[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Alexey Kodanev]

musl doesn't return ESRCH for pthread_kill() if thread id is not found.

POSIX only recommends to return ESRCH, and also says that pthread_kill()
produces undefined behavior if tid lifetime has ended [1].

[1]: https://man7.org/linux/man-pages/man3/pthread_kill.3.html

Signed-off-by: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
---
 testcases/kernel/crypto/af_alg02.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/testcases/kernel/crypto/af_alg02.c b/testcases/kernel/crypto/af_alg02.c
index 31d30777c..0f5793c16 100644
--- a/testcases/kernel/crypto/af_alg02.c
+++ b/testcases/kernel/crypto/af_alg02.c
@@ -60,7 +60,7 @@ static void run(void)
 
 	TST_CHECKPOINT_WAIT(0);
 
-	while (pthread_kill(thr, 0) != ESRCH) {
+	while (pthread_tryjoin_np(thr, NULL) == EBUSY) {
 		if (tst_timeout_remaining() <= 10) {
 			pthread_cancel(thr);
 			tst_brk(TBROK,
-- 
2.25.1

[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Li Wang]

Hi Alexey,

On Thu, Jul 15, 2021 at 6:29 PM Alexey Kodanev <aleksei.kodanev@bell-sw.com>
wrote:

> musl doesn't return ESRCH for pthread_kill() if thread id is not found.
>
> POSIX only recommends to return ESRCH, and also says that pthread_kill()
> produces undefined behavior if tid lifetime has ended [1].
>
> [1]: https://man7.org/linux/man-pages/man3/pthread_kill.3.html
>
> Signed-off-by: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
> ---
>  testcases/kernel/crypto/af_alg02.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/testcases/kernel/crypto/af_alg02.c
> b/testcases/kernel/crypto/af_alg02.c
> index 31d30777c..0f5793c16 100644
> --- a/testcases/kernel/crypto/af_alg02.c
> +++ b/testcases/kernel/crypto/af_alg02.c
> @@ -60,7 +60,7 @@ static void run(void)
>
>         TST_CHECKPOINT_WAIT(0);
>
> -       while (pthread_kill(thr, 0) != ESRCH) {
> +       while (pthread_tryjoin_np(thr, NULL) == EBUSY) {
>

I'm not sure if safe enough to use because it is nonstandard GNU extensions
and the "_np" means nonportable.

Maybe another workaround is to define a volatile flag 'thread_complete',
initialize it to '0' when thread_B starts and reset to '1' while exit, and
just
do a value check in the while loop of thread_A should acquire thread_B
status.
Is this way a bit better?

-- 
Regards,
Li Wang
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[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Petr Vorel]

> Hi Alexey,

> On Thu, Jul 15, 2021 at 6:29 PM Alexey Kodanev <aleksei.kodanev@bell-sw.com>
> wrote:

> > musl doesn't return ESRCH for pthread_kill() if thread id is not found.
Maybe ask on MUSL mailing list?

> > POSIX only recommends to return ESRCH, and also says that pthread_kill()
> > produces undefined behavior if tid lifetime has ended [1].

> > [1]: https://man7.org/linux/man-pages/man3/pthread_kill.3.html

> > Signed-off-by: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
> > ---
> >  testcases/kernel/crypto/af_alg02.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)

> > diff --git a/testcases/kernel/crypto/af_alg02.c
> > b/testcases/kernel/crypto/af_alg02.c
> > index 31d30777c..0f5793c16 100644
> > --- a/testcases/kernel/crypto/af_alg02.c
> > +++ b/testcases/kernel/crypto/af_alg02.c
> > @@ -60,7 +60,7 @@ static void run(void)

> >         TST_CHECKPOINT_WAIT(0);

> > -       while (pthread_kill(thr, 0) != ESRCH) {
> > +       while (pthread_tryjoin_np(thr, NULL) == EBUSY) {


> I'm not sure if safe enough to use because it is nonstandard GNU extensions
> and the "_np" means nonportable.
Others please double check, but pthread_tryjoin_np() seems to be in uclibc-ng
and musl (+ of course in glibc). It's only missing in bionic (it looks like
people would like to have it [1]).

> Maybe another workaround is to define a volatile flag 'thread_complete',
> initialize it to '0' when thread_B starts and reset to '1' while exit, and
> just
> do a value check in the while loop of thread_A should acquire thread_B
> status.
> Is this way a bit better?
Sounds as reasonable workaround for me.

