Patchwork [v1,1/3] : Move the paio_signal_handler to a generic location.

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Submitter Arun Bharadwaj
Date March 15, 2011, 10:36 a.m.
Message ID <20110315103626.GB23922@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/86936/
State New
Headers show

Comments

Arun Bharadwaj - March 15, 2011, 10:36 a.m.
* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2011-03-15 16:04:53]:

Author: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Date:   Thu Mar 10 14:45:25 2011 +0530

    Move the paio_signal_handler to a generic location.
    
    The paio subsystem uses the signal, SIGUSR2. So move
    the signal handler to a more generic place such that
    other subsystems like 9pfs can also use it.
    
    TODO: I have moved the signal handler code to
    qemu-thread.c, which is NOT the right place. I need
    suggestions as to where is the right place to put it.
    
    Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
    Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Stefan Hajnoczi - March 15, 2011, 11:38 a.m.
On Tue, Mar 15, 2011 at 10:36 AM, Arun R Bharadwaj
<arun@linux.vnet.ibm.com> wrote:
> * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2011-03-15 16:04:53]:
>
> Author: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
> Date:   Thu Mar 10 14:45:25 2011 +0530
>
>    Move the paio_signal_handler to a generic location.
>
>    The paio subsystem uses the signal, SIGUSR2. So move
>    the signal handler to a more generic place such that
>    other subsystems like 9pfs can also use it.
>
>    TODO: I have moved the signal handler code to
>    qemu-thread.c, which is NOT the right place. I need
>    suggestions as to where is the right place to put it.

I think os-posix.c would be appropriate.  Please check how this
affects Windows host and linux-user builds.

> @@ -356,6 +359,15 @@ static void *aio_thread(void *unused)
>         idle_threads++;
>         mutex_unlock(&lock);
>
> +        if (posix_aio_state) {

If we get here posix_aio_state must be non-NULL.  Please remove the check.

> +void sigusr2_signal_handler(int signum)

static void sigusr2_signal_handler(int signum)

Stefan
Arun Bharadwaj - March 15, 2011, 3:27 p.m.
* Stefan Hajnoczi <stefanha@gmail.com> [2011-03-15 11:38:03]:

> On Tue, Mar 15, 2011 at 10:36 AM, Arun R Bharadwaj
> <arun@linux.vnet.ibm.com> wrote:
> > * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2011-03-15 16:04:53]:
> >
> > Author: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
> > Date:   Thu Mar 10 14:45:25 2011 +0530
> >
> >    Move the paio_signal_handler to a generic location.
> >
> >    The paio subsystem uses the signal, SIGUSR2. So move
> >    the signal handler to a more generic place such that
> >    other subsystems like 9pfs can also use it.
> >
> >    TODO: I have moved the signal handler code to
> >    qemu-thread.c, which is NOT the right place. I need
> >    suggestions as to where is the right place to put it.
> 
> I think os-posix.c would be appropriate.  Please check how this
> affects Windows host and linux-user builds.
> 

Anthony's reply negates this point. I will remove the signalling code
and also check the behaviour of Windows host and linux-user builds.

> > @@ -356,6 +359,15 @@ static void *aio_thread(void *unused)
> >         idle_threads++;
> >         mutex_unlock(&lock);
> >
> > +        if (posix_aio_state) {
> 
> If we get here posix_aio_state must be non-NULL.  Please remove the check.
> 

Yes, will remove this.

> > +void sigusr2_signal_handler(int signum)
> 
> static void sigusr2_signal_handler(int signum)
> 

Thanks for noticing this.

