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Message-Id: <20251028-work-coredump-signal-v1-17-ca449b7b7aa0@kernel.org>
Date: Tue, 28 Oct 2025 09:46:02 +0100
From: Christian Brauner <brauner@...nel.org>
To: linux-fsdevel@...r.kernel.org
Cc: Oleg Nesterov <oleg@...hat.com>, Amir Goldstein <amir73il@...il.com>,
Aleksa Sarai <cyphar@...har.com>,
Yu Watanabe <watanabe.yu+github@...il.com>,
Josef Bacik <josef@...icpanda.com>, Jeff Layton <jlayton@...nel.org>,
Jann Horn <jannh@...gle.com>, Luca Boccassi <luca.boccassi@...il.com>,
Alexander Mikhalitsyn <alexander@...alicyn.com>,
linux-kernel@...r.kernel.org, Alexander Viro <viro@...iv.linux.org.uk>,
Jan Kara <jack@...e.cz>, Lennart Poettering <lennart@...ttering.net>,
Mike Yuan <me@...dnzj.com>,
Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>,
Christian Brauner <brauner@...nel.org>
Subject: [PATCH 17/22] selftests/coredump: add debug logging to test
helpers
so we can easily figure out why something failed.
Signed-off-by: Christian Brauner <brauner@...nel.org>
---
.../selftests/coredump/coredump_test_helpers.c | 55 +++++++++++++++++-----
1 file changed, 44 insertions(+), 11 deletions(-)
diff --git a/tools/testing/selftests/coredump/coredump_test_helpers.c b/tools/testing/selftests/coredump/coredump_test_helpers.c
index 116c797090a1..65deb3cfbe1b 100644
--- a/tools/testing/selftests/coredump/coredump_test_helpers.c
+++ b/tools/testing/selftests/coredump/coredump_test_helpers.c
@@ -131,17 +131,26 @@ int get_peer_pidfd(int fd)
int ret = getsockopt(fd, SOL_SOCKET, SO_PEERPIDFD, &fd_peer_pidfd,
&fd_peer_pidfd_len);
if (ret < 0) {
- fprintf(stderr, "%m - Failed to retrieve peer pidfd for coredump socket connection\n");
+ fprintf(stderr, "get_peer_pidfd: getsockopt(SO_PEERPIDFD) failed: %m\n");
return -1;
}
+ fprintf(stderr, "get_peer_pidfd: successfully retrieved pidfd %d\n", fd_peer_pidfd);
return fd_peer_pidfd;
}
bool get_pidfd_info(int fd_peer_pidfd, struct pidfd_info *info)
{
+ int ret;
memset(info, 0, sizeof(*info));
info->mask = PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP | PIDFD_INFO_COREDUMP_SIGNAL;
- return ioctl(fd_peer_pidfd, PIDFD_GET_INFO, info) == 0;
+ ret = ioctl(fd_peer_pidfd, PIDFD_GET_INFO, info);
+ if (ret < 0) {
+ fprintf(stderr, "get_pidfd_info: ioctl(PIDFD_GET_INFO) failed: %m\n");
+ return false;
+ }
+ fprintf(stderr, "get_pidfd_info: mask=0x%llx, coredump_mask=0x%x, coredump_signal=%d\n",
+ (unsigned long long)info->mask, info->coredump_mask, info->coredump_signal);
+ return true;
}
/* Protocol helper functions */
@@ -198,14 +207,23 @@ bool read_coredump_req(int fd, struct coredump_req *req)
/* Peek the size of the coredump request. */
ret = recv(fd, req, field_size, MSG_PEEK | MSG_WAITALL);
- if (ret != field_size)
+ if (ret != field_size) {
+ fprintf(stderr, "read_coredump_req: peek failed (got %zd, expected %zu): %m\n",
+ ret, field_size);
return false;
+ }
kernel_size = req->size;
- if (kernel_size < COREDUMP_ACK_SIZE_VER0)
+ if (kernel_size < COREDUMP_ACK_SIZE_VER0) {
+ fprintf(stderr, "read_coredump_req: kernel_size %zu < min %d\n",
+ kernel_size, COREDUMP_ACK_SIZE_VER0);
return false;
- if (kernel_size >= PAGE_SIZE)
+ }
+ if (kernel_size >= PAGE_SIZE) {
+ fprintf(stderr, "read_coredump_req: kernel_size %zu >= PAGE_SIZE %d\n",
+ kernel_size, PAGE_SIZE);
return false;
+ }
/* Use the minimum of user and kernel size to read the full request. */
user_size = sizeof(struct coredump_req);
@@ -295,25 +313,35 @@ void process_coredump_worker(int fd_coredump, int fd_peer_pidfd, int fd_core_fil
/* Set socket to non-blocking mode for edge-triggered epoll */
flags = fcntl(fd_coredump, F_GETFL, 0);
- if (flags < 0)
+ if (flags < 0) {
+ fprintf(stderr, "Worker: fcntl(F_GETFL) failed: %m\n");
goto out;
- if (fcntl(fd_coredump, F_SETFL, flags | O_NONBLOCK) < 0)
+ }
+ if (fcntl(fd_coredump, F_SETFL, flags | O_NONBLOCK) < 0) {
+ fprintf(stderr, "Worker: fcntl(F_SETFL, O_NONBLOCK) failed: %m\n");
goto out;
+ }
epfd = epoll_create1(0);
- if (epfd < 0)
+ if (epfd < 0) {
+ fprintf(stderr, "Worker: epoll_create1() failed: %m\n");
goto out;
+ }
ev.events = EPOLLIN | EPOLLRDHUP | EPOLLET;
ev.data.fd = fd_coredump;
- if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd_coredump, &ev) < 0)
+ if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd_coredump, &ev) < 0) {
+ fprintf(stderr, "Worker: epoll_ctl(EPOLL_CTL_ADD) failed: %m\n");
goto out;
+ }
for (;;) {
struct epoll_event events[1];
int n = epoll_wait(epfd, events, 1, -1);
- if (n < 0)
+ if (n < 0) {
+ fprintf(stderr, "Worker: epoll_wait() failed: %m\n");
break;
+ }
if (events[0].events & (EPOLLIN | EPOLLRDHUP)) {
for (;;) {
@@ -322,19 +350,24 @@ void process_coredump_worker(int fd_coredump, int fd_peer_pidfd, int fd_core_fil
if (bytes_read < 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK)
break;
+ fprintf(stderr, "Worker: read() failed: %m\n");
goto out;
}
if (bytes_read == 0)
goto done;
ssize_t bytes_write = write(fd_core_file, buffer, bytes_read);
- if (bytes_write != bytes_read)
+ if (bytes_write != bytes_read) {
+ fprintf(stderr, "Worker: write() failed (read=%zd, write=%zd): %m\n",
+ bytes_read, bytes_write);
goto out;
+ }
}
}
}
done:
exit_code = EXIT_SUCCESS;
+ fprintf(stderr, "Worker: completed successfully\n");
out:
if (epfd >= 0)
close(epfd);
--
2.47.3
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