[PATCH] Add VM info to improve error log message for qemu monitor

[Daniel P. Berrangé]

On Tue, Dec 07, 2021 at 05:34:00AM -0800, Rohit Kumar wrote:
> This patch is to determine the VM which had IO or socket hangup error.
> 
> Signed-off-by: Rohit Kumar <rohit.kumar3 at nutanix.com>
> ---
>  src/qemu/qemu_monitor.c | 46 +++++++++++++++++++++++++----------------
>  1 file changed, 28 insertions(+), 18 deletions(-)
> 
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index 75e0e4ed92..d36db280d9 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -530,13 +530,19 @@ qemuMonitorIO(GSocket *socket G_GNUC_UNUSED,
>      qemuMonitor *mon = opaque;
>      bool error = false;
>      bool hangup = false;
> +    virDomainObj *vm = mon->vm;
> +    g_autofree char *vmName = NULL;
> +
> +    if (vm != NULL && vm->def != NULL) {
> +        vmName = g_strdup(vm->def->name);
> +    }

This looks a little questionable.

Although we hold a reference on 'vm', this code doesn't do anything
to protect its access of 'vm->def'. If we were protected when accesing
vm->def, then we wouldn't need to strdup it anyway.


>  
>      virObjectRef(mon);
>  
>      /* lock access to the monitor and protect fd */
>      virObjectLock(mon);
>  #if DEBUG_IO
> -    VIR_DEBUG("Monitor %p I/O on socket %p cond %d", mon, socket, cond);
> +    VIR_DEBUG("Monitor %p I/O on socket %p cond %d vm=%p name=%s", mon, socket, cond, vm, NULLSTR(vmName));
>  #endif
>      if (mon->fd == -1 || !mon->watch) {
>          virObjectUnlock(mon);
> @@ -583,8 +589,8 @@ qemuMonitorIO(GSocket *socket G_GNUC_UNUSED,
>  
>          if (!error && !mon->goteof &&
>              cond & G_IO_ERR) {
> -            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> -                           _("Invalid file descriptor while waiting for monitor"));
> +            virReportError(VIR_ERR_INTERNAL_ERROR,
> +                           _("Invalid file descriptor while waiting for monitor vm_name=%s"), NULLSTR(vmName));
>              mon->goteof = true;
>          }
>      }
> @@ -609,13 +615,13 @@ qemuMonitorIO(GSocket *socket G_GNUC_UNUSED,
>              virResetLastError();
>          } else {
>              if (virGetLastErrorCode() == VIR_ERR_OK && !mon->goteof)
> -                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> -                               _("Error while processing monitor IO"));
> +                virReportError(VIR_ERR_INTERNAL_ERROR,
> +                               _("Error while processing monitor IO vm_name=%s"), NULLSTR(vmName));
>              virCopyLastError(&mon->lastError);
>              virResetLastError();
>          }
>  
> -        VIR_DEBUG("Error on monitor %s", NULLSTR(mon->lastError.message));
> +        VIR_DEBUG("Error on monitor %s vm=%p name=%s", NULLSTR(mon->lastError.message), vm, NULLSTR(vmName));
>          /* If IO process resulted in an error & we have a message,
>           * then wakeup that waiter */
>          if (mon->msg && !mon->msg->finished) {
> @@ -631,22 +637,20 @@ qemuMonitorIO(GSocket *socket G_GNUC_UNUSED,
>       * will try to acquire the virDomainObj *mutex next */
>      if (mon->goteof) {
>          qemuMonitorEofNotifyCallback eofNotify = mon->cb->eofNotify;
> -        virDomainObj *vm = mon->vm;
>  
>          /* Make sure anyone waiting wakes up now */
>          virCondSignal(&mon->notify);
>          virObjectUnlock(mon);
> -        VIR_DEBUG("Triggering EOF callback");
> +        VIR_DEBUG("Triggering EOF callback vm=%p name=%s", vm, NULLSTR(vmName));
>          (eofNotify)(mon, vm, mon->callbackOpaque);
>          virObjectUnref(mon);
>      } else if (error) {
>          qemuMonitorErrorNotifyCallback errorNotify = mon->cb->errorNotify;
> -        virDomainObj *vm = mon->vm;
>  
>          /* Make sure anyone waiting wakes up now */
>          virCondSignal(&mon->notify);
>          virObjectUnlock(mon);
> -        VIR_DEBUG("Triggering error callback");
> +        VIR_DEBUG("Triggering error callback vm=%p name=%s", vm, NULLSTR(vmName));
>          (errorNotify)(mon, vm, mon->callbackOpaque);
>          virObjectUnref(mon);
>      } else {
> @@ -932,17 +936,23 @@ qemuMonitorSend(qemuMonitor *mon,
>                  qemuMonitorMessage *msg)
>  {
>      int ret = -1;
> +    virDomainObj *vm = mon->vm;
> +    g_autofree char *vmName = NULL;
> +
> +    if (vm != NULL && vm->def != NULL) {
> +        vmName = g_strdup(vm->def->name);
> +    }
>  
>      /* Check whether qemu quit unexpectedly */
>      if (mon->lastError.code != VIR_ERR_OK) {
> -        VIR_DEBUG("Attempt to send command while error is set %s",
> -                  NULLSTR(mon->lastError.message));
> +        VIR_DEBUG("Attempt to send command while error is set %s vm=%p name=%s",
> +                  NULLSTR(mon->lastError.message), vm, NULLSTR(vmName));
>          virSetError(&mon->lastError);
>          return -1;
>      }
>      if (mon->goteof) {
> -        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> -                       _("End of file from qemu monitor"));
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("End of file from qemu monitor vm_name=%s"), NULLSTR(vmName));
>          return -1;
>      }
>  
> @@ -955,15 +965,15 @@ qemuMonitorSend(qemuMonitor *mon,
>  
>      while (!mon->msg->finished) {
>          if (virCondWait(&mon->notify, &mon->parent.lock) < 0) {
> -            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> -                           _("Unable to wait on monitor condition"));
> +            virReportError(VIR_ERR_INTERNAL_ERROR,
> +                           _("Unable to wait on monitor condition vm_name=%s"), NULLSTR(vmName));
>              goto cleanup;
>          }
>      }
>  
>      if (mon->lastError.code != VIR_ERR_OK) {
> -        VIR_DEBUG("Send command resulted in error %s",
> -                  NULLSTR(mon->lastError.message));
> +        VIR_DEBUG("Send command resulted in error %s vm=%p name=%s",
> +                  NULLSTR(mon->lastError.message), vm, NULLSTR(vmName));
>          virSetError(&mon->lastError);
>          goto cleanup;
>      }
> -- 
> 2.25.1
> 

Regards,
Daniel
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