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[Qemu-devel] Re: [PATCH 07/21] add assertions on the owner of a QemuMute
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH 07/21] add assertions on the owner of a QemuMutex |
Date: |
Mon, 21 Feb 2011 10:50:14 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
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 <address@hidden>
> ---
> 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
- [Qemu-devel] [PATCH uq/master 00/21] Win32 iothread support, Paolo Bonzini, 2011/02/21
- [Qemu-devel] [PATCH 01/21] unlock iothread during WaitForMultipleObjects, Paolo Bonzini, 2011/02/21
- [Qemu-devel] [PATCH 02/21] implement win32 dynticks timer, Paolo Bonzini, 2011/02/21
- [Qemu-devel] [PATCH 04/21] replace qemu_thread_equal API with qemu_thread_is_current, Paolo Bonzini, 2011/02/21
- [Qemu-devel] [PATCH 05/21] add win32 qemu-thread implementation, Paolo Bonzini, 2011/02/21
- [Qemu-devel] [PATCH 06/21] include qemu-thread.h early, Paolo Bonzini, 2011/02/21
- [Qemu-devel] [PATCH 03/21] use win32 timer queues, Paolo Bonzini, 2011/02/21
- [Qemu-devel] [PATCH 07/21] add assertions on the owner of a QemuMutex, Paolo Bonzini, 2011/02/21
- [Qemu-devel] Re: [PATCH 07/21] add assertions on the owner of a QemuMutex,
Jan Kiszka <=
[Qemu-devel] [PATCH 08/21] remove CONFIG_THREAD, Paolo Bonzini, 2011/02/21
[Qemu-devel] [PATCH 09/21] inline cpu_halted into sole caller, Paolo Bonzini, 2011/02/21
[Qemu-devel] [PATCH 11/21] exit round-robin vcpu loop if cpu->stopped is true, Paolo Bonzini, 2011/02/21
[Qemu-devel] [PATCH 12/21] always signal pause_cond after stopping a VCPU, Paolo Bonzini, 2011/02/21
[Qemu-devel] [PATCH 13/21] do not use timedwait on qemu_halt_cond, Paolo Bonzini, 2011/02/21
[Qemu-devel] [PATCH 10/21] always qemu_cpu_kick after unhalting a cpu, Paolo Bonzini, 2011/02/21