On 2011-02-21 09:43, Paolo Bonzini wrote:
> These are already present in the Win32 implementation, add them to
> the pthread wrappers as well.
>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> qemu-thread-posix.c | 27 +++++++++++++++++++++++++--
> qemu-thread-posix.h | 1 +
> 2 files changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/qemu-thread-posix.c b/qemu-thread-posix.c
> index 28b3f80..2176f81 100644
> --- a/qemu-thread-posix.c
> +++ b/qemu-thread-posix.c
> @@ -16,9 +16,12 @@
> #include <time.h>
> #include <signal.h>
> #include <stdint.h>
> +#include <assert.h>
> #include <string.h>
> #include "qemu-thread.h"
>
> +static pthread_t pthread_null;
> +
> static void error_exit(int err, const char *msg)
> {
> fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
> @@ -28,8 +31,13 @@ static void error_exit(int err, const char *msg)
> void qemu_mutex_init(QemuMutex *mutex)
> {
> int err;
> + pthread_mutexattr_t mutexattr;
>
> - err = pthread_mutex_init(&mutex->lock, NULL);
> + mutex->owner = pthread_null;
> + pthread_mutexattr_init(&mutexattr);
> + pthread_mutexattr_settype(&mutexattr, PTHREAD_MUTEX_ERRORCHECK);
> + err = pthread_mutex_init(&mutex->lock, &mutexattr);
> + pthread_mutexattr_destroy(&mutexattr);
> if (err)
> error_exit(err, __func__);
> }
> @@ -48,13 +56,20 @@ void qemu_mutex_lock(QemuMutex *mutex)
> int err;
>
> err = pthread_mutex_lock(&mutex->lock);
> + mutex->owner = pthread_self();
> if (err)
> error_exit(err, __func__);
> }
>
> int qemu_mutex_trylock(QemuMutex *mutex)
> {
> - return pthread_mutex_trylock(&mutex->lock);
> + int err;
> + err = pthread_mutex_trylock(&mutex->lock);
> + if (err == 0) {
> + mutex->owner = pthread_self();
> + }
> +
> + return !!err;
> }
>
> static void timespec_add_ms(struct timespec *ts, uint64_t msecs)
> @@ -85,6 +100,11 @@ void qemu_mutex_unlock(QemuMutex *mutex)
> {
> int err;
>
> + /* An EDEADLOCK would arrive after we reset the owner. So this
> + assert is for ease of debugging (it lets you see what is the
> + actual owner. */
Don't get this. Why do you want to avoid the proper error detection of
pthread?
> + assert(pthread_equal(mutex->owner, pthread_self()));
> + mutex->owner = pthread_null;
> err = pthread_mutex_unlock(&mutex->lock);
> if (err)
> error_exit(err, __func__);
> @@ -130,7 +150,10 @@ void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
> {
> int err;
>
> + assert(pthread_equal(mutex->owner, pthread_self()));
> + mutex->owner = pthread_null;
> err = pthread_cond_wait(&cond->cond, &mutex->lock);
> + mutex->owner = pthread_self();
> if (err)
> error_exit(err, __func__);
> }
> diff --git a/qemu-thread-posix.h b/qemu-thread-posix.h
> index 7af371c..11978db 100644
> --- a/qemu-thread-posix.h
> +++ b/qemu-thread-posix.h
> @@ -4,6 +4,7 @@
>
> struct QemuMutex {
> pthread_mutex_t lock;
> + pthread_t owner;
> };
>
> struct QemuCond {
You said that you want to add owner tracking for assertion in
cond_signal/broadcast. That's OK. But the assertions in the mutex layer
are redundant for PTHREAD_MUTEX_ERRORCHECK - unless I'm missing
something now.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
