[LTP] [PATCH 1/1] hugeshmctl01: Fix reset stat_time when looping with -i n

[Petr Vorel]

c7a2d296b didn't reset stat_time, thus uninitialized set_shared was
assigned to test variable and test got value from a null pointer,
which leaded to segfault.

hugeshmctl01.c:279: PASS: shmctl in func_rmid() failed as expected, shared memory appears to be removed
tst_checkpoint.c:147: BROK: hugeshmctl01.c:152: tst_checkpoint_wait(0, 10000): ETIMEDOUT (110)
mem.c:817: INFO: set nr_hugepages to 0

dmesg:
segfault at 7f73f8c00000 ip 00000000004051e1 sp 00007ffef375f9a0 error 6 in hugeshmctl01.master[404000+13000]
addr2line -e hugeshmctl01 -f  00000000004051e1
stat_setup
hugeshmctl01.c:139 (discriminator 4)

test = (stat_time == FIRST) ? set_shmat() : set_shared;

/* do an assignement for fun */
*(int *)test = i; // error here

Fixes: c7a2d296b ("hugeshmctl: Use loop from the API")

Reported-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
Suggested-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
Hi Xu,

I'm sorry for introducing a regression.
Thank you for a report and fixing the test.
I'd personally prefer to keep .tcnt = ARRAY_SIZE(tcases),
but maybe others will prefer to keep loop in test_hugeshmctl()
as it was before my change.

BTW it'd be nice to have something like setup_i() and cleanup_i(),
which would be called before/after each run of whole test, when run with
-i n.

Kind regards,
Petr

 .../mem/hugetlb/hugeshmctl/hugeshmctl01.c     | 27 ++++++++++---------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl01.c b/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl01.c
index e6cf8bf09..3b7e14363 100644
--- a/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl01.c
+++ b/testcases/kernel/mem/hugetlb/hugeshmctl/hugeshmctl01.c
@@ -75,6 +75,20 @@ struct tcase {
 
 static void test_hugeshmctl(unsigned int i)
 {
+	stat_time = FIRST;
+
+	/*
+	 * Create a shared memory segment with read and write
+	 * permissions. Do this here instead of in setup()
+	 * so that looping (-i) will work correctly.
+	 */
+	if (i == 0) {
+		shm_id_1 = shmget(shmkey, shm_size,
+				SHM_HUGETLB | IPC_CREAT | IPC_EXCL | SHM_RW);
+		if (shm_id_1 == -1)
+			tst_brk(TBROK | TERRNO, "shmget #main");
+	}
+
 	/*
 	 * if needed, set up any required conditions by
 	 * calling the appropriate setup function
@@ -296,19 +310,6 @@ void setup(void)
 	shm_size = hpage_size * hugepages / 2;
 	update_shm_size(&shm_size);
 	shmkey = getipckey();
-
-	/* initialize stat_time */
-	stat_time = FIRST;
-
-	/*
-	 * Create a shared memory segment with read and write
-	 * permissions.  Do this here instead of in setup()
-	 * so that looping (-i) will work correctly.
-	 */
-	shm_id_1 = shmget(shmkey, shm_size,
-			SHM_HUGETLB | IPC_CREAT | IPC_EXCL | SHM_RW);
-	if (shm_id_1 == -1)
-		tst_brk(TBROK | TERRNO, "shmget #main");
 }
 
 void cleanup(void)
-- 
2.25.1