[1/6] sysfs: Introduce a mechanism to hide static attribute_groups
Commit Message
From: Dan Williams <dan.j.williams@intel.com>
Add a mechanism for named attribute_groups to hide their directory at
sysfs_update_group() time, or otherwise skip emitting the group
directory when the group is first registered. It piggybacks on
is_visible() in a similar manner as SYSFS_PREALLOC, i.e. special flags
in the upper bits of the returned mode. To use it, specify a symbol
prefix to DEFINE_SYSFS_GROUP_VISIBLE(), and then pass that same prefix
to SYSFS_GROUP_VISIBLE() when assigning the @is_visible() callback:
DEFINE_SYSFS_GROUP_VISIBLE($prefix)
struct attribute_group $prefix_group = {
.name = $name,
.is_visible = SYSFS_GROUP_VISIBLE($prefix),
};
SYSFS_GROUP_VISIBLE() expects a definition of $prefix_group_visible()
and $prefix_attr_visible(), where $prefix_group_visible() just returns
true / false and $prefix_attr_visible() behaves as normal.
The motivation for this capability is to centralize PCI device
authentication in the PCI core with a named sysfs group while keeping
that group hidden for devices and platforms that do not meet the
requirements. In a PCI topology, most devices will not support
authentication, a small subset will support just PCI CMA (Component
Measurement and Authentication), a smaller subset will support PCI CMA +
PCIe IDE (Link Integrity and Encryption), and only next generation
server hosts will start to include a platform TSM (TEE Security
Manager).
Without this capability the alternatives are:
* Check if all attributes are invisible and if so, hide the directory.
Beyond trouble getting this to work [1], this is an ABI change for
scenarios if userspace happens to depend on group visibility absent any
attributes. I.e. this new capability avoids regression since it does
not retroactively apply to existing cases.
* Publish an empty /sys/bus/pci/devices/$pdev/tsm/ directory for all PCI
devices (i.e. for the case when TSM platform support is present, but
device support is absent). Unfortunate that this will be a vestigial
empty directory in the vast majority of cases.
* Reintroduce usage of runtime calls to sysfs_{create,remove}_group()
in the PCI core. Bjorn has already indicated that he does not want to
see any growth of pci_sysfs_init() [2].
* Drop the named group and simulate a directory by prefixing all
TSM-related attributes with "tsm_". Unfortunate to not use the naming
capability of a sysfs group as intended.
In comparison, there is a small potential for regression if for some
reason an @is_visible() callback had dependencies on how many times it
was called. Additionally, it is no longer an error to update a group
that does not have its directory already present, and it is no longer a
WARN() to remove a group that was never visible.
Link: https://lore.kernel.org/all/2024012321-envious-procedure-4a58@gregkh/ [1]
Link: https://lore.kernel.org/linux-pci/20231019200110.GA1410324@bhelgaas/ [2]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/sysfs/group.c | 45 ++++++++++++++++++++++++-------
include/linux/sysfs.h | 63 ++++++++++++++++++++++++++++++++++---------
2 files changed, 87 insertions(+), 21 deletions(-)
Comments
On 1/30/24 19:46, Greg Kroah-Hartman wrote:
> From: Dan Williams <dan.j.williams@intel.com>
>
> Add a mechanism for named attribute_groups to hide their directory at
> sysfs_update_group() time, or otherwise skip emitting the group
> directory when the group is first registered. It piggybacks on
> is_visible() in a similar manner as SYSFS_PREALLOC, i.e. special flags
> in the upper bits of the returned mode. To use it, specify a symbol
> prefix to DEFINE_SYSFS_GROUP_VISIBLE(), and then pass that same prefix
> to SYSFS_GROUP_VISIBLE() when assigning the @is_visible() callback:
>
> DEFINE_SYSFS_GROUP_VISIBLE($prefix)
>
> struct attribute_group $prefix_group = {
> .name = $name,
> .is_visible = SYSFS_GROUP_VISIBLE($prefix),
> };
>
> SYSFS_GROUP_VISIBLE() expects a definition of $prefix_group_visible()
> and $prefix_attr_visible(), where $prefix_group_visible() just returns
> true / false and $prefix_attr_visible() behaves as normal.
