[Crash-utility] [PATCH 1/1] Resend CLI list command, print deep structure members

[Alexandr Terekhov]

On Tue, May 19, 2015 at 12:14:49PM -0400, Dave Anderson wrote:
> I've run into three problems dealing with embedded arrays.
> 
> First, should array elements inside an embedded structure be 
> selectable?  For example, the task_struct has an embedded 
> task_rss_stat structure:
> 
.........
>   crash> task -R rss_stat.count[1]
>   PID: 11722  TASK: ffff8801073da5d0  CPU: 2   COMMAND: "crash"
>   task: invalid structure member reference: rss_stat.count[1]
>   crash> 
> 
> Is that expected behavior?

Yes, the new logic consider structure

     count = {0, 0, 0}

in the same way as scalar (you can find the corresponding comment within
parser branches.
+               if ( p && (*s_e != '{' || (*s_e == '{' && buf[len] == '}'))) {
+                       /* Scalar or one-line array
+                        * next = 0x0
+                        *   or
+                        * files = {0x0, 0x0}
+                        */
+                       strcpy(current->value, s_e);
+                       if (trailing_comma) ALLOC_NEXT_ELEMENT;
+               }

Since this type of array is short, I wasn't sure whether it's necessary to
access its elements or not.

> But for some reason, it fails to accept the "pid_link.pid" member:
> 
>   crash> task -R pids[1].pid
>   PID: 11722  TASK: ffff8801073da5d0  CPU: 0   COMMAND: "crash"
>   task: invalid structure member reference: pids[1].pid

This behavior is incorrent, I will check it.

> And third, this behavior also doesn't seem correct.  Here again I select
> just the first element of the task_struct.pids[] array:
>   
>   crash> task -R pids[0].node
>   PID: 11722  TASK: ffff8801073da5d0  CPU: 2   COMMAND: "crash"
>     pids[0].node = {
>       next = 0x0,
>       pprev = 0xffff880105fc9888
>     },
>   
> But it allows me to leave off the "pids[x]" reference, and if so, it defaults
> to the first member of the array:
> 
>   crash> task -R pids.node
>   PID: 11722  TASK: ffff8801073da5d0  CPU: 0   COMMAND: "crash"
>     pids.node = {
>       next = 0x0,
>       pprev = 0xffff880105fc9888
>     },
>   
> Should it reject that syntax?

Yes, it should. I will fix it.

And again, since you've started updating my patch, what is the best way
to provide these fixes?

Thanks,
Alexandr