[asterisk-dev] [Code Review] 4502: Improved and portable ast_log recursion avoidance

[Corey Farrell]

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Review request for Asterisk Developers.


Bugs: ASTERISK-24155
    https://issues.asterisk.org/jira/browse/ASTERISK-24155


Repository: Asterisk


Description
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This introduces a new logger routine ast_log_safe.  This routine should be used for all error messages in code that can be run as a result of ast_log.  ast_log_safe does nothing if run recursively or from the logger thread.  All error logging in astobj2.c, strings.c and utils.h have been switched to ast_log_safe.  One ast_log from stringfields code in utils.c was also changed.

I've also added support for raw threadstorage.  This provides direct access to the void* pointer in threadstorage.  In ast_log_safe I use NULL to signify that this thread is not already running ast_log_safe, (void*)1 when it is already running.  This was done since it's critical that ast_log_safe do nothing that could log during recursion checking.

This review shows the version 13 patch.  Version 11 didn't have the backtrace check for MALLOC_FAILURE_MSG, and trunk uses 'ast_callid' instead of 'struct ast_callid *'.  Patches for each version are on JIRA.

The idea to use threadstorage to protect certain error logging came from the patch posted by Timo Teräs.


Diffs
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  /branches/13/main/utils.c 432991 
  /branches/13/main/strings.c 432991 
  /branches/13/main/logger.c 432991 
  /branches/13/main/hashtab.c 432991 
  /branches/13/main/astobj2.c 432991 
  /branches/13/include/asterisk/utils.h 432991 
  /branches/13/include/asterisk/threadstorage.h 432991 
  /branches/13/include/asterisk/logger.h 432991 

Diff: https://reviewboard.asterisk.org/r/4502/diff/


Testing
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Verified with 'nm -g main/astobj2.o' that ast_log_safe was being used.

Tested by further modifying Asterisk with added calls to ast_log_safe().
* In main() after fully booted.
* In ast_log_safe() after setting in_safe_log.
* From the logger thread.

Only the message after fully booted was shown in the logs, all others were ignored.


Thanks,

Corey Farrell

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