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From 4da80956418bbe1fdc23cad0b1cbb24cd7b87609 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Patrik=20H=C3=A4gglund?= <patrik.h.hagglund@ericsson.com>
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Date: Sat, 2 Feb 2013 20:21:05 +0100
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Subject: [PATCH] PATCH [perl #106212] Add PL_perlio_mutex to
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atfork_lock/unlock
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Using threads + fork() on Linux, and IO operations in the threads, the
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PL_perlio_mutex may be left in a locked state at the call of fork(),
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potentially leading to deadlock in the child process at subsequent IO
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operations. (Threads are pre-empted and not continued in the child
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process after the fork.)
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Therefore, ensure that the PL_perlio_mutex is unlocked in the child
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process, right after fork(), by using atfork_lock/unlock.
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(The RT text gives ways to reproduce the problem, but are not easily
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added to Perl's test suite)
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---
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util.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/util.c b/util.c
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index 5c695b8..75381f1 100644
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--- a/util.c
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+++ b/util.c
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@@ -2798,6 +2798,9 @@ Perl_atfork_lock(void)
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dVAR;
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#if defined(USE_ITHREADS)
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/* locks must be held in locking order (if any) */
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+# ifdef USE_PERLIO
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+ MUTEX_LOCK(&PL_perlio_mutex);
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+# endif
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# ifdef MYMALLOC
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MUTEX_LOCK(&PL_malloc_mutex);
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# endif
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@@ -2812,6 +2815,9 @@ Perl_atfork_unlock(void)
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dVAR;
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#if defined(USE_ITHREADS)
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/* locks must be released in same order as in atfork_lock() */
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+# ifdef USE_PERLIO
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+ MUTEX_UNLOCK(&PL_perlio_mutex);
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+# endif
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# ifdef MYMALLOC
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MUTEX_UNLOCK(&PL_malloc_mutex);
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# endif
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--
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1.8.1.4
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