Kind regards,
Petr

[1] https://github.com/kito-cheng/android-checkpoint/blob/master/bionic/0003-bionic-Implement-pthread_tryjoin_np.patch

[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Alexey Kodanev]

Hi Li,
On 16.07.2021 10:06, Li Wang wrote:
> Hi Alexey,
> 
> On Thu, Jul 15, 2021 at 6:29 PM Alexey Kodanev <aleksei.kodanev@bell-sw.com <mailto:aleksei.kodanev@bell-sw.com>> wrote:
> 
>     musl doesn't return ESRCH for pthread_kill() if thread id is not found.
> 
>     POSIX only recommends to return ESRCH, and also says that pthread_kill()
>     produces undefined behavior if tid lifetime has ended [1].
> 
>     [1]: https://man7.org/linux/man-pages/man3/pthread_kill.3.html <https://man7.org/linux/man-pages/man3/pthread_kill.3.html>
> 
>     Signed-off-by: Alexey Kodanev <aleksei.kodanev@bell-sw.com <mailto:aleksei.kodanev@bell-sw.com>>
>     ---
>     ?testcases/kernel/crypto/af_alg02.c | 2 +-
>     ?1 file changed, 1 insertion(+), 1 deletion(-)
> 
>     diff --git a/testcases/kernel/crypto/af_alg02.c b/testcases/kernel/crypto/af_alg02.c
>     index 31d30777c..0f5793c16 100644
>     --- a/testcases/kernel/crypto/af_alg02.c
>     +++ b/testcases/kernel/crypto/af_alg02.c
>     @@ -60,7 +60,7 @@ static void run(void)
> 
>     ? ? ? ? TST_CHECKPOINT_WAIT(0);
> 
>     -? ? ? ?while (pthread_kill(thr, 0) != ESRCH) {
>     +? ? ? ?while (pthread_tryjoin_np(thr, NULL) == EBUSY) {
> 
> 
> I'm not sure ifsafeenough to use because it is nonstandard GNU extensions
> and the "_np" means nonportable.
> 
> Maybe another workaround is to define a volatile?flag 'thread_complete',?
> initialize it to '0' when thread_B starts and reset to '1' while exit, and just
> do a value check in the while loop of thread_A should acquire?thread_B status.
> Is this way a bit better? 

OK, why not, so something like this:

diff --git a/testcases/kernel/crypto/af_alg02.c b/testcases/kernel/crypto/af_alg02.c
index 0f5793c16..1fe0f3bf0 100644
--- a/testcases/kernel/crypto/af_alg02.c
+++ b/testcases/kernel/crypto/af_alg02.c
@@ -18,11 +18,13 @@
 #include "tst_test.h"
 #include "tst_af_alg.h"
 #include "tst_safe_pthread.h"
+#include "tst_atomic.h"
 #include <pthread.h>
 #include <errno.h>

 #define SALSA20_IV_SIZE       8
 #define SALSA20_MIN_KEY_SIZE  16
+static int completed;

 static void *verify_encrypt(void *arg)
 {
@@ -48,6 +50,8 @@ static void *verify_encrypt(void *arg)
                tst_res(TPASS, "Successfully \"encrypted\" an empty message");
        else
                tst_res(TFAIL, "read() didn't return 0");
+
+       tst_atomic_store(1, &completed);
        return arg;
 }

@@ -60,7 +64,7 @@ static void run(void)

        TST_CHECKPOINT_WAIT(0);

-       while (pthread_tryjoin_np(thr, NULL) == EBUSY) {
+       while (!tst_atomic_load(&completed)) {
                if (tst_timeout_remaining() <= 10) {
                        pthread_cancel(thr);
                        tst_brk(TBROK,

[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Alexey Kodanev]

Hi Petr,
On 16.07.2021 12:51, Petr Vorel wrote:
>> Hi Alexey,
> 
>> On Thu, Jul 15, 2021 at 6:29 PM Alexey Kodanev <aleksei.kodanev@bell-sw.com>
>> wrote:
> 
>>> musl doesn't return ESRCH for pthread_kill() if thread id is not found.
> Maybe ask on MUSL mailing list?

It's not a musl issue, but I was going to send a few improvements (including
this) when time permits.

