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lib: do not log_memstats() in crash handler

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`log_memstats()` is not AS-safe.  It can hang the crash handler (or set
your PC on fire, or cause the sun to go supernova - according to POSIX
specs, anyway.)

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
This commit is contained in:
David Lamparter 2024-07-26 16:50:20 -07:00
parent e95fbc1d8c
commit f177663631
1 changed files with 12 additions and 2 deletions
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14
lib/sigevent.c
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@ -237,8 +237,18 @@ core_handler(int signo, siginfo_t *siginfo, void *context)
zlog_signal(signo, "aborting...", siginfo, pc);
/* dump memory stats on core */
log_memstats(stderr, "core_handler");
/* there used to be a log_memstats() call here, to dump MTYPE counters
* on a coredump. This is not possible since log_memstats is not
* AS-Safe, as it calls fopen(), fprintf(), and cousins. This can
* lead to a deadlock depending on where we crashed - very much not a
* good thing if the process just hangs there after a crash.
*
* The alarm(1) above tries to alleviate this, but that's really a
* last resort recovery. Stick with AS-safe calls here.
*
* If the fprintf() calls are removed from log_memstats(), this can be
* added back in, since writing to log with zlog_sigsafe() is AS-safe.
*/
/*
* This is a buffer flush because FRR is going down