> Stefan

Patch

diff --git a/posix-aio-compat.c b/posix-aio-compat.c
index fa5494d..df001d6 100644
--- a/posix-aio-compat.c
+++ b/posix-aio-compat.c
@@ -28,6 +28,7 @@ 
 #include "qemu-common.h"
 #include "trace.h"
 #include "block_int.h"
+#include "qemu-thread.h"
 
 #include "block/raw-posix-aio.h"
 
@@ -302,6 +303,8 @@  static ssize_t handle_aiocb_rw(struct qemu_paiocb *aiocb)
     return nbytes;
 }
 
+static PosixAioState *posix_aio_state;
+
 static void *aio_thread(void *unused)
 {
     pid_t pid;
@@ -356,6 +359,15 @@  static void *aio_thread(void *unused)
         idle_threads++;
         mutex_unlock(&lock);
 
+        if (posix_aio_state) {
+            char byte = 0;
+            ssize_t ret;
+
+            ret = write(posix_aio_state->wfd, &byte, sizeof(byte));
+            if (ret < 0 && errno != EAGAIN)
+                die("write()");
+        }
+
         if (kill(pid, aiocb->ev_signo)) die("kill failed");
     }
 
@@ -497,22 +509,6 @@  static int posix_aio_flush(void *opaque)
     return !!s->first_aio;
 }
 
-static PosixAioState *posix_aio_state;
-
-static void aio_signal_handler(int signum)
-{
-    if (posix_aio_state) {
-        char byte = 0;
-        ssize_t ret;
-
-        ret = write(posix_aio_state->wfd, &byte, sizeof(byte));
-        if (ret < 0 && errno != EAGAIN)
-            die("write()");
-    }
-
-    qemu_service_io();
-}
-
 static void paio_remove(struct qemu_paiocb *acb)
 {
     struct qemu_paiocb **pacb;
@@ -616,7 +612,6 @@  BlockDriverAIOCB *paio_ioctl(BlockDriverState *bs, int fd,
 
 int paio_init(void)
 {
-    struct sigaction act;
     PosixAioState *s;
     int fds[2];
     int ret;
@@ -626,11 +621,6 @@  int paio_init(void)
 
     s = qemu_malloc(sizeof(PosixAioState));
 
-    sigfillset(&act.sa_mask);
-    act.sa_flags = 0; /* do not restart syscalls to interrupt select() */
-    act.sa_handler = aio_signal_handler;
-    sigaction(SIGUSR2, &act, NULL);
-
     s->first_aio = NULL;
     if (qemu_pipe(fds) == -1) {
         fprintf(stderr, "failed to create pipe\n");
diff --git a/qemu-thread.c b/qemu-thread.c
index 2c521ab..bed1b60 100644
--- a/qemu-thread.c
+++ b/qemu-thread.c
@@ -149,3 +149,18 @@  void qemu_thread_exit(void *retval)
 {
     g_thread_exit(retval);
 }
+
+void sigusr2_signal_handler(int signum)
+{
+    qemu_service_io();
+}
+
+void register_sigusr2_signal_handler(void)
+{
+    struct sigaction act;
+
+    sigfillset(&act.sa_mask);
+    act.sa_flags = 0; /* do not restart syscalls to interrupt select() */
+    act.sa_handler = sigusr2_signal_handler;
+    sigaction(SIGUSR2, &act, NULL);
+}
diff --git a/qemu-thread.h b/qemu-thread.h
index dc22a60..0f1cbe8 100644
--- a/qemu-thread.h
+++ b/qemu-thread.h
@@ -41,5 +41,7 @@  void qemu_thread_signal(QemuThread *thread, int sig);
 void qemu_thread_self(QemuThread *thread);
 int qemu_thread_equal(QemuThread *thread1, QemuThread *thread2);
 void qemu_thread_exit(void *retval);
+void sigusr2_signal_handler(int signum);
+void register_sigusr2_signal_handler(void);
 
 #endif
diff --git a/vl.c b/vl.c
index 3225b1d..a8dc4fc 100644
--- a/vl.c
+++ b/vl.c
@@ -148,6 +148,7 @@  int main(int argc, char **argv)
 #include "qemu-config.h"
 #include "qemu-objects.h"
 #include "qemu-options.h"
+#include "qemu-thread.h"
 #ifdef CONFIG_VIRTFS
 #include "fsdev/qemu-fsdev.h"
 #endif
@@ -3003,6 +3004,8 @@  int main(int argc, char **argv, char **envp)
         }
     }
 
+    register_sigusr2_signal_handler();
+
     if (qemu_opts_foreach(qemu_find_opts("mon"), mon_init_func, NULL, 1) != 0) {
         exit(1);
     }