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authorArjun Shankar <arjun@redhat.com>2018-10-17 17:47:29 +0200
committerArjun Shankar <arjun@redhat.com>2018-10-17 17:47:29 +0200
commitc5288d378ad258d2e8e8cb174be3b9f233a312eb (patch)
treea987e28461c55a9d7011f046f382beaaa48cc93a /iconv/tst-iconv-mt.c
parent729f34028a7f494b599a29889df825cf826b6de0 (diff)
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Remove unnecessary locking when reading iconv configuration [BZ #22062]
In iconv/gconv_conf.c, __gconv_get_path unnecessarily obtains a lock when populating the array pointed to by __gconv_path_elem. The locking is not necessary because all calls to __gconv_read_conf (which in turn calls __gconv_get_path) are serialized using __libc_once. This patch: - removes all locking in __gconv_get_path; - replaces all explicitly serialized __gconv_read_conf calls with calls to __gconv_load_conf, a new wrapper that is serialized internally; - adds a new test, iconv/tst-iconv_mt.c, to exercise iconv initialization, usage, and cleanup in a multi-threaded program; - indents __gconv_get_path correctly, removing tab characters (which makes the patch look a little bigger than it really is). After removing the unnecessary locking, it was confirmed that the test case fails if the relevant __libc_once is removed. Additionally, four localedata and iconvdata tests also fail. This gives confidence that the testsuite sufficiently guards against some regressions relating to multi-threading with iconv. Tested on x86_64 and i686.
Diffstat (limited to 'iconv/tst-iconv-mt.c')
-rw-r--r--iconv/tst-iconv-mt.c142
1 files changed, 142 insertions, 0 deletions
diff --git a/iconv/tst-iconv-mt.c b/iconv/tst-iconv-mt.c
new file mode 100644
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--- /dev/null
+++ b/iconv/tst-iconv-mt.c
@@ -0,0 +1,142 @@
+/* Test that iconv works in a multi-threaded program.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* This test runs several worker threads that perform the following three
+ steps in staggered synchronization with each other:
+ 1. initialization (iconv_open)
+ 2. conversion (iconv)
+ 3. cleanup (iconv_close)
+ Having several threads synchronously (using pthread_barrier_*) perform
+ these routines exercises iconv code that handles concurrent attempts to
+ initialize and/or read global iconv state (namely configuration). */
+
+#include <iconv.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <support/support.h>
+#include <support/xthread.h>
+#include <support/check.h>
+
+#define TCOUNT 16
+_Static_assert (TCOUNT %2 == 0,
+ "thread count must be even, since we need two groups.");
+
+
+#define CONV_INPUT "Hello, iconv!"
+
+
+pthread_barrier_t sync;
+pthread_barrier_t sync_half_pool;
+
+
+/* Execute iconv_open, iconv and iconv_close in a synchronized way in
+ conjunction with other sibling worker threads. If any step fails, print
+ an error to stdout and return NULL to the main thread to indicate the
+ error. */
+static void *
+worker (void * arg)
+{
+ long int tidx = (long int) arg;
+
+ iconv_t cd;
+
+ char ascii[] = CONV_INPUT;
+ char *inbufpos = ascii;
+ size_t inbytesleft = sizeof (CONV_INPUT);
+
+ char *utf8 = xcalloc (sizeof (CONV_INPUT), 1);
+ char *outbufpos = utf8;
+ size_t outbytesleft = sizeof (CONV_INPUT);
+
+ if (tidx < TCOUNT/2)
+ /* The first half of the worker thread pool synchronize together here,
+ then call iconv_open immediately after. */
+ xpthread_barrier_wait (&sync_half_pool);
+ else
+ /* The second half wait for the first half to finish iconv_open and
+ continue to the next barrier (before the call to iconv below). */
+ xpthread_barrier_wait (&sync);
+
+ /* The above block of code staggers all subsequent pthread_barrier_wait
+ calls in a way that ensures a high chance of encountering these
+ combinations of concurrent iconv usage:
+ 1) concurrent calls to iconv_open,
+ 2) concurrent calls to iconv_open *and* iconv,
+ 3) concurrent calls to iconv,
+ 4) concurrent calls to iconv *and* iconv_close,
+ 5) concurrent calls to iconv_close. */
+
+ cd = iconv_open ("UTF8", "ASCII");
+ TEST_VERIFY_EXIT (cd != (iconv_t) -1);
+
+ xpthread_barrier_wait (&sync);
+
+ TEST_VERIFY_EXIT (iconv (cd, &inbufpos, &inbytesleft, &outbufpos,
+ &outbytesleft)
+ != (size_t) -1);
+
+ *outbufpos = '\0';
+
+ xpthread_barrier_wait (&sync);
+
+ TEST_VERIFY_EXIT (iconv_close (cd) == 0);
+
+ /* The next conditional barrier wait is needed because we staggered the
+ threads into two groups in the beginning and at this point, the second
+ half of worker threads are waiting for the first half to finish
+ iconv_close before they can executing the same: */
+ if (tidx < TCOUNT/2)
+ xpthread_barrier_wait (&sync);
+
+ if (strncmp (utf8, CONV_INPUT, sizeof CONV_INPUT))
+ {
+ printf ("FAIL: thread %lx: invalid conversion output from iconv\n", tidx);
+ pthread_exit ((void *) (long int) 1);
+ }
+
+ pthread_exit (NULL);
+}
+
+
+static int
+do_test (void)
+{
+ pthread_t thread[TCOUNT];
+ void * worker_output;
+ int i;
+
+ xpthread_barrier_init (&sync, NULL, TCOUNT);
+ xpthread_barrier_init (&sync_half_pool, NULL, TCOUNT/2);
+
+ for (i = 0; i < TCOUNT; i++)
+ thread[i] = xpthread_create (NULL, worker, (void *) (long int) i);
+
+ for (i = 0; i < TCOUNT; i++)
+ {
+ worker_output = xpthread_join (thread[i]);
+ TEST_VERIFY_EXIT (worker_output == NULL);
+ }
+
+ xpthread_barrier_destroy (&sync);
+ xpthread_barrier_destroy (&sync_half_pool);
+
+ return 0;
+}
+
+#include <support/test-driver.c>