diff mbox series

[v1,1/5] Add a mutex to guarantee single writer to qemu_logfile handle.

Message ID 20191112150105.2498-2-robert.foley@linaro.org
State New
Headers show
Series Make the qemu_logfile handle thread safe. | expand

Commit Message

Robert Foley Nov. 12, 2019, 3:01 p.m. UTC 
Also added qemu_logfile_init() for initializing the logfile mutex.

Signed-off-by: Robert Foley <robert.foley@linaro.org>

---
v1
    - changed qemu_logfile_init() to use __constructor__.
---
 util/log.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

-- 
2.17.1

Comments

Alex Bennée Nov. 12, 2019, 5:09 p.m. UTC | #1 
Robert Foley <robert.foley@linaro.org> writes:

> Also added qemu_logfile_init() for initializing the logfile mutex.

>

> Signed-off-by: Robert Foley <robert.foley@linaro.org>


Reviewed-by: Alex Bennée <alex.bennee@linaro.org>


> ---

> v1

>     - changed qemu_logfile_init() to use __constructor__.

> ---

>  util/log.c | 14 ++++++++++++++

>  1 file changed, 14 insertions(+)

>

> diff --git a/util/log.c b/util/log.c

> index 1ca13059ee..c25643dc99 100644

> --- a/util/log.c

> +++ b/util/log.c

> @@ -24,8 +24,10 @@

>  #include "qapi/error.h"

>  #include "qemu/cutils.h"

>  #include "trace/control.h"

> +#include "qemu/thread.h"

>

>  static char *logfilename;

> +static QemuMutex qemu_logfile_mutex;

>  FILE *qemu_logfile;

>  int qemu_loglevel;

>  static int log_append = 0;

> @@ -49,6 +51,11 @@ int qemu_log(const char *fmt, ...)

>      return ret;

>  }

>

> +static void __attribute__((__constructor__)) qemu_logfile_init(void)

> +{

> +    qemu_mutex_init(&qemu_logfile_mutex);

> +}

> +

>  static bool log_uses_own_buffers;

>

>  /* enable or disable low levels log */

> @@ -58,6 +65,9 @@ void qemu_set_log(int log_flags)

>  #ifdef CONFIG_TRACE_LOG

>      qemu_loglevel |= LOG_TRACE;

>  #endif

> +

> +    g_assert(qemu_logfile_mutex.initialized);

> +    qemu_mutex_lock(&qemu_logfile_mutex);

>      if (!qemu_logfile &&

>          (is_daemonized() ? logfilename != NULL : qemu_loglevel)) {

>          if (logfilename) {

> @@ -93,6 +103,7 @@ void qemu_set_log(int log_flags)

>              log_append = 1;

>          }

>      }

> +    qemu_mutex_unlock(&qemu_logfile_mutex);

>      if (qemu_logfile &&

>          (is_daemonized() ? logfilename == NULL : !qemu_loglevel)) {

>          qemu_log_close();

> @@ -230,12 +241,15 @@ void qemu_log_flush(void)

>  /* Close the log file */

>  void qemu_log_close(void)

>  {

> +    g_assert(qemu_logfile_mutex.initialized);

> +    qemu_mutex_lock(&qemu_logfile_mutex);

>      if (qemu_logfile) {

>          if (qemu_logfile != stderr) {

>              fclose(qemu_logfile);

>          }

>          qemu_logfile = NULL;

>      }

> +    qemu_mutex_unlock(&qemu_logfile_mutex);

>  }

>

>  const QEMULogItem qemu_log_items[] = {



--
Alex Bennée
Richard Henderson Nov. 16, 2019, 11:57 a.m. UTC | #2 
On 11/12/19 4:01 PM, Robert Foley wrote:
> Also added qemu_logfile_init() for initializing the logfile mutex.

> 

> Signed-off-by: Robert Foley <robert.foley@linaro.org>

> ---

> v1

>     - changed qemu_logfile_init() to use __constructor__.

> ---

>  util/log.c | 14 ++++++++++++++

>  1 file changed, 14 insertions(+)

> 

> diff --git a/util/log.c b/util/log.c

> index 1ca13059ee..c25643dc99 100644

> --- a/util/log.c

> +++ b/util/log.c

> @@ -24,8 +24,10 @@

>  #include "qapi/error.h"

>  #include "qemu/cutils.h"

>  #include "trace/control.h"

> +#include "qemu/thread.h"

>  

>  static char *logfilename;

> +static QemuMutex qemu_logfile_mutex;

>  FILE *qemu_logfile;

>  int qemu_loglevel;

>  static int log_append = 0;

> @@ -49,6 +51,11 @@ int qemu_log(const char *fmt, ...)

