[PATCH] shared/fdset: add detailed debug logging to fdset_new_fill()

[PATCH] shared/fdset: add detailed debug logging to fdset_new_fill()

[Ashish Kumar Mishra]

From: AshishKumar Mishra <ashishkumar.mishra@bmwtechworks.in>

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>
---
 ...-detailed-debug-logging-to-fdset_new.patch | 97 +++++++++++++++++++
 meta/recipes-core/systemd/systemd_258.1.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_258.1.bb b/meta/recipes-core/systemd/systemd_258.1.bb
index fdf4dc5bdc..0259bacb37 100644
--- a/meta/recipes-core/systemd/systemd_258.1.bb
+++ b/meta/recipes-core/systemd/systemd_258.1.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 \
            "
 
 # patches needed by musl
-- 
2.34.1

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

[AshishKumar Mishra]

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Hi Team,

Any input on this patch
I have backported this patch which i have merged in systemd upstream code base
I could not see this patch in master-next branch of openembedded-core - OpenEmbedded Core layer ( https://git.openembedded.org/openembedded-core/log/?h=master-next )
Hence wanted to check if there is any feedback from team

Thanks .
Ashish

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

[Mathieu Dubois-Briand]

On Mon Mar 9, 2026 at 5:30 AM CET, AshishKumar Mishra via lists.openembedded.org wrote:
> Hi Team,
>
> Any input on this patch
> I have backported this patch which i have merged in systemd upstream code base
> I could not see this patch in master-next branch of openembedded-core - OpenEmbedded Core layer ( https://git.openembedded.org/openembedded-core/log/?h=master-next )
> Hence wanted to check if there is any feedback from team
>
> Thanks .
> Ashish

Hi Ashish,

Yes, I had your patch aside for a few days, as a systemd upgrade to
259.1/259.3 was already sent and conflicting with your patch. This
upgrade is now merged.

Is your patch still needed with systemd 259.3? If that's the case, can
you please rebase on top of master?

Thanks,
Mathieu

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[PATCH] shared/fdset: add detailed debug logging to fdset_new_fill()

[Ashish Kumar Mishra]

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>
---
 ...-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 = " \
-- 
2.34.1

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

[AshishKumar Mishra]

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Hi Mathiew ,

Thanks for sharing the details.
Have rebased the patch to latest version of systemd in yocto
https://lists.openembedded.org/g/openembedded-core/message/232763

Can you please consider this for merging on master branch

Thanks,
Ashish

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

[Ashish Mishra]

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Hi Team,

As suggested earlier , have already rebased to latest systemd code base
Does team have any suggestion on https://lists.openembedded.org/g/openembedded-core/message/232763
I still don't see in master-next branch

Thanks ,
Ashish

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

[Yoann Congal]

qn Thu Mar 12, 2026 at 8:33 AM CET, Ashish Mishra via lists.openembedded.org wrote:
> Hi Team,
>
> As suggested earlier , have already rebased to latest systemd code base
> Does team have any suggestion on https://lists.openembedded.org/g/openembedded-core/message/232763
> I still don't see in master-next branch

Your patch is now in mathieu/master-next-success[0], which mean it has
succesfully passed test on the autobuilder. It will now go through
review, but, as stated in the weekly status[1], the review team has
limited bandwidth. So, please be patient. I'd suggest waiting at least a
week before pinging a patch.
[0]: https://git.openembedded.org/openembedded-core-contrib/log/?h=mathieu/master-next-success
[1]: https://wiki.yoctoproject.org/wiki/2026_Yocto_Project_Weekly_Status_Archive#Yocto_Project_Status_10_March_2026
>
> Thanks ,
> Ashish


-- 
Yoann Congal
Smile ECS

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

[Ashish Mishra]

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Thanks for feedback Yoann
Will reshare by adding the changelog

Thanks,
Ashish

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

[Ashish Mishra]

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Hi Mathieu / Yoann/ Peter ,

Thanks for feedback.

Have shared the updated patch with suggested changes at
https://lists.openembedded.org/g/openembedded-core/topic/patch_v3_systemd_add/118379596

Can team please consider this for master branch
openembedded-core@lists.openembedded.org | [PATCH v3] systemd: add detailed debug logging to fdset_new_fill() ( https://lists.openembedded.org/g/openembedded-core/topic/patch_v3_systemd_add/118379596 )

Thanks,
Ashish

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