Index: uspace/lib/libc/arch/amd64/include/atomic.h =================================================================== --- uspace/lib/libc/arch/amd64/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/amd64/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -37,4 +37,8 @@ #ifndef LIBC_amd64_ATOMIC_H_ #define LIBC_amd64_ATOMIC_H_ + +#define LIBC_ARCH_ATOMIC_H_ + +#include static inline void atomic_inc(atomic_t *val) { Index: uspace/lib/libc/arch/arm32/include/atomic.h =================================================================== --- uspace/lib/libc/arch/arm32/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/arm32/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -37,4 +37,30 @@ #define LIBC_arm32_ATOMIC_H_ +#include + +typedef struct atomic { + volatile long count; +} atomic_t; + +static inline void atomic_set(atomic_t *val, long i) +{ + val->count = i; +} + +static inline long atomic_get(atomic_t *val) +{ + return val->count; +} + +static inline bool cas(atomic_t *val, long ov, long nv) +{ + /* FIXME: is not atomic */ + if (val->count == ov) { + val->count = nv; + return true; + } + return false; +} + /** Atomic addition. * @@ -49,4 +75,5 @@ volatile long * mem = &(val->count); + /* FIXME: is not atomic, is broken */ asm volatile ( "1:\n" Index: uspace/lib/libc/arch/ia32/Makefile.inc =================================================================== --- uspace/lib/libc/arch/ia32/Makefile.inc (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/ia32/Makefile.inc (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -39,4 +39,5 @@ arch/$(UARCH)/src/setjmp.S +GCC_CFLAGS += -march=pentium LFLAGS += -N Index: uspace/lib/libc/arch/ia32/include/atomic.h =================================================================== --- uspace/lib/libc/arch/ia32/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/ia32/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -35,4 +35,8 @@ #ifndef LIBC_ia32_ATOMIC_H_ #define LIBC_ia32_ATOMIC_H_ + +#define LIBC_ARCH_ATOMIC_H_ + +#include static inline void atomic_inc(atomic_t *val) { Index: uspace/lib/libc/arch/ia64/include/atomic.h =================================================================== --- uspace/lib/libc/arch/ia64/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/ia64/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -35,4 +35,8 @@ #ifndef LIBC_ia64_ATOMIC_H_ #define LIBC_ia64_ATOMIC_H_ + +#define LIBC_ARCH_ATOMIC_H_ + +#include static inline void atomic_inc(atomic_t *val) Index: uspace/lib/libc/arch/mips32/include/atomic.h =================================================================== --- uspace/lib/libc/arch/mips32/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/mips32/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -36,4 +36,8 @@ #ifndef LIBC_mips32_ATOMIC_H_ #define LIBC_mips32_ATOMIC_H_ + +#define LIBC_ARCH_ATOMIC_H_ + +#include #define atomic_inc(x) ((void) atomic_add(x, 1)) Index: uspace/lib/libc/arch/ppc32/include/atomic.h =================================================================== --- uspace/lib/libc/arch/ppc32/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/ppc32/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -35,4 +35,8 @@ #ifndef LIBC_ppc32_ATOMIC_H_ #define LIBC_ppc32_ATOMIC_H_ + +#define LIBC_ARCH_ATOMIC_H_ + +#include static inline void atomic_inc(atomic_t *val) Index: uspace/lib/libc/arch/sparc64/include/atomic.h =================================================================== --- uspace/lib/libc/arch/sparc64/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/arch/sparc64/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -36,4 +36,7 @@ #define LIBC_sparc64_ATOMIC_H_ +#define LIBC_ARCH_ATOMIC_H_ + +#include #include Index: uspace/lib/libc/generic/futex.c =================================================================== --- uspace/lib/libc/generic/futex.c (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/generic/futex.c (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -36,49 +36,5 @@ #include #include -#include #include -#include - -/* - * Note about race conditions. - * Because of non-atomic nature of operations performed sequentially on the - * futex counter and the futex wait queue, there is a race condition: - * - * (wq->missed_wakeups == 1) && (futex->count = 1) - * - * Scenario 1 (wait queue timeout vs. futex_up()): - * 1. assume wq->missed_wakeups == 0 && futex->count == -1 - * (ie. thread A sleeping, thread B in the critical section) - * 2. A receives timeout and gets removed from the wait queue - * 3. B wants to leave the critical section and calls futex_up() - * 4. B thus changes futex->count from -1 to 0 - * 5. B has to call SYS_FUTEX_WAKEUP syscall to wake up the sleeping