Re: [PATCH RFC 2/2] Add selftests for pidfd polling
On Thu, Apr 11, 2019 at 01:50:43PM -0400, Joel Fernandes (Google) wrote:
> Other than verifying pidfd based polling, the tests make sure that
> wait semantics are preserved with the pidfd poll. Notably the 2 cases:
> 1. If a thread group leader exits while threads still there, then no
>pidfd poll notifcation should happen.
> 2. If a non-thread group leader does an execve, then the thread group
>leader is signaled to exit and is replaced with the execing thread
>as the new leader, however the parent is not notified in this case.
>
> Signed-off-by: Joel Fernandes (Google)
> ---
> tools/testing/selftests/pidfd/Makefile | 2 +-
> tools/testing/selftests/pidfd/pidfd_test.c | 216 -
> 2 files changed, 208 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/pidfd/Makefile
> b/tools/testing/selftests/pidfd/Makefile
> index deaf8073bc06..4b31c14f273c 100644
> --- a/tools/testing/selftests/pidfd/Makefile
> +++ b/tools/testing/selftests/pidfd/Makefile
> @@ -1,4 +1,4 @@
> -CFLAGS += -g -I../../../../usr/include/
> +CFLAGS += -g -I../../../../usr/include/ -lpthread
>
> TEST_GEN_PROGS := pidfd_test
>
> diff --git a/tools/testing/selftests/pidfd/pidfd_test.c
> b/tools/testing/selftests/pidfd/pidfd_test.c
> index d59378a93782..4d5206280091 100644
> --- a/tools/testing/selftests/pidfd/pidfd_test.c
> +++ b/tools/testing/selftests/pidfd/pidfd_test.c
> @@ -4,18 +4,26 @@
> #include
> #include
> #include
> +#include
> #include
> #include
> #include
> #include
> #include
> #include
> +#include
> +#include
> #include
> #include
> +#include
> #include
>
> #include "../kselftest.h"
>
> +#define CHILD_THREAD_MIN_WAIT 3 /* seconds */
> +#define MAX_EVENTS 5
> +#define __NR_pidfd_send_signal 424
> +
> static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
> unsigned int flags)
> {
> @@ -30,6 +38,22 @@ static void set_signal_received_on_sigusr1(int sig)
> signal_received = 1;
> }
>
> +static int open_pidfd(const char *test_name, pid_t pid)
> +{
> + char buf[256];
> + int pidfd;
> +
> + snprintf(buf, sizeof(buf), "/proc/%d", pid);
> + pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
> +
> + if (pidfd < 0)
> + ksft_exit_fail_msg(
> + "%s test: Failed to open process file descriptor\n",
> + test_name);
> +
> + return pidfd;
> +}
> +
> /*
> * Straightforward test to see whether pidfd_send_signal() works is to send
> * a signal to ourself.
> @@ -87,7 +111,6 @@ static int wait_for_pid(pid_t pid)
> static int test_pidfd_send_signal_exited_fail(void)
> {
> int pidfd, ret, saved_errno;
> - char buf[256];
> pid_t pid;
> const char *test_name = "pidfd_send_signal signal exited process";
>
> @@ -99,17 +122,10 @@ static int test_pidfd_send_signal_exited_fail(void)
> if (pid == 0)
> _exit(EXIT_SUCCESS);
>
> - snprintf(buf, sizeof(buf), "/proc/%d", pid);
> -
> - pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
> + pidfd = open_pidfd(test_name, pid);
>
> (void)wait_for_pid(pid);
>
> - if (pidfd < 0)
> - ksft_exit_fail_msg(
> - "%s test: Failed to open process file descriptor\n",
> - test_name);
> -
> ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
> saved_errno = errno;
> close(pidfd);
> @@ -368,10 +384,192 @@ static int test_pidfd_send_signal_syscall_support(void)
> return 0;
> }
>
> +void *test_pidfd_poll_exec_thread(void *priv)
I think you can do static here?
> +{
> + char waittime[256];
> +
> + ksft_print_msg("Child Thread: starting. pid %d tid %d ; and sleeping\n",
> + getpid(), syscall(SYS_gettid));
> + ksft_print_msg("Child Thread: doing exec of sleep\n");
> +
> + sprintf(waittime, "%d", CHILD_THREAD_MIN_WAIT);
> + execl("/bin/sleep", "sleep", waittime, (char *)NULL);
> +
> + ksft_print_msg("Child Thread: DONE. pid %d tid %d\n",
> + getpid(), syscall(SYS_gettid));
You execl(), but then print stuff after that? Might also be worth
switching to execlp().
> + return NULL;
> +}
> +
> +static int poll_pidfd(const char *test_name, int pidfd)
> +{
> + int c;
> + int epoll_fd = epoll_create1(0);
A style point, but I find it's best not to do resource allocation in
variable declarations like this. It breaks up the usual pattern of:
ret = -ENOMEM;
resource = allocate();
if (allocation_failed(resource))
goto err;
...
out:
free(resource);
err:
return ret;
You're not closing this fd on every path (they all exit [for now :D]
so it's probably ok), but it might be nice to make this match a more
regular pattern.
