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Re: [libvirt] [PATCH] Move most of qemuProcessKill into virProcessKillPainfully



On 09/26/2012 10:44 AM, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange redhat com>
>
> In the cgroups APIs we have a virCgroupKillPainfully function
> which does the loop sending SIGTERM, then SIGKILL and waiting
> for the process to exit. There is similar functionality for
> simple processes in qemuProcessKill, but it is tangled with
> the QEMU code. Untangle it to provide a virProcessKillPainfuly
> function
> ---
>  src/libvirt_private.syms |  1 +
>  src/qemu/qemu_driver.c   |  8 ++---
>  src/qemu/qemu_process.c  | 79 ++++++++----------------------------------------
>  src/util/virprocess.c    | 57 ++++++++++++++++++++++++++++++++++
>  src/util/virprocess.h    |  2 ++
>  5 files changed, 76 insertions(+), 71 deletions(-)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 4635a4d..dab607a 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -1708,6 +1708,7 @@ virPidFileDeletePath;
>  # virprocess.h
>  virProcessAbort;
>  virProcessKill;
> +virProcessKillPainfully;
>  virProcessTranslateStatus;
>  virProcessWait;
>  
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 7ac53ac..22fef7a 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -2006,13 +2006,11 @@ qemuDomainDestroyFlags(virDomainPtr dom,
>       * it now means the job will be released
>       */
>      if (flags & VIR_DOMAIN_DESTROY_GRACEFUL) {
> -        if (qemuProcessKill(driver, vm, 0) < 0) {
> -            virReportError(VIR_ERR_OPERATION_FAILED, "%s",
> -                           _("failed to kill qemu process with SIGTERM"));
> +        if (qemuProcessKill(driver, vm, 0) < 0)
>              goto cleanup;
> -        }
>      } else {
> -        ignore_value(qemuProcessKill(driver, vm, VIR_QEMU_PROCESS_KILL_FORCE));
> +        if (qemuProcessKill(driver, vm, VIR_QEMU_PROCESS_KILL_FORCE) < 0)
> +            goto cleanup;
>      }
>  
>      /* We need to prevent monitor EOF callback from doing our work (and sending
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 3cd30af..70b72af 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -3877,9 +3877,7 @@ int
>  qemuProcessKill(struct qemud_driver *driver,
>                  virDomainObjPtr vm, unsigned int flags)
>  {
> -    int i, ret = -1;
> -    const char *signame = "TERM";
> -    bool driver_unlocked = false;
> +    int ret;
>  
>      VIR_DEBUG("vm=%s pid=%d flags=%x",
>                vm->def->name, vm->pid, flags);
> @@ -3891,78 +3889,27 @@ qemuProcessKill(struct qemud_driver *driver,
>          }
>      }
>  
> -    /* This loop sends SIGTERM (or SIGKILL if flags has
> -     * VIR_QEMU_PROCESS_KILL_FORCE and VIR_QEMU_PROCESS_KILL_NOWAIT),
> -     * then waits a few iterations (10 seconds) to see if it dies. If
> -     * the qemu process still hasn't exited, and
> -     * VIR_QEMU_PROCESS_KILL_FORCE is requested, a SIGKILL will then
> -     * be sent, and qemuProcessKill will wait up to 5 seconds more for
> -     * the process to exit before returning.  Note that the FORCE mode
> -     * could result in lost data in the guest, so it should only be
> -     * used if the guest is hung and can't be destroyed in any other
> -     * manner.
> -     */
> -    for (i = 0 ; i < 75; i++) {
> -        int signum;
> -        if (i == 0) {
> -            if ((flags & VIR_QEMU_PROCESS_KILL_FORCE) &&
> -                (flags & VIR_QEMU_PROCESS_KILL_NOWAIT)) {
> -                signum = SIGKILL; /* kill it immediately */
> -                signame="KILL";
> -            } else {
> -                signum = SIGTERM; /* kindly suggest it should exit */
> -            }
> -        } else if ((i == 50) & (flags & VIR_QEMU_PROCESS_KILL_FORCE)) {
> -            VIR_WARN("Timed out waiting after SIG%s to process %d, "
> -                     "sending SIGKILL", signame, vm->pid);
> -            signum = SIGKILL; /* kill it after a grace period */
> -            signame="KILL";
> -        } else {
> -            signum = 0; /* Just check for existence */
> -        }
