[LTP] [PATCH v2 2/2] syscalls/shmget06: Add test when shm_next_id is already in use

[xuyang2018.jy@fujitsu.com <xuyang2018.jy@fujitsu.com>]

Hi Cyril

I have merged this patchset, thanks for your review.

Best Regards
Yang Xu
> When the identifier of the System V shared memory segment that shm_next_id stored
> is already in use, shmget() with different key will return the another shm id. But
> kernel doesn't guarantee desired id, I just compare with the existed id, if not
> equal, the test succeeds.
> 
> This case is similar to msgget05.c.
> 
> Reviewed-by: Cyril Hrubis<chrubis@suse.cz>
> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
> ---
>   runtest/syscalls                              |  1 +
>   runtest/syscalls-ipc                          |  1 +
>   .../kernel/syscalls/ipc/shmget/.gitignore     |  1 +
>   .../kernel/syscalls/ipc/shmget/shmget06.c     | 75 +++++++++++++++++++
>   4 files changed, 78 insertions(+)
>   create mode 100644 testcases/kernel/syscalls/ipc/shmget/shmget06.c
> 
> diff --git a/runtest/syscalls b/runtest/syscalls
> index b65b18c32..b379b2d90 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -1413,6 +1413,7 @@ shmget02 shmget02
>   shmget03 shmget03
>   shmget04 shmget04
>   shmget05 shmget05
> +shmget06 shmget06
> 
>   sigaction01 sigaction01
>   sigaction02 sigaction02
> diff --git a/runtest/syscalls-ipc b/runtest/syscalls-ipc
> index ff0364704..b758158c3 100644
> --- a/runtest/syscalls-ipc
> +++ b/runtest/syscalls-ipc
> @@ -68,3 +68,4 @@ shmget02 shmget02
>   shmget03 shmget03
>   shmget04 shmget04
>   shmget05 shmget05
> +shmget06 shmget06
> diff --git a/testcases/kernel/syscalls/ipc/shmget/.gitignore b/testcases/kernel/syscalls/ipc/shmget/.gitignore
> index 6f08529f8..768d1c69d 100644
> --- a/testcases/kernel/syscalls/ipc/shmget/.gitignore
> +++ b/testcases/kernel/syscalls/ipc/shmget/.gitignore
> @@ -2,3 +2,4 @@
>   /shmget03
>   /shmget04
>   /shmget05
> +/shmget06
> diff --git a/testcases/kernel/syscalls/ipc/shmget/shmget06.c b/testcases/kernel/syscalls/ipc/shmget/shmget06.c
> new file mode 100644
> index 000000000..d91b7b635
> --- /dev/null
> +++ b/testcases/kernel/syscalls/ipc/shmget/shmget06.c
> @@ -0,0 +1,75 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2021 FUJITSU LIMITED. All rights reserved.
> + * Author: Yang Xu<xuyang2018.jy@fujitsu.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * It is a basic test for shm_next_id.
> + *
> + * When the shared memory segment identifier that shm_next_id stored is already
> + * in use, call shmget with different key just use another unused value in range
> + * [0,INT_MAX]. Kernel doesn't guarantee the desired id.
> + */
> +
> +#include<errno.h>
> +#include<string.h>
> +#include<sys/types.h>
> +#include<sys/ipc.h>
> +#include<sys/shm.h>
> +#include "tst_test.h"
> +#include "tst_safe_sysv_ipc.h"
> +#include "libnewipc.h"
> +
> +#define NEXT_ID_PATH "/proc/sys/kernel/shm_next_id"
> +
> +static int shm_id[2], pid;
> +static key_t shmkey[2];
> +
> +static void verify_shmget(void)
> +{
> +	SAFE_FILE_PRINTF(NEXT_ID_PATH, "%d", shm_id[0]);
> +
> +	shm_id[1] = SAFE_SHMGET(shmkey[1], SHM_SIZE, IPC_CREAT | SHM_RW);
> +	if (shm_id[1] == shm_id[0])
> +		tst_res(TFAIL, "shm id %d has existed, shmget() returns the"
> +			" same shm id unexpectedly", shm_id[0]);
> +	else
> +		tst_res(TPASS, "shm id %d has existed, shmget() returns the"
> +			" new shm id %d", shm_id[0], shm_id[1]);
> +
> +	SAFE_SHMCTL(shm_id[1], IPC_RMID, NULL);
> +}
> +
> +static void setup(void)
> +{
> +	shmkey[0] = GETIPCKEY();
> +	shmkey[1] = GETIPCKEY();
> +	pid = getpid();
> +	SAFE_FILE_PRINTF(NEXT_ID_PATH, "%d", pid);
> +	shm_id[0] = SAFE_SHMGET(shmkey[0], SHM_SIZE, IPC_CREAT | SHM_RW);
> +}
> +
> +static void cleanup(void)
> +{
> +	int i;
> +
> +	for (i = 0; i<  2; i++) {
> +		if (shm_id[i] != -1)
> +			SAFE_SHMCTL(shm_id[i], IPC_RMID, NULL);
> +	}
> +}
> +
> +static struct tst_test test = {
> +	.needs_tmpdir = 1,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.test_all = verify_shmget,
> +	.needs_kconfigs = (const char *[]) {
> +		"CONFIG_CHECKPOINT_RESTORE=y",
> +		NULL
> +	},
> +	.needs_root = 1,
> +};