Hi Ernesto,
ext Ramos Falcon, Ernesto wrote:
> Hi,
>
> We have detected a use case where if an application creates a child process
> using fork call, and then the child and father processes call
> DSPProcessor_Attach() and create a new process context with new tgid; when
> the processes are terminated, only the last process calls bridge_release
> cleaning only the resources in the father process, leaving the child
> resources unreleased.
>
> One solution we have seen is to perform goes through the entire process
> context list, clean up all the resources for all terminated processes or in
> "zombie" state, as below,
>
> DRV_GetProcCtxtList(&pCtxtclosed, (struct DRV_OBJECT *)hDrvObject);
> while (pCtxtclosed != NULL) {
> printk("pCtxtclosed->pid = %d\n",pCtxtclosed->pid);
> tsk = find_task_by_pid(pCtxtclosed->pid);
>
> if ((tsk == NULL) || (tsk->exit_state == EXIT_ZOMBIE)) {
>
> GT_1trace(driverTrace, GT_5CLASS,
> "***Task structure not existing for "
> "process***%d\n", pCtxtclosed->pid);
> DRV_RemoveAllResources(pCtxtclosed);
> if (pCtxtclosed->hProcessor != NULL) {
> PROC_Detach
> (pCtxtclosed->hProcessor);
> }
> pTmp = pCtxtclosed->next;
> DRV_RemoveProcContext((struct DRV_OBJECT *)hDrvObject,
> pCtxtclosed,
> (void *)pCtxtclosed->pid);
> } else {
> pTmp = pCtxtclosed->next;
> }
> pCtxtclosed = pTmp;
> }
>
> Please let me know your comments.
>
> /Ernesto
Good point :)
I would like to simplify this use case ;)
If we call DSPProcessor_Attach() twice in the same process and kill the process,
then it will leak memory for 1st instance of PROCESSOR object.
When we call open() on /dev/DspBridge a new PROCESS_CONTEXT is allocated, and it
should be allocated **only once** in bridge_open() unlike in NODE_Allocate() and
PROC_Attach(). PROCESS_CONTEXT tracks all the resources allocated on behalf of
an open file handle(and not the process / thread). When this handle is closed
all these resources should be freed in bridge_release(). Accountability of
resources should be done using PROCESS_CONTEXT and **not pid (which will be
different for different thread) / tgid (which will be different for parent and
child).
Above problem occurs because PROCESS_CONTEXT by design tracks only one PROCESSOR
object which gets freed in bridge_release().
Let me know your comments on this, and then we can proceed to fix this issue.
Cheers,
Ameya.
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