[PATCH rtems6 - v1 06/16] Flashdev: Make mutex name more generic

[Bernd Moessner]

On 04.01.2024 19:55, Kinsey Moore wrote:
> On Thu, Jan 4, 2024 at 12:35 PM <berndmoessner80 at gmail.com> wrote:
>
>     From: Bernd Moessner <berndmoessner80 at gmail.com>
>
>     ---
>      cpukit/dev/flash/flashdev.c | 5 ++++-
>      1 file changed, 4 insertions(+), 1 deletion(-)
>
>     diff --git a/cpukit/dev/flash/flashdev.c b/cpukit/dev/flash/flashdev.c
>     index 8bd3d11246..0020e8d2c1 100644
>     --- a/cpukit/dev/flash/flashdev.c
>     +++ b/cpukit/dev/flash/flashdev.c
>     @@ -34,6 +34,7 @@
>
>      #include <errno.h>
>      #include <fcntl.h>
>     +#include <stdio.h>
>      #include <stdlib.h>
>      #include <string.h>
>      #include <unistd.h>
>     @@ -490,7 +491,9 @@ static int rtems_flashdev_do_init(
>        void ( *destroy )( rtems_flashdev *flash )
>      )
>      {
>     -  rtems_recursive_mutex_init( &flash->mutex, "RTEMS_FLASHDEV
>     Flash" );
>     +  char mtx_name[19];
>     +  sprintf(mtx_name, "FDEV_MTX_%08x", (unsigned int) flash);
>     +  rtems_recursive_mutex_init( &flash->mutex, (const char*)
>     &mtx_name );
>
>
> None of the other uses of mutexes in cpukit differentiate between 
> various instantiations and the information you've added here is 
> already available if you know the mutex address and know that it's a 
> flash mutex.
>
> Is there a reason this needs to differentiate between the various 
> instances where others don't?
>
> Kinsey


I already know that i will require two instances of flashedev.

I had two thoughts on my mind:

a)  I was worried that creating two mutex with the same name could cause 
problems

b) Not sure if that already exists for RTEMS but I had those debug views 
in mind where you can immediately see all kernel objects (tasks, mutex, 
etc.).


Therefore, I thought about a way to make the mutex name unique.

Note: You've hit the weak spot and I've changed the implementation in a 
later patch. Perhaps, I have completely misunderstood the docs:

https://docs.rtems.org/branches/master/c-user/self_contained_objects.html

The|name|must be persistent throughout the life-time of the mutex. 
A|name|of|NULL|is valid. The mutex is unlocked after initialization.

Things worked out on my side, but I the "persistent" made me a worry 
about the fact that mtx_name goes out scope. Therefore, I've added the 
required buffer to the flashdev struct to store the name there.


I am open for all solutions: keeping Aarons implementation, passing NULL 
as name, better ideas to create unique names.