Date: Fri, 28 Nov 2025 09:18:06 +0000 From: Dag-Erling=?utf-8?Q? Sm=C3=B8rg?=rav <des@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 330d4437f210 - main - bus: Add device_has_children predicate Message-ID: <692968ce.31fd6.26c4e4f2@gitrepo.freebsd.org>
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The branch main has been updated by des: URL: https://cgit.FreeBSD.org/src/commit/?id=330d4437f2100fc05e576763f4f6a7198080663a commit 330d4437f2100fc05e576763f4f6a7198080663a Author: Dag-Erling Smørgrav <des@FreeBSD.org> AuthorDate: 2025-11-28 09:14:31 +0000 Commit: Dag-Erling Smørgrav <des@FreeBSD.org> CommitDate: 2025-11-28 09:17:09 +0000 bus: Add device_has_children predicate Add a device_has_children() function which can be used to check if a device has children without allocating a list of them which we aren't going to use, or even counting them. Also modify device_get_children() so it can be used to query the count without allocating a list. MFC after: 1 week Sponsored by: Klara, Inc. Sponsored by: NetApp, Inc. Reviewed by: imp, markj Differential Revision: https://reviews.freebsd.org/D53918 --- share/man/man9/Makefile | 1 + share/man/man9/device_get_children.9 | 47 ++++++++++++++++++++++++++++++------ sys/kern/subr_bus.c | 18 ++++++++++++++ sys/sys/bus.h | 1 + 4 files changed, 59 insertions(+), 8 deletions(-) diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile index 22358e8d033a..ac5224b76444 100644 --- a/share/man/man9/Makefile +++ b/share/man/man9/Makefile @@ -1040,6 +1040,7 @@ MLINKS+=devfs_set_cdevpriv.9 devfs_clear_cdevpriv.9 \ MLINKS+=device_add_child.9 device_add_child_ordered.9 MLINKS+=device_enable.9 device_disable.9 \ device_enable.9 device_is_enabled.9 +MLINKS+=device_get_children.9 device_has_children.9 MLINKS+=device_get_ivars.9 device_set_ivars.9 MLINKS+=device_get_name.9 device_get_nameunit.9 MLINKS+=device_get_state.9 device_busy.9 \ diff --git a/share/man/man9/device_get_children.9 b/share/man/man9/device_get_children.9 index f9c36971e9b5..45f8f468531b 100644 --- a/share/man/man9/device_get_children.9 +++ b/share/man/man9/device_get_children.9 @@ -1,6 +1,7 @@ .\" -*- nroff -*- .\" .\" Copyright (c) 1998 Doug Rabson +.\" Copyright (c) 2025 Dag-Erling Smørgrav <des@FreeBSD.org> .\" .\" All rights reserved. .\" @@ -26,21 +27,27 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.Dd August 23, 2008 +.Dd November 28, 2025 .Dt DEVICE_GET_CHILDREN 9 .Os .Sh NAME -.Nm device_get_children -.Nd get a list of devices connected to a device +.Nm device_get_children , +.Nm device_has_children +.Nd examine devices connected to a device .Sh SYNOPSIS .In sys/param.h .In sys/bus.h .Ft int .Fn device_get_children "device_t dev" "device_t **devlistp" "int *devcountp" +.Ft bool +.Fn device_has_children "device_t dev" .Sh DESCRIPTION -Retrieve a list of all device instances currently connected to -.Pa dev -and return the list in +The +.Nm device_get_children +function retrieves a list of all device instances currently connected +to +.Fa dev . +It returns the list in .Fa *devlistp and the count in .Fa *devcountp . @@ -50,11 +57,35 @@ The memory allocated for the list should be freed using and .Fa devcountp are not changed when an error is returned. +.Pp +As a special case, if +.Fa devlistp +is null, no memory is allocated but the count is still returned in +.Fa *devcountp . +.Pp +The +.Nm device_has_children +function returns +.Dv true +if +.Fa dev +has at least one child and +.Dv false +if it has none. .Sh RETURN VALUES -Zero is returned on success, otherwise an appropriate error is returned. +The +.Nm device_get_children +function returns zero on success and an appropriate error otherwise. +The +.Nm device_has_children +function returns true if the specified device has at least one child +and false otherwise. .Sh SEE ALSO .Xr devclass 9 , .Xr device 9 .Sh AUTHORS +.An -nosplit This manual page was written by -.An Doug Rabson . +.An Doug Rabson Aq Mt dfr@FreeBSD.org +and +.An Dag-Erling Sm\(/orgrav Aq Mt des@FreeBSD.org . diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c index b84f69cfd03e..755d7d41899f 100644 --- a/sys/kern/subr_bus.c +++ b/sys/kern/subr_bus.c @@ -1858,6 +1858,10 @@ device_get_children(device_t dev, device_t **devlistp, int *devcountp) TAILQ_FOREACH(child, &dev->children, link) { count++; } + if (devlistp == NULL) { + *devcountp = count; + return (0); + } if (count == 0) { *devlistp = NULL; *devcountp = 0; @@ -1880,6 +1884,20 @@ device_get_children(device_t dev, device_t **devlistp, int *devcountp) return (0); } +/** + * @brief Check if a device has children + * + * @param dev the device to examine + * + * @rerval true the device has at least one child + * @retval false the device has no children + */ +bool +device_has_children(device_t dev) +{ + return (!TAILQ_EMPTY(&dev->children)); +} + /** * @brief Return the current driver for the device or @c NULL if there * is no driver currently attached diff --git a/sys/sys/bus.h b/sys/sys/bus.h index 4cc8091bf775..f54ed2c58fd1 100644 --- a/sys/sys/bus.h +++ b/sys/sys/bus.h @@ -713,6 +713,7 @@ device_state_t device_get_state(device_t dev); int device_get_unit(device_t dev); struct sysctl_ctx_list *device_get_sysctl_ctx(device_t dev); struct sysctl_oid *device_get_sysctl_tree(device_t dev); +bool device_has_children(device_t dev); int device_has_quiet_children(device_t dev); int device_is_alive(device_t dev); /* did probe succeed? */ int device_is_attached(device_t dev); /* did attach succeed? */help
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