> -
> -        if (virProcessKill(vm->pid, signum) < 0) {
> -            if (errno != ESRCH) {
> -                char ebuf[1024];
> -                VIR_WARN("Failed to terminate process %d with SIG%s: %s",
> -                         vm->pid, signame,
> -                         virStrerror(errno, ebuf, sizeof(ebuf)));
> -                goto cleanup;
> -            }
> -            ret = 0;
> -            goto cleanup; /* process is dead */
> -        }
> +    if ((flags & VIR_QEMU_PROCESS_KILL_NOWAIT)) {
> +        virProcessKill(vm->pid,
> +                       (flags & VIR_QEMU_PROCESS_KILL_FORCE) ?
> +                       SIGKILL : SIGTERM);
> +        return 0;
> +    }
>  
> -        if (i == 0 && (flags & VIR_QEMU_PROCESS_KILL_NOWAIT)) {
> -            ret = 0;
> -            goto cleanup;
> -        }
> +    if (driver)
> +        qemuDriverUnlock(driver);
>  
> -        if (driver && !driver_unlocked) {
> -            /* THREADS.txt says we can't hold the driver lock while sleeping */
> -            qemuDriverUnlock(driver);
> -            driver_unlocked = true;
> -        }
> +    ret = virProcessKillPainfully(vm->pid,
> +                                  !!(flags & VIR_QEMU_PROCESS_KILL_FORCE));
>  
> -        usleep(200 * 1000);
> -    }
> -    VIR_WARN("Timed out waiting after SIG%s to process %d", signame, vm->pid);
> -cleanup:
> -    if (driver_unlocked) {
> -        /* We had unlocked the driver, so re-lock it. THREADS.txt says
> -         * we can't have the domain locked when locking the driver, so
> -         * we must first unlock the domain. BUT, before we can unlock
> -         * the domain, we need to add a ref to it in case there aren't
> -         * any active jobs (analysis of all callers didn't reveal such
> -         * a case, but there are too many to maintain certainty, so we
> -         * will do this as a precaution).
> -         */
> +    if (driver) {
>          virObjectRef(vm);
>          virDomainObjUnlock(vm);
>          qemuDriverLock(driver);
>          virDomainObjLock(vm);
>          virObjectUnref(vm);
>      }
> +
>      return ret;
>  }
>  
> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
> index 958f5f7..c70aa58 100644
> --- a/src/util/virprocess.c
> +++ b/src/util/virprocess.c
> @@ -235,3 +235,60 @@ int virProcessKill(pid_t pid, int sig)
>      return kill(pid, sig);
>  #endif
>  }
> +
> +
> +/*
> + * Try to kill the process and verify it has exited
> + *
> + * Returns 0 if it was killed gracefully, 1 if it
> + * was killed forcably, -1 if it is still alive,
> + * or another error occurred.
> + */
> +int
> +virProcessKillPainfully(pid_t pid, bool force)
> +{
> +    int i, ret = -1;
> +    const char *signame = "TERM";
> +
> +    VIR_DEBUG("vpid=%d force=%d", pid, force);
> +
> +    /* This loop sends SIGTERM, then waits a few iterations (10 seconds)
> +     * to see if it dies. If the process still hasn't exited, and
> +     * @force is requested, a SIGKILL will be sent, and this will
> +     * wait upto 5 seconds more for the process to exit before
> +     * returning.
> +     *
> +     * Note that setting @force could result in dataloss for the process.
> +     */
> +    for (i = 0 ; i < 75; i++) {
> +        int signum;
> +        if (i == 0) {
> +            signum = SIGTERM; /* kindly suggest it should exit */
> +        } else if ((i == 50) & force) {
> +            VIR_DEBUG("Timed out waiting after SIGTERM to process %d, "
> +                      "sending SIGKILL", pid);
> +            signum = SIGKILL; /* kill it after a grace period */
> +            signame = "KILL";
> +        } else {
> +            signum = 0; /* Just check for existence */
> +        }

Hmm. I just added a similar kill loop in bridge_driver.c. The main
difference is that it doesn't wait as long (not for any particular
reason, though).

I guess I should change it to use this. (I actually considered making a
utility function at the time, but it was too close to release, so I
didn't want to touch other drivers...)


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