* [Xenomai] Multiple processes within same session
@ 2016-09-06 15:38 Tobias Luksch
2016-09-11 13:29 ` Philippe Gerum
2016-09-13 7:37 ` Philippe Gerum
0 siblings, 2 replies; 4+ messages in thread
From: Tobias Luksch @ 2016-09-06 15:38 UTC (permalink / raw)
To: xenomai
Hello,
[Arch:x86, Processor:Corei7, Kernel: 4.1.18, Xenomai:3.0.2]
we are using several Xenomai processes communicating using shared memory (rt_heap) and a few named mutexes. The processes also create additional unnamed task, mutexes, semaphores, etc.
After porting to Xenomai 3, I see the following problem: To access the shared heap, I start two processes within the same session (--session from command line). Shared access to the heap works, but when creating unnamed objects, e.g. a mutex, in the second process, rt_mutex_create returns -17.
Here is a small example program to reproduce this:
#include <alchemy/task.h>
#include <alchemy/mutex.h>
#include <stdio.h>
int main(int argc, char* argv[])
{
rt_printf("hello world\n");
RT_MUTEX mutex;
int ret_val = rt_mutex_create( &mutex, NULL );
rt_printf( "rt_mutex_create: %d\n", ret_val );
while (true)
{
rt_task_sleep(1000000000);
rt_printf("ping\n");
}
return 0;
}
Starting this program (called xeno-test here) once gives:
$ ./xeno-test --session=test
hello world
rt_mutex_create: 0
ping
ping
[..]
Starting it a second time with the same session:
$ ./xeno-test --session=test
hello world
rt_mutex_create: -17
ping
ping
[..]
Starting the program another time with a different session works without error. Also using differently named mutexes for both instances works.
I am not sure about the naming mechanism (if any) when creating unnamed objects like mutexes, nor about what is actually shared between processes when using the same session. It would be great if anyone could give some details on this.
Any help would be appreciated.
Best regards,
Tobias
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Xenomai] Multiple processes within same session 2016-09-06 15:38 [Xenomai] Multiple processes within same session Tobias Luksch @ 2016-09-11 13:29 ` Philippe Gerum 2016-09-13 7:37 ` Philippe Gerum 1 sibling, 0 replies; 4+ messages in thread From: Philippe Gerum @ 2016-09-11 13:29 UTC (permalink / raw) To: Tobias Luksch, xenomai On 09/06/2016 05:38 PM, Tobias Luksch wrote: > Hello, > > [Arch:x86, Processor:Corei7, Kernel: 4.1.18, Xenomai:3.0.2] > > we are using several Xenomai processes communicating using shared memory (rt_heap) and a few named mutexes. The processes also create additional unnamed task, mutexes, semaphores, etc. > After porting to Xenomai 3, I see the following problem: To access the shared heap, I start two processes within the same session (--session from command line). Shared access to the heap works, but when creating unnamed objects, e.g. a mutex, in the second process, rt_mutex_create returns -17. > > Here is a small example program to reproduce this: > > #include <alchemy/task.h> > #include <alchemy/mutex.h> > #include <stdio.h> > > int main(int argc, char* argv[]) > { > rt_printf("hello world\n"); > RT_MUTEX mutex; > int ret_val = rt_mutex_create( &mutex, NULL ); > rt_printf( "rt_mutex_create: %d\n", ret_val ); > > while (true) > { > rt_task_sleep(1000000000); > rt_printf("ping\n"); > } > return 0; > } > > Starting this program (called xeno-test here) once gives: > $ ./xeno-test --session=test > hello world > rt_mutex_create: 0 > ping > ping > [..] > > Starting it a second time with the same session: > $ ./xeno-test --session=test > hello world > rt_mutex_create: -17 > ping > ping > [..] > > Starting the program another time with a different session works without error. Also using differently named mutexes for both instances works. > > I am not sure about the naming mechanism (if any) when creating unnamed objects like mutexes, nor about what is actually shared between processes when using the same session. It would be great if anyone could give some details on this. > > Any help would be appreciated. This is a shortcoming of the internal no-so-random name generator used for anon objects in lib/alchemy: it should use a shared counter when running in pshared mode for drawing unique names, but currently uses a process-private one which is wrong. Hence the -EEXIST error received when two processes draw the same private counter value, which is likely. As a work around, you could provide named mutexes based on a sequence number and the current pid value, until the name generator is fixed in mainline. -- Philippe. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Xenomai] Multiple processes within same session 2016-09-06 15:38 [Xenomai] Multiple processes within same session Tobias Luksch 2016-09-11 13:29 ` Philippe Gerum @ 2016-09-13 7:37 ` Philippe Gerum 2016-09-13 8:48 ` Tobias Luksch 1 sibling, 1 reply; 4+ messages in thread From: Philippe Gerum @ 2016-09-13 7:37 UTC (permalink / raw) To: Tobias Luksch, xenomai On 09/06/2016 05:38 PM, Tobias Luksch wrote: > Hello, > > [Arch:x86, Processor:Corei7, Kernel: 4.1.18, Xenomai:3.0.2] > > we are using several Xenomai processes communicating using shared memory (rt_heap) and a few named mutexes. The processes also create additional unnamed task, mutexes, semaphores, etc. > After porting to Xenomai 3, I see the following problem: To access the shared heap, I start two processes within the same session (--session