Re: [LTP] [PATCH] inotify: Add test for inotify mark destruction race

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Jan Kara" <jack@suse.com>
> To: ltp-list@lists.sourceforge.net
> Cc: "Jan Kara" <jack@suse.com>
> Sent: Monday, 27 July, 2015 6:58:27 PM
> Subject: [LTP] [PATCH] inotify: Add test for inotify mark destruction race
> 
> Kernels prior to 4.2 have a race when inode is being deleted while

Hi,

Do you also have the commit id(s) that fix the problem? That might be valuable
information for people who find their kernel crashing.

Regards,
Jan

> inotify group watching that inode is being torn down. When the race is
> hit, the kernel crashes or loops. Test for that race.
> 
> Signed-off-by: Jan Kara <jack@suse.com>
> ---
>  runtest/syscalls                              |   1 +
>  testcases/kernel/syscalls/inotify/inotify06.c | 121
>  ++++++++++++++++++++++++++
>  2 files changed, 122 insertions(+)
>  create mode 100644 testcases/kernel/syscalls/inotify/inotify06.c
> 
> This tests for a kernel bug which causes a crash when triggered. I'm not sure
> how (whether) tests like this should be integrated with LTP. So here is my
> attempt at that.
> 
> diff --git a/runtest/syscalls b/runtest/syscalls
> index 70d4945706ea..c532fe307df9 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -449,6 +449,7 @@ inotify02 inotify02
>  inotify03 inotify03
>  inotify04 inotify04
>  inotify05 inotify05
> +inotify06 inotify06
>  
>  fanotify01 fanotify01
>  fanotify02 fanotify02
> diff --git a/testcases/kernel/syscalls/inotify/inotify06.c
> b/testcases/kernel/syscalls/inotify/inotify06.c
> new file mode 100644
> index 000000000000..d5e14cb7e08d
> --- /dev/null
> +++ b/testcases/kernel/syscalls/inotify/inotify06.c
> @@ -0,0 +1,121 @@
> +#include "config.h"
> +
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <stdlib.h>
> +#include <fcntl.h>
> +#include <time.h>
> +#include <signal.h>
> +#include <sys/inotify.h>
> +#include <sys/time.h>
> +#include <sys/wait.h>
> +#include <sys/syscall.h>
> +
> +#include "test.h"
> +#include "linux_syscall_numbers.h"
> +#include "inotify.h"
> +#include "safe_macros.h"
> +
> +char *TCID = "inotify06";
> +int TST_TOTAL = 1;
> +
> +#if defined(HAVE_SYS_INOTIFY_H)
> +#include <sys/inotify.h>
> +
> +/* Number of seconds to run the test for */
> +#define DURATION 10
> +/* Number of files to test (must be > 1) */
> +#define FILES 5
> +
> +char names[FILES][PATH_MAX];
> +
> +static void cleanup(void)
> +{
> +	tst_rmdir();
> +}
> +
> +static void setup(void)
> +{
> +	int i;
> +
> +	tst_sig(FORK, DEF_HANDLER, cleanup);
> +
> +	TEST_PAUSE;
> +
> +	tst_tmpdir();
> +
> +	for (i = 0; i < FILES; i++)
> +		sprintf(names[i], "fname_%d", i);
> +}
> +
> +int main(int ac, char **av)
> +{
> +	int inotify_fd, fd;
> +	pid_t pid;
> +	time_t start;
> +	int i, lc;
> +
> +	tst_parse_opts(ac, av, NULL, NULL);
> +
> +	setup();
> +
> +	for (lc = 0; TEST_LOOPING(lc); lc++) {
> +		pid = fork();
> +		if (pid == 0) {
> +			while (1) {
> +				for (i = 0; i < FILES; i++) {
> +					fd = SAFE_OPEN(cleanup, names[i],
> +						       O_CREAT | O_RDWR, 0600);
> +					SAFE_CLOSE(cleanup, fd);
> +				}
> +				for (i = 0; i < FILES; i++)
> +					SAFE_UNLINK(cleanup, names[i]);
> +			}
> +		} else if (pid == -1)
> +			tst_brkm(TBROK | TERRNO, cleanup, "fork() failed");
> +
> +		start = time(NULL);
> +		while (time(NULL) - start < DURATION) {
> +			inotify_fd = syscall(__NR_inotify_init1, O_NONBLOCK);
> +			if (inotify_fd < 0) {
> +				if (errno == ENOSYS) {
> +					tst_brkm(TCONF, cleanup,
> +					 	 "inotify is not configured in this "
> +						 "kernel.");
> +				} else {
> +					tst_brkm(TBROK | TERRNO, cleanup,
> +						 "inotify_init failed");
> +				}
> +			}
> +			for (i = 0; i < FILES; i++) {
> +				/*
> +				 * Both failure and success are fine since
> +				 * files are being deleted in parallel - this
> +				 * is what provokes the race we want to test
> +				 * for...
> +				 */
> +				myinotify_add_watch(inotify_fd, names[i],
> +						    IN_MODIFY);
> +			}
> +			SAFE_CLOSE(cleanup, inotify_fd);
> +		}
> +		/* We survived for given time - test succeeded */
> +		tst_resm(TPASS, "kernel survived inotify beating");
> +
> +		/* Kill the child creating / deleting files and wait for it */
> +		kill(pid, SIGKILL);
> +		wait(NULL);
> +	}
> +
> +	cleanup();
> +	tst_exit();
> +}
> +
> +#else
> +
> +int main(void)
> +{
> +	tst_brkm(TCONF, NULL, "system doesn't have required inotify support");
> +}
> +
> +#endif
> --
> 2.1.4
> 
> 
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