> + struct epoll_event event, events[MAX_EVENTS];
> +
> + if (epoll_fd == -1)
> + ksft_exit_fail_msg("%s test: Failed to create epoll file
[PATCH RFC 2/2] Add selftests for pidfd polling
Other than verifying pidfd based polling, the tests make sure that
wait semantics are preserved with the pidfd poll. Notably the 2 cases:
1. If a thread group leader exits while threads still there, then no
pidfd poll notifcation should happen.
2. If a non-thread group leader does an execve, then the thread group
leader is signaled to exit and is replaced with the execing thread
as the new leader, however the parent is not notified in this case.
Signed-off-by: Joel Fernandes (Google)
---
tools/testing/selftests/pidfd/Makefile | 2 +-
tools/testing/selftests/pidfd/pidfd_test.c | 216 -
2 files changed, 208 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/pidfd/Makefile
b/tools/testing/selftests/pidfd/Makefile
index deaf8073bc06..4b31c14f273c 100644
--- a/tools/testing/selftests/pidfd/Makefile
+++ b/tools/testing/selftests/pidfd/Makefile
@@ -1,4 +1,4 @@
-CFLAGS += -g -I../../../../usr/include/
+CFLAGS += -g -I../../../../usr/include/ -lpthread
TEST_GEN_PROGS := pidfd_test
diff --git a/tools/testing/selftests/pidfd/pidfd_test.c
b/tools/testing/selftests/pidfd/pidfd_test.c
index d59378a93782..4d5206280091 100644
--- a/tools/testing/selftests/pidfd/pidfd_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_test.c
@@ -4,18 +4,26 @@
#include
#include
#include
+#include
#include
#include
#include
#include
#include
#include
+#include
+#include
#include
#include
+#include
#include
#include "../kselftest.h"
+#define CHILD_THREAD_MIN_WAIT 3 /* seconds */
+#define MAX_EVENTS 5
+#define __NR_pidfd_send_signal 424
+
static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
unsigned int flags)
{
@@ -30,6 +38,22 @@ static void set_signal_received_on_sigusr1(int sig)
signal_received = 1;
}
+static int open_pidfd(const char *test_name, pid_t pid)
+{
+ char buf[256];
+ int pidfd;
+
+ snprintf(buf, sizeof(buf), "/proc/%d", pid);
+ pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
+
+ if (pidfd < 0)
+ ksft_exit_fail_msg(
+ "%s test: Failed to open process file descriptor\n",
+ test_name);
+
+ return pidfd;
+}
+
/*
* Straightforward test to see whether pidfd_send_signal() works is to send
* a signal to ourself.
@@ -87,7 +111,6 @@ static int wait_for_pid(pid_t pid)
static int test_pidfd_send_signal_exited_fail(void)
{
int pidfd, ret, saved_errno;
- char buf[256];
pid_t pid;
const char *test_name = "pidfd_send_signal signal exited process";
@@ -99,17 +122,10 @@ static int test_pidfd_send_signal_exited_fail(void)
if (pid == 0)
_exit(EXIT_SUCCESS);
- snprintf(buf, sizeof(buf), "/proc/%d", pid);
-
- pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
+ pidfd = open_pidfd(test_name, pid);
(void)wait_for_pid(pid);
- if (pidfd < 0)
- ksft_exit_fail_msg(
- "%s test: Failed to open process file descriptor\n",
- test_name);
-
ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
saved_errno = errno;
close(pidfd);
@@ -368,10 +384,192 @@ static int test_pidfd_send_signal_syscall_support(void)
return 0;
}
+void *test_pidfd_poll_exec_thread(void *priv)
+{
+ char waittime[256];
+
+ ksft_print_msg("Child Thread: starting. pid %d tid %d ; and sleeping\n",
+ getpid(), syscall(SYS_gettid));
+ ksft_print_msg("Child Thread: doing exec of sleep\n");
+
+ sprintf(waittime, "%d", CHILD_THREAD_MIN_WAIT);
+ execl("/bin/sleep", "sleep", waittime, (char *)NULL);
+
+ ksft_print_msg("Child Thread: DONE. pid %d tid %d\n",
+ getpid(), syscall(SYS_gettid));
+ return NULL;
+}
+
+static int poll_pidfd(const char *test_name, int pidfd)
+{
+ int c;
+ int epoll_fd = epoll_create1(0);
+ struct epoll_event event, events[MAX_EVENTS];
+
+ if (epoll_fd == -1)
+ ksft_exit_fail_msg("%s test: Failed to create epoll file
descriptor\n",
+ test_name);
+
+ event.events = EPOLLIN;
+ event.data.fd = pidfd;
+
+ if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, pidfd, &event)) {
+ ksft_print_msg("%s test: Failed to add epoll file descriptor:
Skipping\n",
+ test_name);
+ _exit(PIDFD_SKIP);
+ }
+
+ c = epoll_wait(epoll_fd, events, MAX_EVENTS, 5000);
+ if (c != 1 || !(events[0].events & EPOLLIN))
+ ksft_exit_fail_msg("%s test: Unexpected epoll_wait result
(c=%d, events=%x)\n",
+ test_name, c, events[0].events);
+
+ close(epoll_fd);
+ return events[0].events;
+
+}
+
+int test_pidfd_poll_exec(int use_waitpid)
+{
+ int pid, pidfd;
+ int status, ret;
