS */ + +#ifdef MORE_THAN_ONE_PROCESSOR +#define TSL_DEFAULT_SPINS 5 /* Default spins before block. */ +#else +#define TSL_DEFAULT_SPINS 1 /* Default spins before block. */ +#endif + +/* + * __db_mutex_init -- + * Initialize a DB mutex structure. + * + * PUBLIC: void __db_mutex_init __P((db_mutex_t *, off_t)); + */ +void +__db_mutex_init(mp, off) + db_mutex_t *mp; + off_t off; +{ +#ifdef DEBUG + if ((ALIGNTYPE)mp & (MUTEX_ALIGNMENT - 1)) { + (void)fprintf(stderr, + "MUTEX ERROR: mutex NOT %d-byte aligned!\n", + MUTEX_ALIGNMENT); + abort(); + } +#endif + memset(mp, 0, sizeof(db_mutex_t)); + +#ifdef HAVE_SPINLOCKS + TSL_INIT(&mp->tsl_resource); +#else + mp->off = off; +#endif +} + +#define MS(n) ((n) * 1000) /* Milliseconds to micro-seconds. */ +#define SECOND (MS(1000)) /* A second's worth of micro-seconds. */ + +/* + * __db_mutex_lock + * Lock on a mutex, logically blocking if necessary. + * + * PUBLIC: int __db_mutex_lock __P((db_mutex_t *, int, int (*)(void))); + */ +int +__db_mutex_lock(mp, fd, yield) + db_mutex_t *mp; + int fd; + int (*yield) __P((void)); +{ + u_long usecs; + +#ifdef HAVE_SPINLOCKS + int nspins; + + for (usecs = MS(10);;) { + /* + * Try and acquire the uncontested resource lock for + * TSL_DEFAULT_SPINS. + */ + for (nspins = TSL_DEFAULT_SPINS; nspins > 0; --nspins) + if (TSL_SET(&mp->tsl_resource)) { +#ifdef DEBUG + if (mp->pid != 0) { + (void)fprintf(stderr, + "MUTEX ERROR: __db_mutex_lock: lock currently locked\n"); + abort(); + } + mp->pid = getpid(); +#endif +#ifdef MUTEX_STATISTICS + if (usecs == MS(10)) + ++mp->mutex_set_nowait; + else + ++mp->mutex_set_wait; +#endif + return (0); + } + + /* Yield the processor; wait 10ms initially, up to 1 second. */ + if (yield == NULL || yield() != 0) { + (void)__db_sleep(0, usecs); + if ((usecs <<= 1) > SECOND) + usecs = SECOND; + } + } + /* NOTREACHED */ + +#else /* !HAVE_SPINLOCKS */ + struct flock k_lock; + pid_t mypid; + int locked; + + /* Initialize the lock. */ + k_lock.l_whence = SEEK_SET; + k_lock.l_start = mp->off; + k_lock.l_len = 1; + + for (locked = 0, mypid = getpid();;) { + /* + * Wait for the lock to become available; wait 10ms initially, + * up to 1 second. + */ + for (usecs = MS(10); mp->pid != 0;) + if (yield == NULL || yield() != 0) { + (void)__db_sleep(0, usecs); + if ((usecs <<= 1) > SECOND) + usecs = SECOND; + } + + /* Acquire an exclusive kernel lock. */ + k_lock.l_type = F_WRLCK; + if (fcntl(fd, F_SETLKW, &k_lock)) + return (1); + + /* If the resource tsl is still available, it's ours. */ + if (mp->pid == 0) { + locked = 1; + mp->pid = mypid; + } + + /* Release the kernel lock. */ + k_lock.l_type = F_UNLCK; + if (fcntl(fd, F_SETLK, &k_lock)) + return (1); + + /* + * If we got the resource tsl we're done. + * + * !!! + * We can't check to see if the lock is ours, because we may + * be trying to block ourselves in the lock manager, and so + * the holder of the lock that's preventing us from getting + * the lock may be us! (Seriously.) + */ + if (locked) + break; + } + +#ifdef MUTEX_STATISTICS + ++mp->mutex_set_wait; +#endif + return (0); +#endif /* !HAVE_SPINLOCKS */ +} + +/* + * __db_mutex_unlock -- + * Release a lock. + * + * PUBLIC: int __db_mutex_unlock __P((db_mutex_t *, int)); + */ +int +__db_mutex_unlock(mp, fd) + db_mutex_t *mp; + int fd; +{ +#ifdef DEBUG + if (mp->pid == 0) { + (void)fprintf(stderr, + "MUTEX ERROR: __db_mutex_unlock: lock already unlocked\n"); + abort(); + } +#endif + +#ifdef HAVE_SPINLOCKS +#ifdef DEBUG + mp->pid = 0; +#endif + + /* Release the resource tsl. */ + TSL_UNSET(&mp->tsl_resource); +#else + /* + * Release the resource tsl. We don't have to acquire any locks + * because processes trying to acquire the lock are checking for + * a pid of 0, not a specific value. + */ + mp->pid = 0; +#endif + return (0); +} diff --git a/db2/mutex/parisc.gcc b/db2/mutex/parisc.gcc new file mode 100644 index 0000000000..e15f6f2dba --- /dev/null +++ b/db2/mutex/parisc.gcc @@ -0,0 +1,40 @@ +/* + * @(#)parisc.gcc 8.5 (Sleepycat) 1/18/97 + * + * Copyright (c) 1996-1997, The University of Utah and the Computer Systems + * Laboratory at the University of Utah (CSL). All rights reserved. + * + * Permission to use, copy, modify and distribute this software is hereby + * granted provided that (1) source code retains these copyright, permission, + * and disclaimer notices, and (2) redistributions including binaries + * reproduce the notices in supporting documentation, and (3) all advertising + * materials mentioning features or use of this software display the following + * acknowledgement: ``This product includes software developed by the Computer + * Systems Laboratory at the University of Utah.'' + * + * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS + * IS" CONDITION. THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF + * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. + * + * CSL requests users of this software to return to csl-dist@cs.utah.edu any + * improvements that they make and grant CSL redistribution rights. + */ + +/* + * The PA-RISC has a "load and clear" instead of a "test and set" instruction. + * The 32-bit word used by that instruction must be 16-byte aligned hence we + * allocate 16 bytes for a tsl_t and use the word that is properly aligned. + * We could use the "aligned" attribute in GCC but that doesn't work for stack + * variables. + */ +#define TSL_SET(tsl) ({ \ + int *__l = (int *)(((int)(tsl)+15)&~15); \ + int __r; \ + asm volatile("ldcws 0(%1),%0" : "=r" (__r) : "r" (__l)); \ + __r & 1; \ +}) + +#define TSL_UNSET(tsl) ({ \ + int *__l = (int *)(((int)(tsl)+15)&~15); \ + *__l = -1; \ +}) diff --git a/db2/mutex/parisc.hp b/db2/mutex/parisc.hp new file mode 100644 index 0000000000..d10807b7f1 --- /dev/null +++ b/db2/mutex/parisc.hp @@ -0,0 +1,29 @@ +/* + * @(#)parisc.hp 8.5 (Sleepycat) 1/18/97 + * + * Copyright (c) 1996-1997, The University of Utah and the Computer Systems + * Laboratory at the University of Utah (CSL). All rights reserved. + * + * Permission to use, copy, modify and distribute this software is hereby + * granted provided that (1) source code retains these copyright, permission, + * and disclaimer notices, and (2) redistributions including binaries + * reproduce the notices in supporting documentation, and (3) all advertising + * materials mentioning features or use of this software display the following + * acknowledgement: ``This product includes software developed by the