thread - * 6. B finds the wait queue empty and changes wq->missed_wakeups from 0 to 1 - * 7. A fixes futex->count (i.e. the number of waiting threads) by changing it - * from 0 to 1 - * - * Scenario 2 (conditional down operation vs. futex_up) - * 1. assume wq->missed_wakeups == 0 && futex->count == 0 - * (i.e. thread A is in the critical section) - * 2. thread B performs futex_trydown() operation and changes futex->count from - * 0 to -1 - * B is now obliged to call SYS_FUTEX_SLEEP syscall - * 3. A wants to leave the critical section and does futex_up() - * 4. A thus changes futex->count from -1 to 0 and must call SYS_FUTEX_WAKEUP - * syscall - * 5. B finds the wait queue empty and immediatelly aborts the conditional sleep - * 6. No thread is queueing in the wait queue so wq->missed_wakeups changes from - * 0 to 1 - * 6. B fixes futex->count (i.e. the number of waiting threads) by changing it - * from 0 to 1 - * - * Both scenarios allow two threads to be in the critical section - * simultaneously. One without kernel intervention and the other through - * wq->missed_wakeups being 1. - * - * To mitigate this problem, futex_down_timeout() detects that the syscall - * didn't sleep in the wait queue, fixes the futex counter and RETRIES the - * whole operation again. - */ /** Initialize futex counter. @@ -92,81 +48,28 @@ } -int futex_down(futex_t *futex) -{ - return futex_down_timeout(futex, SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE); -} - -int futex_trydown(futex_t *futex) -{ - return futex_down_timeout(futex, SYNCH_NO_TIMEOUT, - SYNCH_FLAGS_NON_BLOCKING); -} - /** Try to down the futex. * * @param futex Futex. - * @param usec Microseconds to wait. Zero value means sleep without - * timeout. - * @param flags Select mode of operation. See comment for - * waitq_sleep_timeout(). + * @return Non-zero if the futex was acquired. + * @return Zero if the futex was not acquired. + */ +int futex_trydown(futex_t *futex) +{ + return cas(futex, 1, 0); +} + +/** Down the futex. * - * @return ENOENT if there is no such virtual address. One of - * ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED on success or - * ESYNCH_TIMEOUT if the lock was not acquired because of - * a timeout or ESYNCH_WOULD_BLOCK if the operation could - * not be carried out atomically (if requested so). + * @param futex Futex. + * @return ENOENT if there is no such virtual address. + * @return Zero in the uncontended case. + * @return Otherwise one of ESYNCH_OK_ATOMIC or ESYNCH_OK_BLOCKED. */ -int futex_down_timeout(futex_t *futex, uint32_t usec, int flags) +int futex_down(futex_t *futex) { - int rc; - - while (atomic_predec(futex) < 0) { - rc = __SYSCALL3(SYS_FUTEX_SLEEP, (sysarg_t) &futex->count, - (sysarg_t) usec, (sysarg_t) flags); - - switch (rc) { - case ESYNCH_OK_ATOMIC: - /* - * Because of a race condition between timeout and - * futex_up() and between conditional - * futex_down_timeout() and futex_up(), we have to give - * up and try again in this special case. - */ - atomic_inc(futex); - break; + if (atomic_predec(futex) < 0) + return __SYSCALL1(SYS_FUTEX_SLEEP, (sysarg_t) &futex->count); - case ESYNCH_TIMEOUT: - atomic_inc(futex); - return ESYNCH_TIMEOUT; - break; - - case ESYNCH_WOULD_BLOCK: - /* - * The conditional down operation should be implemented - * this way. The userspace-only variant tends to - * accumulate missed wakeups in the kernel futex wait - * queue. - */ - atomic_inc(futex); - return ESYNCH_WOULD_BLOCK; - break; - - case ESYNCH_OK_BLOCKED: - /* - * Enter the critical section. - * The futex counter has already been incremented for - * us. - */ - return ESYNCH_OK_BLOCKED; - break; - default: - return rc; - } - } - - /* - * Enter the critical section. - */ - return ESYNCH_OK_ATOMIC; + return 0; } @@ -174,14 +77,10 @@ * * @param futex Futex. - * - * @return ENOENT if there is no such virtual address. Otherwise - * zero. + * @return ENOENT if there is no such virtual address. + * @return Zero in the uncontended case. */ int futex_up(futex_t *futex) { - long val; - - val = atomic_postinc(futex); - if (val < 0) + if (atomic_postinc(futex) < 0) return __SYSCALL1(SYS_FUTEX_WAKEUP, (sysarg_t) &futex->count); Index: uspace/lib/libc/generic/io/io.c =================================================================== --- uspace/lib/libc/generic/io/io.c (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/generic/io/io.c (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -341,9 +341,14 @@ size_t fread(void *buf, size_t size, size_t nmemb, FILE *stream) { - size_t left = size * nmemb; - size_t done = 0; - + size_t left, done; + + if (size == 0 || nmemb == 0) + return 0; + /* Make sure no data is pending write. */ _fflushbuf(stream); + + left = size * nmemb; + done = 0; while ((left > 0) && (!stream->error) && (!stream->eof)) { @@ -365,7 +370,13 @@ static size_t _fwrite(const void *buf, size_t size, size_t nmemb, FILE *stream) { - size_t left = size * nmemb; - size_t done = 0; - + size_t left; + size_t done; + + if (size == 0 || nmemb == 0) + return 0; + + left = size * nmemb; + done = 0; + while ((left > 0) && (!stream->error)) { ssize_t wr; @@ -421,5 +432,8 @@ uint8_t b; bool need_flush; - + + if (size == 0 || nmemb == 0) + return 0; + /* If not buffered stream, write out directly. */ if (stream->btype == _IONBF) { Index: uspace/lib/libc/generic/time.c =================================================================== --- uspace/lib/libc/generic/time.c (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/generic/time.c (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -31,5 +31,5 @@ */ /** @file - */ + */ #include @@ -40,7 +40,7 @@ #include #include -#include #include #include +#include #include @@ -189,27 +189,20 @@ /** Wait unconditionally for specified number of microseconds */ -int usleep(unsigned long usec) -{ - atomic_t futex = FUTEX_INITIALIZER; - - futex_initialize(&futex, 0); - futex_down_timeout(&futex, usec, 0); +int usleep(useconds_t usec) +{ + (void) __SYSCALL1(SYS_THREAD_USLEEP, usec); return 0; } /** Wait unconditionally for specified number of seconds */ -unsigned int sleep(unsigned int seconds) -{ - atomic_t futex = FUTEX_INITIALIZER; - - futex_initialize(&futex, 0); - +unsigned int sleep(unsigned int sec) +{ /* Sleep in 1000 second steps to support full argument range */ - while (seconds > 0) { - unsigned int period = (seconds > 1000) ? 1000 : seconds; + while (sec > 0) { + unsigned int period = (sec > 1000) ? 1000 : sec; - futex_down_timeout(&futex, period * 1000000, 0); - seconds -= period; + usleep(period * 1000000); + sec -= period; } return 0; Index: uspace/lib/libc/include/atomic.h =================================================================== --- uspace/lib/libc/include/atomic.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/include/atomic.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -1,4 +1,4 @@ /* - * Copyright (c) 2006 Jakub Jermar + * Copyright (c) 2009 Jakub Jermar * All rights reserved. * @@ -36,19 +36,5 @@ #define LIBC_ATOMIC_H_ -typedef struct atomic { - volatile long count; -} atomic_t; - #include - -static inline void atomic_set(atomic_t *val, long i) -{ - val->count = i; -} - -static inline long atomic_get(atomic_t *val) -{ - return val->count; -} #endif Index: uspace/lib/libc/include/atomicdflt.h =================================================================== --- uspace/lib/libc/include/atomicdflt.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) +++ uspace/lib/libc/include/atomicdflt.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -0,0 +1,66 @@ +/* + * Copyright (c) 2006 Jakub Jermar + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * - The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/** @addtogroup libc + * @{ + */ +/** @file + */ + +#ifndef LIBC_ATOMICDFLT_H_ +#define LIBC_ATOMICDFLT_H_ + +#ifndef LIBC_ARCH_ATOMIC_H_ +#error This file cannot be included directly, include atomic.h instead. +#endif + +#include + +typedef struct atomic { + volatile long count; +} atomic_t; + +static inline void atomic_set(atomic_t *val, long i) +{ + val->count = i; +} + +static inline long atomic_get(atomic_t *val) +{ + return val->count; +} + +static inline bool cas(atomic_t *val, long ov, long nv) +{ + return __sync_bool_compare_and_swap(&val->count, ov, nv); +} + +#endif + +/** @} + */ Index: uspace/lib/libc/include/futex.h =================================================================== --- uspace/lib/libc/include/futex.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/include/futex.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -46,5 +46,4 @@ extern int futex_down(futex_t *futex); extern int futex_trydown(futex_t *futex); -extern int futex_down_timeout(futex_t *futex, uint32_t usec, int flags); extern int futex_up(futex_t *futex); Index: uspace/lib/libc/include/unistd.h =================================================================== --- uspace/lib/libc/include/unistd.h (revision 2a5af223633736d7b866a2f1a951142fe72dc78b) +++ uspace/lib/libc/include/unistd.h (revision 034bf0e27f6439c8ee9425abd454c308f7f0ea84) @@ -51,4 +51,6 @@ #endif +typedef uint32_t useconds_t; + extern int dup2(int oldfd, int newfd); @@ -68,6 +70,6 @@ extern void _exit(int status) __attribute__ ((noreturn)); -extern int usleep(unsigned long usec); -extern unsigned int sleep(unsigned int seconds); +extern int usleep(useconds_t uses); +extern unsigned int sleep(unsigned int se); #endif