RE: Segmentation fault when setting motorStatusProblem_ to 1

[Mark Rivers <rivers@cars.uchicago.edu>]

Ø  What is causing the segmentation fault to occur?

 

You need to obtain a stack trace when the fault occurs.  Are you running on Linux or Windows?  On Linux you can run your program under gdb and when it crashes type the gdb command “backtrace”.  On Windows you need to build for the –debug architecture and then you can use the Visual Studio debugger when it crashes.

 

Mark

 

 

From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Sobhani, Bayan
Sent: Thursday, February 01, 2018 10:17 AM
To: tech-talk@aps.anl.gov
Subject: Segmentation fault when setting motorStatusProblem_ to 1

 

Here is my polling function for the MCS2 driver I am developing:

 

asynStatus SmarActMCS2Axis::poll(bool* moving_p){

        int64_t val;

        comStatus_=getp(channel_,&val);

        if(comStatus_!=asynSuccess){

                *moving_p=false;

               asynPrint(c_p_->pasynUserSelf,ASYN_TRACE_ERROR,"Error reading axis, channel=%d, comstatus=%d!\n", channel_,comStatus_);

                //c_p_ is a pointer to the controller object

                //setIntegerParam(c_p_->motorStatusProblem_,1);

                setIntegerParam(c_p_->motorStatusCommsError_,1);

                callParamCallbacks();

                return asynError;

        }

        val=val/1000;

        setDoubleParam(c_p_->motorEncoderPosition_,(double)val);

        setDoubleParam(c_p_->motorPosition_,(double)val);

        if(is_moving(channel_)==true){

                *moving_p=true;

        }

        else{

                *moving_p=false;

        }

        setIntegerParam(c_p_->motorStatusProblem_,0);

        setIntegerParam(c_p_->motorStatusCommsError_,0);

 

        setIntegerParam(c_p_->motorStatusMoving_,*moving_p);

        setIntegerParam(c_p_->motorStatusDone_, ! *moving_p);

        callParamCallbacks();

        return asynSuccess;

}

 

Notice that “setIntegerParam(c_p_->motorStatusProblem_,1);” is commented out because when I uncomment it, it causes the IOC to have a segmentation fault when I attempt to move an axis that is not connected. Surprisingly, “setIntegerParam(c_p_->motorStatusCommsError_,1);” does not cause the IOC to have a segmentation fault, and as expected raises a COMM alarm when I attempt to move an axis that is not connected. motorStatusProblem and motorStatusCommsError are not referenced anywhere else inside my code. What is causing the segmentation fault to occur?

 

Alex