[asterisk-bugs] [DAHDI-linux 0018422]: dahdi-base locks channel-exporting module in kernel if channel open fails

[Asterisk Bug Tracker]

The following issue has been SUBMITTED. 
====================================================================== 
https://issues.asterisk.org/view.php?id=18422 
====================================================================== 
Reported By:                avarvit
Assigned To:                
====================================================================== 
Project:                    DAHDI-linux
Issue ID:                   18422
Category:                   dahdi (the module)
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
JIRA:                        
Reviewboard Link:            
====================================================================== 
Date Submitted:             2010-12-03 23:21 CST
Last Modified:              2010-12-03 23:21 CST
====================================================================== 
Summary:                    dahdi-base locks channel-exporting module in kernel
if channel open fails
Description: 
Read dahdi-base.c, circa line 2714:
			if (chan->span) {
				if (!try_module_get(chan->span->ops->owner))
					res = -ENXIO;
				else if (chan->span->ops->open)
					res = chan->span->ops->open(chan);
			}
			if (!res) {
				chan->file = file;
				spin_unlock_irqrestore(&chan->lock, flags);
			} else {
				spin_unlock_irqrestore(&chan->lock, flags);
				close_channel(chan);
				clear_bit(DAHDI_FLAGBIT_OPEN, &chan->flags);
			}

If chan->span->ops->open() fails, then DAHDI_FLAGBIT_OPEN never
gets set and module_put is never called on the exporter module.
The following patch fixes the problem (call module_put() if open
fails).

                        if (chan->span) {
                                if (!try_module_get(chan->span->owner))
                                        res = -ENXIO;
                                else if (chan->span->open) { 
                                        res = chan->span->open(chan);
                                        /* avarvit patch */
                                        if (res) {
                                               
module_put(chan->span->owner);
                                        }
                                }
                        }
                        if (!res) {
                                chan->file = file;
                                spin_unlock_irqrestore(&chan->lock,
flags);
                        } else {
                                spin_unlock_irqrestore(&chan->lock,
flags);
                                close_channel(chan);
                                clear_bit(DAHDI_FLAGBIT_OPEN,
&chan->flags);
                        }



====================================================================== 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-12-03 23:21 avarvit        New Issue                                    
======================================================================