> 
>>> POSIX only recommends to return ESRCH, and also says that pthread_kill()
>>> produces undefined behavior if tid lifetime has ended [1].
> 
>>> [1]: https://man7.org/linux/man-pages/man3/pthread_kill.3.html
> 
>>> Signed-off-by: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
>>> ---
>>>  testcases/kernel/crypto/af_alg02.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
>>> diff --git a/testcases/kernel/crypto/af_alg02.c
>>> b/testcases/kernel/crypto/af_alg02.c
>>> index 31d30777c..0f5793c16 100644
>>> --- a/testcases/kernel/crypto/af_alg02.c
>>> +++ b/testcases/kernel/crypto/af_alg02.c
>>> @@ -60,7 +60,7 @@ static void run(void)
> 
>>>         TST_CHECKPOINT_WAIT(0);
> 
>>> -       while (pthread_kill(thr, 0) != ESRCH) {
>>> +       while (pthread_tryjoin_np(thr, NULL) == EBUSY) {
> 
> 
>> I'm not sure if safe enough to use because it is nonstandard GNU extensions
>> and the "_np" means nonportable.
> Others please double check, but pthread_tryjoin_np() seems to be in uclibc-ng
> and musl (+ of course in glibc). It's only missing in bionic (it looks like
> people would like to have it [1]).
> 

Yeah, I think it's quite useful.

>> Maybe another workaround is to define a volatile flag 'thread_complete',
>> initialize it to '0' when thread_B starts and reset to '1' while exit, and
>> just
>> do a value check in the while loop of thread_A should acquire thread_B
>> status.
>> Is this way a bit better?
> Sounds as reasonable workaround for me.
> 
> Kind regards,
> Petr
> 
> [1] https://github.com/kito-cheng/android-checkpoint/blob/master/bionic/0003-bionic-Implement-pthread_tryjoin_np.patch
> 

[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Li Wang]

Alexey Kodanev <aleksei.kodanev@bell-sw.com> wrote:


>
> > Maybe another workaround is to define a volatile flag 'thread_complete',
> > initialize it to '0' when thread_B starts and reset to '1' while exit,
> and just
> > do a value check in the while loop of thread_A should acquire thread_B
> status.
> > Is this way a bit better?
>
> OK, why not, so something like this:
>
> diff --git a/testcases/kernel/crypto/af_alg02.c
> b/testcases/kernel/crypto/af_alg02.c
> index 0f5793c16..1fe0f3bf0 100644
> --- a/testcases/kernel/crypto/af_alg02.c
> +++ b/testcases/kernel/crypto/af_alg02.c
> @@ -18,11 +18,13 @@
>  #include "tst_test.h"
>  #include "tst_af_alg.h"
>  #include "tst_safe_pthread.h"
> +#include "tst_atomic.h"
>  #include <pthread.h>
>  #include <errno.h>
>
>  #define SALSA20_IV_SIZE       8
>  #define SALSA20_MIN_KEY_SIZE  16
> +static int completed;
>
>  static void *verify_encrypt(void *arg)
>  {
> @@ -48,6 +50,8 @@ static void *verify_encrypt(void *arg)
>                 tst_res(TPASS, "Successfully \"encrypted\" an empty
> message");
>         else
>                 tst_res(TFAIL, "read() didn't return 0");
> +
> +       tst_atomic_store(1, &completed);
>         return arg;
>  }
>
> @@ -60,7 +64,7 @@ static void run(void)
>
>         TST_CHECKPOINT_WAIT(0);
>
> -       while (pthread_tryjoin_np(thr, NULL) == EBUSY) {
> +       while (!tst_atomic_load(&completed)) {
>

+1
The atomic method is quite awesome!
-- 
Regards,
Li Wang
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[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Li Wang]

>  #define SALSA20_IV_SIZE       8
>>  #define SALSA20_MIN_KEY_SIZE  16
>> +static int completed;
>>
>>  static void *verify_encrypt(void *arg)
>>  {
>>
>
But we still need to initialize '0' at the start of thread_B,
in case of test running with '-i xx' parameter. Isn't it?

     tst_atomic_store(0, &completed);

-- 
Regards,
Li Wang
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[LTP] [PATCH] crypto/af_alg02: use pthread_tryjoin_np() instead of pthread_kill()

[Alexey Kodanev]

On 16.07.2021 16:21, Li Wang wrote:
> 
>         ?#define SALSA20_IV_SIZE? ? ? ?8
>         ?#define SALSA20_MIN_KEY_SIZE? 16
>         +static int completed;
> 
>         ?static void *verify_encrypt(void *arg)
>         ?{
> 
> 
> But we still need to initialize?'0' at the start of thread_B,
> in case of test?running with '-i xx' parameter. Isn't it?
> 
> ? ???tst_atomic_store(0, &completed);
> 

Yeah, right, and that's another reason to use pthread_tryjoin_np() :)

Because otherwise the thread resources not released... anyway we
could add pthread_join in the end of the run()...


> -- 
> Regards,
> Li Wang