Re: [OE-core] [PATCH] shared/fdset: add detailed debug logging to fdset_new_fill()

["Yoann Congal" <yoann.congal@smile.fr>]

On Tue Mar 10, 2026 at 9:09 AM CET, Ashish Kumar Mishra via lists.openembedded.org wrote:
> Currently, when fdset_new_fill() fails to open /proc/self/fd or
> encounters an error while processing individual file descriptors
> (such as fcntl or fstat failures), it returns a silent error code.
>
> For debugging rarely reproducible failures it becomes difficult to
> know the exact cause of failure
> This commit updates the function to use log_debug_errno() for all
> error paths and hence  provides better visibility into why FD collection
> failed, including the path of the problematic FD (via fd_get_path)
> and its inode type.
>
> Upstream-Status: Backport [https://github.com/systemd/systemd/pull/40385]
>
> Signed-off-by: AshishKumar Mishra <ashishkumar.mishra@bmwtechworks.in>
> ---

Hello,

This is the second version of this patch. Please see [0] for how to mark
it as such and handle patches iterations (Note the patch changelog below
the "---" line). This will make the reviews a lot easier and less
confusing for reviewers.

Regards,

[0]: https://docs.yoctoproject.org/contributor-guide/submit-changes.html#taking-patch-review-into-account

>  ...-detailed-debug-logging-to-fdset_new.patch | 97 +++++++++++++++++++
>  meta/recipes-core/systemd/systemd_259.3.bb    |  1 +
>  2 files changed, 98 insertions(+)
>  create mode 100644 meta/recipes-core/systemd/systemd/0018-shared-fdset-add-detailed-debug-logging-to-fdset_new.patch
>
> diff --git a/meta/recipes-core/systemd/systemd/0018-shared-fdset-add-detailed-debug-logging-to-fdset_new.patch b/meta/recipes-core/systemd/systemd/0018-shared-fdset-add-detailed-debug-logging-to-fdset_new.patch
> new file mode 100644
> index 0000000000..849f5cfda1
> --- /dev/null
> +++ b/meta/recipes-core/systemd/systemd/0018-shared-fdset-add-detailed-debug-logging-to-fdset_new.patch
> @@ -0,0 +1,97 @@
> +From 0565f9f27323a8f9e62d85f2add542af99cea06a Mon Sep 17 00:00:00 2001
> +From: AshishKumar Mishra <ashishkumar.mishra@bmwtechworks.in>
> +Date: Wed, 21 Jan 2026 14:13:29 +0530
> +Subject: [PATCH] shared/fdset: add detailed debug logging to fdset_new_fill()
> +
> +Currently, when fdset_new_fill() fails to open /proc/self/fd or
> +encounters an error while processing individual file descriptors
> +(such as fcntl or fstat failures), it returns a silent error code.
> +
> +For debugging rarely reproducible failures it becomes difficult to
> +know the exact cause of failure
> +This commit updates the function to use log_debug_errno() for all
> +error paths and hence  provides better visibility into why FD collection
> +failed, including the path of the problematic FD (via fd_get_path)
> +and its inode type.
> +
> +Upstream-Status: Backport [https://github.com/systemd/systemd/pull/40385]
> +
> +Signed-off-by: AshishKumar Mishra <ashishkumar.mishra@bmwtechworks.in>
> +---
> + src/shared/fdset.c | 35 ++++++++++++++++++++++++++---------
> + 1 file changed, 26 insertions(+), 9 deletions(-)
> +
> +diff --git a/src/shared/fdset.c b/src/shared/fdset.c
> +index 832e7fda60..f340f41b0e 100644
> +--- a/src/shared/fdset.c
> ++++ b/src/shared/fdset.c
> +@@ -8,6 +8,7 @@
> + #include "alloc-util.h"
> + #include "async.h"
> + #include "dirent-util.h"
> ++#include "errno-util.h"
> + #include "fd-util.h"
> + #include "fdset.h"
> + #include "log.h"
> +@@ -179,9 +180,10 @@ int fdset_new_fill(
> +         d = opendir("/proc/self/fd");
> +         if (!d) {
> +                 if (errno == ENOENT && proc_mounted() == 0)
> +-                        return -ENOSYS;
> ++                        return log_debug_errno(SYNTHETIC_ERRNO(ENOSYS),
> ++                                               "Failed to open /proc/self/fd/, /proc/ is not mounted.");
> + 
> +-                return -errno;
> ++                return log_debug_errno(errno, "Failed to open /proc/self/fd/: %m ");
> +         }
> + 
> +         s = fdset_new();
> +@@ -210,9 +212,14 @@ int fdset_new_fill(
> +                          * been passed in can be collected and fds which have been created locally can be
> +                          * ignored, under the assumption that only the latter have O_CLOEXEC set. */
> + 
> +-                        fl = fcntl(fd, F_GETFD);
> +-                        if (fl < 0)
> +-                                return -errno;
> ++                        fl = RET_NERRNO(fcntl(fd, F_GETFD));
> ++                        if (fl < 0) {
> ++                                _cleanup_free_ char *path = NULL;
> ++                                (void) fd_get_path(fd, &path);
> ++                                return log_debug_errno(fl,
> ++                                                       "Failed to get flag of fd=%d (%s): %m ",
> ++                                                       fd, strna(path));
> ++                        }
> + 
> +                         if (FLAGS_SET(fl, FD_CLOEXEC) != !!filter_cloexec)
> +                                 continue;
> +@@ -221,13 +228,23 @@ int fdset_new_fill(
> +                 /* We need to set CLOEXEC manually only if we're collecting non-CLOEXEC fds. */
> +                 if (filter_cloexec <= 0) {
> +                         r = fd_cloexec(fd, true);
> +-                        if (r < 0)
> +-                                return r;
> ++                        if (r < 0) {
> ++                                _cleanup_free_ char *path = NULL;
> ++                                (void) fd_get_path(fd, &path);
> ++                                return log_debug_errno(r,
> ++                                                       "Failed to set CLOEXEC flag fd=%d (%s): %m ",
> ++                                                       fd, strna(path));
> ++                        }
> +                 }
> + 
> +                 r = fdset_put(s, fd);
> +-                if (r < 0)
> +-                        return r;
> ++                if (r < 0) {
> ++                        _cleanup_free_ char *path = NULL;
> ++                        (void) fd_get_path(fd, &path);
> ++                        return log_debug_errno(r,
> ++                                               "Failed to put fd=%d (%s) into fdset: %m ",
> ++                                               fd, strna(path));
> ++                }
> +         }
> + 
> +         *ret = TAKE_PTR(s);
> +-- 
> +2.34.1
> +
> diff --git a/meta/recipes-core/systemd/systemd_259.3.bb b/meta/recipes-core/systemd/systemd_259.3.bb
> index bcb8fe3d9c..44d319d0c5 100644
> --- a/meta/recipes-core/systemd/systemd_259.3.bb
> +++ b/meta/recipes-core/systemd/systemd_259.3.bb
> @@ -33,6 +33,7 @@ SRC_URI += " \
>             file://0001-binfmt-Don-t-install-dependency-links-at-install-tim.patch \
>             file://0002-implment-systemd-sysv-install-for-OE.patch \
>             file://0003-Do-not-create-var-log-README.patch \
> +           file://0018-shared-fdset-add-detailed-debug-logging-to-fdset_new.patch \
>             "
>  
>  PAM_PLUGINS = " \


-- 
Yoann Congal
Smile ECS