from command line). Shared access to the heap works, but when creating unnamed objects, e.g. a mutex, in the second process, rt_mutex_create returns -17. > > Here is a small example program to reproduce this: > > #include <alchemy/task.h> > #include <alchemy/mutex.h> > #include <stdio.h> > > int main(int argc, char* argv[]) > { > rt_printf("hello world\n"); > RT_MUTEX mutex; > int ret_val = rt_mutex_create( &mutex, NULL ); > rt_printf( "rt_mutex_create: %d\n", ret_val ); > > while (true) > { > rt_task_sleep(1000000000); > rt_printf("ping\n"); > } > return 0; > } > > Starting this program (called xeno-test here) once gives: > $ ./xeno-test --session=test > hello world > rt_mutex_create: 0 > ping > ping > [..] > > Starting it a second time with the same session: > $ ./xeno-test --session=test > hello world > rt_mutex_create: -17 > ping > ping > [..] > > Starting the program another time with a different session works without error. Also using differently named mutexes for both instances works. > > I am not sure about the naming mechanism (if any) when creating unnamed objects like mutexes, nor about what is actually shared between processes when using the same session. It would be great if anyone could give some details on this. > > Any help would be appreciated. This patch should address the issue: commit e539ab0b1db5ca56f8d3db39d2ca0bdf009c9b25 Author: Philippe Gerum <rpm@xenomai.org> Date: Tue Sep 13 09:36:11 2016 +0200 boilerplate/ancillaries: fix unique name generation in pshared mode diff --git a/lib/boilerplate/ancillaries.c b/lib/boilerplate/ancillaries.c index a811a40..0f469a4 100644 --- a/lib/boilerplate/ancillaries.c +++ b/lib/boilerplate/ancillaries.c @@ -231,7 +231,11 @@ char *generate_name(char *buf, const char *radix, buf[len] = '\0'; } else { tag = atomic_add_fetch(&ngen->serial, 1); +#ifdef CONFIG_XENO_PSHARED + snprintf(buf, len, "%s@%d[%d]", ngen->radix, tag, __node_id); +#else snprintf(buf, len, "%s@%d", ngen->radix, tag); +#endif } return buf; -- Philippe. ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Xenomai] Multiple processes within same session 2016-09-13 7:37 ` Philippe Gerum @ 2016-09-13 8:48 ` Tobias Luksch 0 siblings, 0 replies; 4+ messages in thread From: Tobias Luksch @ 2016-09-13 8:48 UTC (permalink / raw) To: Philippe Gerum, xenomai > On 09/06/2016 05:38 PM, Tobias Luksch wrote: > > Hello, > > > > [Arch:x86, Processor:Corei7, Kernel: 4.1.18, Xenomai:3.0.2] > > > > we are using several Xenomai processes communicating using shared > memory (rt_heap) and a few named mutexes. The processes also create > additional unnamed task, mutexes, semaphores, etc. > > After porting to Xenomai 3, I see the following problem: To access the > shared heap, I start two processes within the same session (--session from > command line). Shared access to the heap works, but when creating > unnamed objects, e.g. a mutex, in the second process, rt_mutex_create > returns -17. > > > > Here is a small example program to reproduce this: > > > > #include <alchemy/task.h> > > #include <alchemy/mutex.h> > > #include <stdio.h> > > > > int main(int argc, char* argv[]) > > { > > rt_printf("hello world\n"); > > RT_MUTEX mutex; > > int ret_val = rt_mutex_create( &mutex, NULL ); > > rt_printf( "rt_mutex_create: %d\n", ret_val ); > > > > while (true) > > { > > rt_task_sleep(1000000000); > > rt_printf("ping\n"); > > } > > return 0; > > } > > > > Starting this program (called xeno-test here) once gives: > > $ ./xeno-test --session=test > > hello world > > rt_mutex_create: 0 > > ping > > ping > > [..] > > > > Starting it a second time with the same session: > > $ ./xeno-test --session=test > > hello world > > rt_mutex_create: -17 > > ping > > ping > > [..] > > > > Starting the program another time with a different session works without > error. Also using differently named mutexes for both instances works. > > > > I am not sure about the naming mechanism (if any) when creating > unnamed objects like mutexes, nor about what is actually shared between > processes when using the same session. It would be great if anyone could > give some details on this. > > > > Any help would be appreciated. > > This patch should address the issue: > > commit e539ab0b1db5ca56f8d3db39d2ca0bdf009c9b25 > Author: Philippe Gerum <rpm@xenomai.org> > Date: Tue Sep 13 09:36:11 2016 +0200 > > boilerplate/ancillaries: fix unique name generation in pshared mode > > diff --git a/lib/boilerplate/ancillaries.c b/lib/boilerplate/ancillaries.c > index a811a40..0f469a4 100644 > --- a/lib/boilerplate/ancillaries.c > +++ b/lib/boilerplate/ancillaries.c > @@ -231,7 +231,11 @@ char *generate_name(char *buf, const char *radix, > buf[len] = '\0'; > } else { > tag = atomic_add_fetch(&ngen->serial, 1); > +#ifdef CONFIG_XENO_PSHARED > + snprintf(buf, len, "%s@%d[%d]", ngen->radix, tag, > __node_id); > +#else > snprintf(buf, len, "%s@%d", ngen->radix, tag); > +#endif > } > > return buf; > Thank you for the patch, we will test it soon and give feedback on the result. Tobias ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-09-13 8:48 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2016-09-06 15:38 [Xenomai] Multiple processes within same session Tobias Luksch 2016-09-11 13:29 ` Philippe Gerum 2016-09-13 7:37 ` Philippe Gerum 2016-09-13 8:48 ` Tobias Luksch
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