>      return ret;

>  }

>  

> +static void __attribute__((__constructor__)) qemu_logfile_init(void)

> +{

> +    qemu_mutex_init(&qemu_logfile_mutex);

> +}

> +

>  static bool log_uses_own_buffers;

>  

>  /* enable or disable low levels log */

> @@ -58,6 +65,9 @@ void qemu_set_log(int log_flags)

>  #ifdef CONFIG_TRACE_LOG

>      qemu_loglevel |= LOG_TRACE;

>  #endif

> +

> +    g_assert(qemu_logfile_mutex.initialized);


Why the asserts?

If you want a runtime test, then use the test to initialize it.
Otherwise, trust the constructor.


r~
Robert Foley Nov. 18, 2019, 12:39 p.m. UTC | #3 
> > +

> > +    g_assert(qemu_logfile_mutex.initialized);

>

> Why the asserts?

>

> If you want a runtime test, then use the test to initialize it.

> Otherwise, trust the constructor.

>

I see your point here.   We can/should just trust the constructor.
Will remove the mutex.initialized asserts.

Thanks,
-Rob

On Sat, 16 Nov 2019 at 06:58, Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> On 11/12/19 4:01 PM, Robert Foley wrote:

> > Also added qemu_logfile_init() for initializing the logfile mutex.

> >

> > Signed-off-by: Robert Foley <robert.foley@linaro.org>

> > ---

> > v1

> >     - changed qemu_logfile_init() to use __constructor__.

> > ---

> >  util/log.c | 14 ++++++++++++++

> >  1 file changed, 14 insertions(+)

> >

> > diff --git a/util/log.c b/util/log.c

> > index 1ca13059ee..c25643dc99 100644

> > --- a/util/log.c

> > +++ b/util/log.c

> > @@ -24,8 +24,10 @@

> >  #include "qapi/error.h"

> >  #include "qemu/cutils.h"

> >  #include "trace/control.h"

> > +#include "qemu/thread.h"

> >

> >  static char *logfilename;

> > +static QemuMutex qemu_logfile_mutex;

> >  FILE *qemu_logfile;

> >  int qemu_loglevel;

> >  static int log_append = 0;

> > @@ -49,6 +51,11 @@ int qemu_log(const char *fmt, ...)

> >      return ret;

> >  }

> >

> > +static void __attribute__((__constructor__)) qemu_logfile_init(void)

> > +{

> > +    qemu_mutex_init(&qemu_logfile_mutex);

> > +}

> > +

> >  static bool log_uses_own_buffers;

> >

> >  /* enable or disable low levels log */

> > @@ -58,6 +65,9 @@ void qemu_set_log(int log_flags)

> >  #ifdef CONFIG_TRACE_LOG

> >      qemu_loglevel |= LOG_TRACE;

> >  #endif

> > +

> > +    g_assert(qemu_logfile_mutex.initialized);

>

> Why the asserts?

>

> If you want a runtime test, then use the test to initialize it.

> Otherwise, trust the constructor.

>

>

> r~
diff mbox series

Patch

diff --git a/util/log.c b/util/log.c
index 1ca13059ee..c25643dc99 100644
--- a/util/log.c
+++ b/util/log.c
@@ -24,8 +24,10 @@ 
 #include "qapi/error.h"
 #include "qemu/cutils.h"
 #include "trace/control.h"
+#include "qemu/thread.h"
 
 static char *logfilename;
+static QemuMutex qemu_logfile_mutex;
 FILE *qemu_logfile;
 int qemu_loglevel;
 static int log_append = 0;
@@ -49,6 +51,11 @@  int qemu_log(const char *fmt, ...)
     return ret;
 }
 
+static void __attribute__((__constructor__)) qemu_logfile_init(void)
+{
+    qemu_mutex_init(&qemu_logfile_mutex);
+}
+
 static bool log_uses_own_buffers;
 
 /* enable or disable low levels log */
@@ -58,6 +65,9 @@  void qemu_set_log(int log_flags)
 #ifdef CONFIG_TRACE_LOG
     qemu_loglevel |= LOG_TRACE;
 #endif
+
+    g_assert(qemu_logfile_mutex.initialized);
+    qemu_mutex_lock(&qemu_logfile_mutex);
     if (!qemu_logfile &&
         (is_daemonized() ? logfilename != NULL : qemu_loglevel)) {
         if (logfilename) {
@@ -93,6 +103,7 @@  void qemu_set_log(int log_flags)
             log_append = 1;
         }
     }
+    qemu_mutex_unlock(&qemu_logfile_mutex);
     if (qemu_logfile &&
         (is_daemonized() ? logfilename == NULL : !qemu_loglevel)) {
         qemu_log_close();
@@ -230,12 +241,15 @@  void qemu_log_flush(void)
 /* Close the log file */
 void qemu_log_close(void)
 {
+    g_assert(qemu_logfile_mutex.initialized);
+    qemu_mutex_lock(&qemu_logfile_mutex);
     if (qemu_logfile) {
         if (qemu_logfile != stderr) {
             fclose(qemu_logfile);
         }
         qemu_logfile = NULL;
     }
+    qemu_mutex_unlock(&qemu_logfile_mutex);
 }
 
 const QEMULogItem qemu_log_items[] = {