[git commit branch/0.9.33] libc: atexit: reuse free slots at the end of exit functions table

Carmelo Amoroso carmelo.amoroso at st.com
Tue Feb 5 15:00:43 UTC 2013


commit: http://git.uclibc.org/uClibc/commit/?id=893d4fb45bb0811bcc939054e60e37a47a1786c5
branch: http://git.uclibc.org/uClibc/commit/?id=refs/heads/0.9.33

Continuosly dlopen and dlclose of shared object will cause a memory leak
in atexit function. This fix reuse free slots at the end of the list.

For further detail see https://bugs.busybox.net/show_bug.cgi?id=2455

Signed-off-by: Ronald Wahl <ronald.wahl at raritan.com>
Tested-by: Filippo Arcidiacono <filippo.arcidiacono at st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso at st.com>
(cherry picked from commit 389cd96704f21549cafc0b5bdcd0ef762b98bc08)
---
 libc/stdlib/_atexit.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/libc/stdlib/_atexit.c b/libc/stdlib/_atexit.c
index 48b97ff..0af8c57 100644
--- a/libc/stdlib/_atexit.c
+++ b/libc/stdlib/_atexit.c
@@ -240,6 +240,16 @@ struct exit_function attribute_hidden *__new_exitfn(void)
 
     __UCLIBC_MUTEX_LOCK(__atexit_lock);
 
+	/*
+	 * Reuse free slots at the end of the list.
+	 * This avoids eating memory when dlopen and dlclose modules multiple times.
+	*/
+	while (__exit_count > 0) {
+		if (__exit_function_table[__exit_count-1].type == ef_free) {
+			--__exit_count;
+		} else break;
+	}
+
 #ifdef __UCLIBC_DYNAMIC_ATEXIT__
     /* If we are out of function table slots, make some more */
     if (__exit_slots < __exit_count+1) {


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