Resume threads

["Brethour, Tanya (tonic)" <tonic at sequent dot com>]

(FYI - Resubmitting to this mailing list)

> Hello!
> 
> I have a quick question regarding resuming threads. I am currently porting
> gdb 5.0 to ptx 4.5+ and I am having some trouble getting the threads to
> resume properly.
> 
> My question is not a ptx specific question.. but more a GDB question (how
> is it supposed to work).
> 
> Currently.. I am using a test program that creates 10 threads and they each
> call this "Stress" function that does some memory allocation and
> dealllocation stress test. I set a breakpoint at stress.. and let gdb fly.
> The problem is.. that after it creates the last thread.. it tries to write
> to memory (I am assuming this is the breakpoint stuff because they should
> all be stopped in Stress at this point) and the thread (inferior_pid) is
> NOT stopped. So I get errors when writing to memory and the thread is not
> stopped.
> 
> Now.. my ptx_thread_resume function.. resumes either the inferior_pid or
> ALL the threads.. depending on the pid it is passed. -1 means to resume all
> threads (or so I think...). So when its -1 I call iterate_over_threads and
> either resume them all.. or step the inferior pid thread (and resume the
> rest).
> 
> Now being new to GDB.. I might have the different cases messed up. What I
> mean.. is that -1 might not mean to resume all threads.. etc. So I am
> hoping someone can help.
> 
> In addition.. I have played around with my create_inferior function.. and
> placed the add_thread(inferior_pid) either before or after the proceed
> call. When it is placed after the proceed call.. gdb hangs because my
> resume function.. never resumes the inferior_pid because pid=-1 and it is
> not in the thread list. However.. if I placed it before.. I get the issue I
> talked about above.. where I can not write memory because my thread is not
> stopped!
> 
> The bottom line is: Does anyone have an idea how resume is supposed to work
> with threads? Do I have the right idea? And if so.. why would I get errors?
> If I do not have the concept correct.. please let me know! In addition..
> should the inferior_pid be added before or after the proceed call in the
> create_inferior function. See below ..I have pasted my code:
> 
> 
> Thanks,
> Tanya
> 
> struct resumeHLPR
> {
>   int step;
>   int signo;
> };
> 
> static int ptx_thread_resumeHLPR (struct thread_info *tp, struct resumeHLPR
> *resumeinfo)
> {
>   int Error =0 ;
>   int pid = 0;
>   int lwpid = 0;
> 
>   /*Lets get pid, lwpid from tp->pid*/
>   pid = PIDGET(tp->pid);
>   lwpid = TIDGET(tp->pid);
> 
>   
>   if (resumeinfo->step && tp->pid == inferior_pid)
>     {
>       Error= lwp_trace(TRC_STEP_LWP,pid,lwpid,0,0,0,0);
>       /*printf("Step - PID:%X  LWPID:%X\n",pid,lwpid);*/
>     }
>   else
>     {
>       Error= lwp_trace(TRC_RESUME_LWP,pid,lwpid,0,0,
> 		     tp->pid == inferior_pid ? resumeinfo->signo : 0, 0); 
>       /*printf("Resume - PID:%X  LWPID:%X\n",pid,lwpid);*/
>     }
> 
> 
>  return 0;
> }
> 
> 
> 
> static void ptx_thread_resume (pid, step, signo)
>      int pid;
>      int step;
>      enum target_signal signo;
> {
> 
>   int Error=0;
>   int lwpid=0;
>   int savepid = 0;
>   
>   struct resumeHLPR rinfo;
>   rinfo.step = step;
>   rinfo.signo = signo;
> 
>   if(pid == -1)
>     {
>       iterate_over_threads(ptx_thread_resumeHLPR,&rinfo);
>     }
>   
>   else
>     {
>       pid = PIDGET(inferior_pid);
>   
>       lwpid = TIDGET(inferior_pid);
>   
>   
>       if(step)
>       {
> 	Error= lwp_trace(TRC_STEP_LWP,pid,lwpid,0,0,0,0); 
> 	printf("Step - PID:%X  LWPID:%X\n",pid,lwpid);
>       }
>       else
>       {
> 	Error= lwp_trace(TRC_RESUME_LWP,pid,lwpid,0,0,signo,0); 
> 	printf("Resume - PID:%X  LWPID:%X\n",pid,lwpid);
>       }
>       
>       if(Error)
>       printf("Resume_thread %s\n",strerror(Error));
>       
>       }
>  
> }
> 
> static void
> ptx_thread_create_inferior (exec_file, allargs, env)
>      char *exec_file;
>      char *allargs;
>      char **env;
> {
> 
>  
>   fork_inferior (exec_file, allargs, env, lwptrace_me,
> 		 lwptrace_him, NULL,  NULL);
>   
>    
>   
>   proceed ((CORE_ADDR) -1, TARGET_SIGNAL_0, 0);
>   push_target (&ptx_thread_ops);
> 
>   add_thread (inferior_pid);
> 
> }
> 
>