[asterisk-bugs] [JIRA] (ASTERISK-27090) PJSIP: Deadlock using TCP transport

[Richard Mudgett (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-27090?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Richard Mudgett reassigned ASTERISK-27090:
------------------------------------------

    Assignee: Richard Mudgett

> PJSIP: Deadlock using TCP transport
> -----------------------------------
>
>                 Key: ASTERISK-27090
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-27090
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_pjsip
>    Affects Versions: 13.16.0
>            Reporter: Richard Mudgett
>            Assignee: Richard Mudgett
>         Attachments: backtrace.txt
>
>
> Deadlock due to a lock inversion. In the attached back trace you can see that thread 177 is holding a lock on the transport:
> {noformat}
> #14 0x05a11a62 in ioqueue_dispatch_read_event (ioqueue=0x971de70, h=0x9716588) at ../src/pj/ioqueue_common_abs.c:591
>         read_op = 0xa94e499c
>         bytes_read = 3278
>         has_lock = 1
>         rc = 0
> {noformat}
> This same thread then requests a lock on the dialog 0xaf3a428c:
> {noformat}
> #5  0x08ed4468 in pjsip_dlg_inc_lock (dlg=0xaf3a428c) at ../src/pjsip/sip_dialog.c:847
> {noformat}
>  However the dialog's (0xaf3a428c) lock is being held by thread 53 by the following:
> {noformat}
> #17 0x08ed53ba in pjsip_dlg_send_response (dlg=0xaf3a428c, tsx=0xb6684ec4, tdata=0xb180be84) at ../src/pjsip/sip_dialog.c:1478
>         status = -1234852344
> ......
> #25 0x08ed58c9 in pjsip_dlg_on_rx_request (dlg=0xaf3a428c, rdata=0xb18c7e3c) at ../src/pjsip/sip_dialog.c:1660
>         status = 0
>         tsx = 0xb6684ec4
>         processed = 0
>         i = 1
> {noformat}
> Thread 53 is then waiting on the transport, which is held by thread 177.
> This deadlock happens because the SIP transport being used is TCP and a message on a SIP dialog is being received at the same time as a message on the same SIP dialog is being sent.  If the transport were UDP the deadlock won't happen.



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