* [LTP] [PATCH v2] syscalls/tgkill03: wait for defunct tid to get detached
@ 2019-06-17 7:33 Jan Stancek
2019-06-17 8:05 ` Li Wang
2019-06-17 9:18 ` Sumit Garg
0 siblings, 2 replies; 4+ messages in thread
From: Jan Stancek @ 2019-06-17 7:33 UTC (permalink / raw)
To: ltp
Case where defunct tid is used has been observed to sporadically fail:
tgkill03.c:96: FAIL: Defunct tid should have failed with ESRCH: SUCCESS
glibc __pthread_timedjoin_ex() waits for CLONE_CHILD_CLEARTID to clear tid,
and then resumes. Kernel clears it (glibc pd->tid) at:
do_exit
exit_mm
mm_release
put_user(0, tsk->clear_child_tid);
but kernel tid is still valid, presumably until:
release_task
__exit_signal
__unhash_process
detach_pid
To avoid race wait until /proc/<pid>/task/<tid> disappears.
Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
testcases/kernel/syscalls/tgkill/tgkill03.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
Changes in v2:
- use helper func suggested by Li (with higher timeout)
- not tested, trying to get s390x to confirm
diff --git a/testcases/kernel/syscalls/tgkill/tgkill03.c b/testcases/kernel/syscalls/tgkill/tgkill03.c
index f5bbdc5a8d4e..ce046f576b5f 100644
--- a/testcases/kernel/syscalls/tgkill/tgkill03.c
+++ b/testcases/kernel/syscalls/tgkill/tgkill03.c
@@ -7,6 +7,7 @@
#include <pthread.h>
#include <pwd.h>
+#include <stdio.h>
#include <sys/types.h>
#include "tst_safe_pthread.h"
@@ -42,6 +43,7 @@ static void setup(void)
{
sigset_t sigusr1;
pthread_t defunct_thread;
+ char defunct_tid_path[PATH_MAX];
sigemptyset(&sigusr1);
sigaddset(&sigusr1, SIGUSR1);
@@ -55,8 +57,9 @@ static void setup(void)
TST_CHECKPOINT_WAIT(0);
SAFE_PTHREAD_CREATE(&defunct_thread, NULL, defunct_thread_func, NULL);
-
SAFE_PTHREAD_JOIN(defunct_thread, NULL);
+ sprintf(defunct_tid_path, "/proc/%d/task/%d", getpid(), defunct_tid);
+ TST_RETRY_FN_EXP_BACKOFF(access(defunct_tid_path, R_OK), -1, 15);
}
static void cleanup(void)
@@ -108,4 +111,5 @@ static struct tst_test test = {
.setup = setup,
.cleanup = cleanup,
.test = run,
+ .timeout = 15,
};
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [LTP] [PATCH v2] syscalls/tgkill03: wait for defunct tid to get detached
2019-06-17 7:33 [LTP] [PATCH v2] syscalls/tgkill03: wait for defunct tid to get detached Jan Stancek
@ 2019-06-17 8:05 ` Li Wang
2019-06-17 11:34 ` Jan Stancek
2019-06-17 9:18 ` Sumit Garg
1 sibling, 1 reply; 4+ messages in thread
From: Li Wang @ 2019-06-17 8:05 UTC (permalink / raw)
To: ltp
On Mon, Jun 17, 2019 at 3:34 PM Jan Stancek <jstancek@redhat.com> wrote:
> Case where defunct tid is used has been observed to sporadically fail:
> tgkill03.c:96: FAIL: Defunct tid should have failed with ESRCH: SUCCESS
>
> glibc __pthread_timedjoin_ex() waits for CLONE_CHILD_CLEARTID to clear tid,
> and then resumes. Kernel clears it (glibc pd->tid) at:
> do_exit
> exit_mm
> mm_release
> put_user(0, tsk->clear_child_tid);
>
> but kernel tid is still valid, presumably until:
> release_task
> __exit_signal
> __unhash_process
> detach_pid
>
> To avoid race wait until /proc/<pid>/task/<tid> disappears.
