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This is an automatically generated e-mail. To reply, visit:
https://reviewboard.asterisk.org/r/3548/
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(Updated June 17, 2014, 6:30 p.m.)
Review request for Asterisk Developers and rmudgett.
Changes
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Follow rmugget's advice (and also actually remove the unneeded counter).
Bugs: ASTERISK-23554
https://issues.asterisk.org/jira/browse/ASTERISK-23554
Repository: Asterisk
Description
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Issue: when a PRI span is disconnected (e.g.: following the unassignment pri
spans) dahdi channels of that span can be destroyed in two different pathes:
1. DAHDI channels are destroyed in response to pri_event_removed
2. The span is destroyed in response to DAHDI_EVENT_REMOVED in the D-channel.
Before the span is destroyed, its channels need to be destroyed.
If the channel is not in a call, (1) is run from the monitor thread, holding
the iflock (lock of iflist: the list of channels). somewhere in the process of
destroying a channel that belongs to a PRI
span, the pri's lock needs to be acquired.
(2) is called from a context of handling the PRI events and hence holds the PRI
lock. Destroying the channels requires getting the iflock.
Which means that if the two happen simultaneously, we have a deadlock. And the
two will happen simultaneously, as recent versions of DAHDI will send an extra
DAHDI_EVENT_REMOVED as a response to any call to the ioctl on DAHDI_GET_EVENT
on a removed span.
This review includes the patches pri_destroy_span_prilist.patch and
sigpri_handle_enodev_1.patch from the referred bug. The former solves this
deadlock by creating a list of spans to be removed "later" and and thus allow
executing (2) without holding the pri lock.
The second patch fixes error handling of libpri: if read returns -ENODEV, we
have no device and it should be destroyed. This, however, requires exposing the
above "deferred destruction" functionality to sig_pri.
Diffs (updated)
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/trunk/channels/sig_pri.c 416446
/trunk/channels/sig_pri.h 416446
/trunk/channels/chan_dahdi.c 416446
Diff: https://reviewboard.asterisk.org/r/3548/diff/
Testing
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Thanks,
Tzafrir Cohen
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