>
> The motivation for this capability is to centralize PCI device
> authentication in the PCI core with a named sysfs group while keeping
> that group hidden for devices and platforms that do not meet the
> requirements. In a PCI topology, most devices will not support
> authentication, a small subset will support just PCI CMA (Component
> Measurement and Authentication), a smaller subset will support PCI CMA +
> PCIe IDE (Link Integrity and Encryption), and only next generation
> server hosts will start to include a platform TSM (TEE Security
> Manager).
>
> Without this capability the alternatives are:
>
> * Check if all attributes are invisible and if so, hide the directory.
> Beyond trouble getting this to work [1], this is an ABI change for
> scenarios if userspace happens to depend on group visibility absent any
> attributes. I.e. this new capability avoids regression since it does
> not retroactively apply to existing cases.
>
> * Publish an empty /sys/bus/pci/devices/$pdev/tsm/ directory for all PCI
> devices (i.e. for the case when TSM platform support is present, but
> device support is absent). Unfortunate that this will be a vestigial
> empty directory in the vast majority of cases.
>
> * Reintroduce usage of runtime calls to sysfs_{create,remove}_group()
> in the PCI core. Bjorn has already indicated that he does not want to
> see any growth of pci_sysfs_init() [2].
>
> * Drop the named group and simulate a directory by prefixing all
> TSM-related attributes with "tsm_". Unfortunate to not use the naming
> capability of a sysfs group as intended.
>
> In comparison, there is a small potential for regression if for some
> reason an @is_visible() callback had dependencies on how many times it
> was called. Additionally, it is no longer an error to update a group
> that does not have its directory already present, and it is no longer a
> WARN() to remove a group that was never visible.
>
> Link: https://lore.kernel.org/all/2024012321-envious-procedure-4a58@gregkh/ [1]
> Link: https://lore.kernel.org/linux-pci/20231019200110.GA1410324@bhelgaas/ [2]
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch seems to introduce a regression on our Lunar Lake test
devices, where we can't boot to an ssh shell. No issues on older devices
[1]. Bard Liao and I reproduced the same results on different boards.
We'll need to find someone with direct device access to provide more
information on the problem, remote testing without ssh is a
self-negating proposition.
Is there a dependency on other patches? Our tests are still based on
6.7.0-rc3 due to other upstream issues we're currently working through.
[1] https://github.com/thesofproject/linux/pull/4799
On Wed, Jan 31, 2024 at 02:05:04PM +0100, Pierre-Louis Bossart wrote:
>
>
> On 1/30/24 19:46, Greg Kroah-Hartman wrote:
> > From: Dan Williams <dan.j.williams@intel.com>
> >
> > Add a mechanism for named attribute_groups to hide their directory at
> > sysfs_update_group() time, or otherwise skip emitting the group
> > directory when the group is first registered. It piggybacks on
> > is_visible() in a similar manner as SYSFS_PREALLOC, i.e. special flags
> > in the upper bits of the returned mode. To use it, specify a symbol
> > prefix to DEFINE_SYSFS_GROUP_VISIBLE(), and then pass that same prefix
> > to SYSFS_GROUP_VISIBLE() when assigning the @is_visible() callback:
> >
> > DEFINE_SYSFS_GROUP_VISIBLE($prefix)
> >
> > struct attribute_group $prefix_group = {
> > .name = $name,
> > .is_visible = SYSFS_GROUP_VISIBLE($prefix),
> > };
> >
> > SYSFS_GROUP_VISIBLE() expects a definition of $prefix_group_visible()
> > and $prefix_attr_visible(), where $prefix_group_visible() just returns
> > true / false and $prefix_attr_visible() behaves as normal.