>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
> testcases/kernel/syscalls/tgkill/tgkill03.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> Changes in v2:
> - use helper func suggested by Li (with higher timeout)
> - not tested, trying to get s390x to confirm
>
> diff --git a/testcases/kernel/syscalls/tgkill/tgkill03.c
> b/testcases/kernel/syscalls/tgkill/tgkill03.c
> index f5bbdc5a8d4e..ce046f576b5f 100644
> --- a/testcases/kernel/syscalls/tgkill/tgkill03.c
> +++ b/testcases/kernel/syscalls/tgkill/tgkill03.c
> @@ -7,6 +7,7 @@
>
> #include <pthread.h>
> #include <pwd.h>
> +#include <stdio.h>
> #include <sys/types.h>
>
> #include "tst_safe_pthread.h"
> @@ -42,6 +43,7 @@ static void setup(void)
> {
> sigset_t sigusr1;
> pthread_t defunct_thread;
> + char defunct_tid_path[PATH_MAX];
>
> sigemptyset(&sigusr1);
> sigaddset(&sigusr1, SIGUSR1);
> @@ -55,8 +57,9 @@ static void setup(void)
> TST_CHECKPOINT_WAIT(0);
>
> SAFE_PTHREAD_CREATE(&defunct_thread, NULL, defunct_thread_func,
> NULL);
> -
> SAFE_PTHREAD_JOIN(defunct_thread, NULL);
> + sprintf(defunct_tid_path, "/proc/%d/task/%d", getpid(),
> defunct_tid);
> + TST_RETRY_FN_EXP_BACKOFF(access(defunct_tid_path, R_OK), -1, 15);
> }
>
> static void cleanup(void)
> @@ -108,4 +111,5 @@ static struct tst_test test = {
> .setup = setup,
> .cleanup = cleanup,
> .test = run,
> + .timeout = 15,
>
I'd like to give a little bit more time here which larger than the
exponential backoff macro time.
Anyway, v2 looks good.
Reviewed-by: Li Wang <liwang@redhat.com>
--
Regards,
Li Wang
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^ permalink raw reply [flat|nested] 4+ messages in thread* [LTP] [PATCH v2] syscalls/tgkill03: wait for defunct tid to get detached
2019-06-17 8:05 ` Li Wang
@ 2019-06-17 11:34 ` Jan Stancek
0 siblings, 0 replies; 4+ messages in thread
From: Jan Stancek @ 2019-06-17 11:34 UTC (permalink / raw)
To: ltp
----- Original Message -----
> On Mon, Jun 17, 2019 at 3:34 PM Jan Stancek <jstancek@redhat.com> wrote:
>
> > Case where defunct tid is used has been observed to sporadically fail:
> > tgkill03.c:96: FAIL: Defunct tid should have failed with ESRCH: SUCCESS
> >
> > glibc __pthread_timedjoin_ex() waits for CLONE_CHILD_CLEARTID to clear tid,
> > and then resumes. Kernel clears it (glibc pd->tid) at:
> > do_exit
> > exit_mm
> > mm_release
> > put_user(0, tsk->clear_child_tid);
> >
> > but kernel tid is still valid, presumably until:
> > release_task
> > __exit_signal
> > __unhash_process
> > detach_pid
> >
> > To avoid race wait until /proc/<pid>/task/<tid> disappears.
> >
> > Signed-off-by: Jan Stancek <jstancek@redhat.com>
> > ---
> > testcases/kernel/syscalls/tgkill/tgkill03.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > Changes in v2:
> > - use helper func suggested by Li (with higher timeout)
> > - not tested, trying to get s390x to confirm
> >
> > diff --git a/testcases/kernel/syscalls/tgkill/tgkill03.c
> > b/testcases/kernel/syscalls/tgkill/tgkill03.c
> > index f5bbdc5a8d4e..ce046f576b5f 100644
> > --- a/testcases/kernel/syscalls/tgkill/tgkill03.c
> > +++ b/testcases/kernel/syscalls/tgkill/tgkill03.c
> > @@ -7,6 +7,7 @@
> >
> > #include <pthread.h>
> > #include <pwd.h>
> > +#include <stdio.h>
> > #include <sys/types.h>
> >
> > #include "tst_safe_pthread.h"
> > @@ -42,6 +43,7 @@ static void setup(void)
> > {
> > sigset_t sigusr1;
> > pthread_t defunct_thread;
> > + char defunct_tid_path[PATH_MAX];
> >
> > sigemptyset(&sigusr1);
> > sigaddset(&sigusr1, SIGUSR1);
> > @@ -55,8 +57,9 @@ static void setup(void)
> > TST_CHECKPOINT_WAIT(0);
> >
> > SAFE_PTHREAD_CREATE(&defunct_thread, NULL, defunct_thread_func,
> > NULL);
> > -
> > SAFE_PTHREAD_JOIN(defunct_thread, NULL);
> > + sprintf(defunct_tid_path, "/proc/%d/task/%d", getpid(),
> > defunct_tid);
> > + TST_RETRY_FN_EXP_BACKOFF(access(defunct_tid_path, R_OK), -1, 15);
> > }
> >
> > static void cleanup(void)
> > @@ -108,4 +111,5 @@ static struct tst_test test = {
> > .setup = setup,
> > .cleanup = cleanup,
> > .test = run,
> > + .timeout = 15,
> >
>
> I'd like to give a little bit more time here which larger than the
> exponential backoff macro time.
