76b61ebf1b
There's a failure case where an application gets a cqe entry, but
the kernel can then overwrite it before the application is done
reading it. This can happen since the io_uring_{get,wait}_completion()
interface both returns a CQE pointer AND increments the ring index.
If the kernel reuses this entry before the applications is done reading
it, the contents may be corrupted.
Remove the CQ head increment from the CQE retrieval, and put it into
a separate helper, io_uring_cqe_seen(). The application must call this
helper when it got a new CQE entry through one of the above calls, and
it's now done reading it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
107 lines
1.9 KiB
C
107 lines
1.9 KiB
C
/*
|
|
* Description: test io_uring poll handling
|
|
*
|
|
*/
|
|
#include <errno.h>
|
|
#include <stdio.h>
|
|
#include <unistd.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <signal.h>
|
|
#include <sys/poll.h>
|
|
#include <sys/wait.h>
|
|
|
|
#include "../src/liburing.h"
|
|
|
|
static void sig_alrm(int sig)
|
|
{
|
|
printf("Timed out!\n");
|
|
exit(1);
|
|
}
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
struct io_uring_cqe *cqe;
|
|
struct io_uring_sqe *sqe;
|
|
struct io_uring ring;
|
|
int pipe1[2];
|
|
pid_t p;
|
|
int ret;
|
|
|
|
if (pipe(pipe1) != 0) {
|
|
printf("pipe failed\n");
|
|
return 1;
|
|
}
|
|
|
|
p = fork();
|
|
switch (p) {
|
|
case -1:
|
|
printf("fork failed\n");
|
|
exit(2);
|
|
case 0: {
|
|
struct sigaction act;
|
|
|
|
ret = io_uring_queue_init(1, &ring, 0);
|
|
if (ret) {
|
|
printf("child: ring setup failed\n");
|
|
return 1;
|
|
}
|
|
|
|
memset(&act, 0, sizeof(act));
|
|
act.sa_handler = sig_alrm;
|
|
act.sa_flags = SA_RESTART;
|
|
sigaction(SIGALRM, &act, NULL);
|
|
alarm(1);
|
|
|
|
sqe = io_uring_get_sqe(&ring);
|
|
if (!sqe) {
|
|
printf("child: get sqe failed\n");
|
|
return 1;
|
|
}
|
|
|
|
io_uring_prep_poll_add(sqe, pipe1[0], POLLIN);
|
|
io_uring_sqe_set_data(sqe, sqe);
|
|
|
|
ret = io_uring_submit(&ring);
|
|
if (ret <= 0) {
|
|
printf("child: sqe submit failed\n");
|
|
return 1;
|
|
}
|
|
|
|
do {
|
|
ret = io_uring_wait_completion(&ring, &cqe);
|
|
if (ret < 0) {
|
|
printf("child: wait completion %d\n", ret);
|
|
break;
|
|
}
|
|
io_uring_cqe_seen(&ring, cqe);
|
|
} while (ret != 0);
|
|
|
|
if (ret < 0) {
|
|
printf("child: completion get failed\n");
|
|
return 1;
|
|
}
|
|
if (cqe->user_data != (unsigned long) sqe) {
|
|
printf("child: cqe doesn't match sqe\n");
|
|
return 1;
|
|
}
|
|
if ((cqe->res & POLLIN) != POLLIN) {
|
|
printf("child: bad return value %ld\n", (long) cqe->res);
|
|
return 1;
|
|
}
|
|
exit(0);
|
|
}
|
|
default:
|
|
do {
|
|
errno = 0;
|
|
ret = write(pipe1[1], "foo", 3);
|
|
} while (ret == -1 && errno == EINTR);
|
|
|
|
if (ret != 3) {
|
|
printf("parent: bad write return %d\n", ret);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
}
|