Computer + * Systems Laboratory at the University of Utah.'' + * + * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS + * IS" CONDITION. THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF + * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. + * + * CSL requests users of this software to return to csl-dist@cs.utah.edu any + * improvements that they make and grant CSL redistribution rights. + */ + +/* + * The PA-RISC has a "load and clear" instead of a "test and set" instruction. + * The 32-bit word used by that instruction must be 16-byte aligned hence we + * allocate 16 bytes for a tsl_t and use the word that is properly aligned. + */ +#define TSL_SET(tsl) tsl_set(tsl) +#define TSL_UNSET(tsl) tsl_unset(tsl) diff --git a/db2/mutex/sparc.gcc b/db2/mutex/sparc.gcc new file mode 100644 index 0000000000..8445a0629b --- /dev/null +++ b/db2/mutex/sparc.gcc @@ -0,0 +1,33 @@ +/* + * @(#)sparc.gcc 10.1 (Sleepycat) 4/12/97 + * + * The ldstub instruction takes the location specified by its first argument + * (a register containing a memory address) and loads its contents into its + * second argument (a register) and atomically sets the contents the location + * specified by its first argument to a byte of 1s. (The value in the second + * argument is never read, but only overwritten.) + * + * The membar instructions are needed to ensure that writes to the lock are + * correctly ordered with writes that occur later in the instruction stream. + * + * For gcc/sparc, 0 is clear, 1 is set. + */ + +#if defined(__sparcv9__) +Does the following code need membar instructions for V9 processors? +#endif + +#define TSL_SET(tsl) ({ \ + register tsl_t *__l = (tsl); \ + register tsl_t __r; \ + __asm__ volatile \ + ("ldstub [%1],%0" \ + : "=r"( __r) : "r" (__l)); \ + !__r; \ +}) + +#define TSL_UNSET(tsl) ({ \ + register tsl_t *__l = (tsl); \ + __asm__ volatile ("stb %%g0,[%0]" : : "r" (__l)); \ +}) +#define TSL_INIT(tsl) TSL_UNSET(tsl) diff --git a/db2/mutex/uts4.cc.s b/db2/mutex/uts4.cc.s new file mode 100644 index 0000000000..ee5f4143bd --- /dev/null +++ b/db2/mutex/uts4.cc.s @@ -0,0 +1,21 @@ + / + / int uts_lock ( int *p, int i ); + / Update the lock word pointed to by p with the + / value i, using compare-and-swap. + / Returns 0 if update was successful. + / Returns 1 if update failed. + / + entry uts_lock + uts_lock: + using .,r15 + st r2,8(sp) / Save R2 + l r2,64+0(sp) / R2 -> word to update + slr r0, r0 / R0 = current lock value must be 0 + l r1,64+4(sp) / R1 = new lock value + cs r0,r1,0(r2) / Try the update ... + be x / ... Success. Return 0 + la r0,1 / ... Failure. Return 1 + x: / + l r2,8(sp) / Restore R2 + b 2(,r14) / Return to caller + drop r15 diff --git a/db2/mutex/x86.gcc b/db2/mutex/x86.gcc new file mode 100644 index 0000000000..886a6811a2 --- /dev/null +++ b/db2/mutex/x86.gcc @@ -0,0 +1,17 @@ +/* + * @(#)x86.gcc 10.2 (Sleepycat) 6/21/97 + * + * For gcc/x86, 0 is clear, 1 is set. + */ +#define TSL_SET(tsl) ({ \ + register tsl_t *__l = (tsl); \ + int __r; \ + asm volatile("movl $1,%%eax; xchgb %1,%%al; xorl $1,%%eax" \ + : "=&a" (__r), "=m" (*__l) \ + : "1" (*__l) \ + ); \ + __r & 1; \ +}) + +#define TSL_UNSET(tsl) (*(tsl) = 0) +#define TSL_INIT(tsl) TSL_UNSET(tsl) |