I bumped it to 20 and pushed.
Thanks,
Jan
^ permalink raw reply [flat|nested] 4+ messages in thread
* [LTP] [PATCH v2] syscalls/tgkill03: wait for defunct tid to get detached
2019-06-17 7:33 [LTP] [PATCH v2] syscalls/tgkill03: wait for defunct tid to get detached Jan Stancek
2019-06-17 8:05 ` Li Wang
@ 2019-06-17 9:18 ` Sumit Garg
1 sibling, 0 replies; 4+ messages in thread
From: Sumit Garg @ 2019-06-17 9:18 UTC (permalink / raw)
To: ltp
On Mon, 17 Jun 2019 at 13:04, Jan Stancek <jstancek@redhat.com> wrote:
>
> Case where defunct tid is used has been observed to sporadically fail:
> tgkill03.c:96: FAIL: Defunct tid should have failed with ESRCH: SUCCESS
>
> glibc __pthread_timedjoin_ex() waits for CLONE_CHILD_CLEARTID to clear tid,
> and then resumes. Kernel clears it (glibc pd->tid) at:
> do_exit
> exit_mm
> mm_release
> put_user(0, tsk->clear_child_tid);
>
> but kernel tid is still valid, presumably until:
> release_task
> __exit_signal
> __unhash_process
> detach_pid
>
> To avoid race wait until /proc/<pid>/task/<tid> disappears.
>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
Thanks for this fix.
Acked-by: Sumit Garg <sumit.garg@linaro.org>
-Sumit
> ---
> testcases/kernel/syscalls/tgkill/tgkill03.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> Changes in v2:
> - use helper func suggested by Li (with higher timeout)
> - not tested, trying to get s390x to confirm
>
> diff --git a/testcases/kernel/syscalls/tgkill/tgkill03.c b/testcases/kernel/syscalls/tgkill/tgkill03.c
> index f5bbdc5a8d4e..ce046f576b5f 100644
> --- a/testcases/kernel/syscalls/tgkill/tgkill03.c
> +++ b/testcases/kernel/syscalls/tgkill/tgkill03.c
> @@ -7,6 +7,7 @@
>
> #include <pthread.h>
> #include <pwd.h>
> +#include <stdio.h>
> #include <sys/types.h>
>
> #include "tst_safe_pthread.h"
> @@ -42,6 +43,7 @@ static void setup(void)
> {
> sigset_t sigusr1;
> pthread_t defunct_thread;
> + char defunct_tid_path[PATH_MAX];
>
> sigemptyset(&sigusr1);
> sigaddset(&sigusr1, SIGUSR1);
> @@ -55,8 +57,9 @@ static void setup(void)
> TST_CHECKPOINT_WAIT(0);
>
> SAFE_PTHREAD_CREATE(&defunct_thread, NULL, defunct_thread_func, NULL);
> -
> SAFE_PTHREAD_JOIN(defunct_thread, NULL);
> + sprintf(defunct_tid_path, "/proc/%d/task/%d", getpid(), defunct_tid);
> + TST_RETRY_FN_EXP_BACKOFF(access(defunct_tid_path, R_OK), -1, 15);
> }
>
> static void cleanup(void)
> @@ -108,4 +111,5 @@ static struct tst_test test = {
> .setup = setup,
> .cleanup = cleanup,
> .test = run,
> + .timeout = 15,
> };
> --
> 1.8.3.1
>
>
> --
> Mailing list info: https://lists.linux.it/listinfo/ltp
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-06-17 7:33 [LTP] [PATCH v2] syscalls/tgkill03: wait for defunct tid to get detached Jan Stancek
2019-06-17 8:05 ` Li Wang
2019-06-17 11:34 ` Jan Stancek
2019-06-17 9:18 ` Sumit Garg
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