> >
> > The motivation for this capability is to centralize PCI device
> > authentication in the PCI core with a named sysfs group while keeping
> > that group hidden for devices and platforms that do not meet the
> > requirements. In a PCI topology, most devices will not support
> > authentication, a small subset will support just PCI CMA (Component
> > Measurement and Authentication), a smaller subset will support PCI CMA +
> > PCIe IDE (Link Integrity and Encryption), and only next generation
> > server hosts will start to include a platform TSM (TEE Security
> > Manager).
> >
> > Without this capability the alternatives are:
> >
> > * Check if all attributes are invisible and if so, hide the directory.
> > Beyond trouble getting this to work [1], this is an ABI change for
> > scenarios if userspace happens to depend on group visibility absent any
> > attributes. I.e. this new capability avoids regression since it does
> > not retroactively apply to existing cases.
> >
> > * Publish an empty /sys/bus/pci/devices/$pdev/tsm/ directory for all PCI
> > devices (i.e. for the case when TSM platform support is present, but
> > device support is absent). Unfortunate that this will be a vestigial
> > empty directory in the vast majority of cases.
> >
> > * Reintroduce usage of runtime calls to sysfs_{create,remove}_group()
> > in the PCI core. Bjorn has already indicated that he does not want to
> > see any growth of pci_sysfs_init() [2].
> >
> > * Drop the named group and simulate a directory by prefixing all
> > TSM-related attributes with "tsm_". Unfortunate to not use the naming
> > capability of a sysfs group as intended.
> >
> > In comparison, there is a small potential for regression if for some
> > reason an @is_visible() callback had dependencies on how many times it
> > was called. Additionally, it is no longer an error to update a group
> > that does not have its directory already present, and it is no longer a
> > WARN() to remove a group that was never visible.
> >
> > Link: https://lore.kernel.org/all/2024012321-envious-procedure-4a58@gregkh/ [1]
> > Link: https://lore.kernel.org/linux-pci/20231019200110.GA1410324@bhelgaas/ [2]
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> This patch seems to introduce a regression on our Lunar Lake test
> devices, where we can't boot to an ssh shell. No issues on older devices
> [1]. Bard Liao and I reproduced the same results on different boards.
>
> We'll need to find someone with direct device access to provide more
> information on the problem, remote testing without ssh is a
> self-negating proposition.
>
> Is there a dependency on other patches? Our tests are still based on
> 6.7.0-rc3 due to other upstream issues we're currently working through.
This should be totally stand-alone and not cause any problems,
especially if you don't have any other patches applied.
I did make this against 6.8-rc2, perhaps that's the issue?
thanks,
greg k-h
Pierre-Louis Bossart wrote:
>
>
> On 1/30/24 19:46, Greg Kroah-Hartman wrote:
> > From: Dan Williams <dan.j.williams@intel.com>
> >
> > Add a mechanism for named attribute_groups to hide their directory at
> > sysfs_update_group() time, or otherwise skip emitting the group
> > directory when the group is first registered. It piggybacks on
> > is_visible() in a similar manner as SYSFS_PREALLOC, i.e. special flags
> > in the upper bits of the returned mode. To use it, specify a symbol
> > prefix to DEFINE_SYSFS_GROUP_VISIBLE(), and then pass that same prefix
> > to SYSFS_GROUP_VISIBLE() when assigning the @is_visible() callback:
> >
> > DEFINE_SYSFS_GROUP_VISIBLE($prefix)
> >
> > struct attribute_group $prefix_group = {
> > .name = $name,
> > .is_visible = SYSFS_GROUP_VISIBLE($prefix),
> > };
> >
> > SYSFS_GROUP_VISIBLE() expects a definition of $prefix_group_visible()
> > and $prefix_attr_visible(), where $prefix_group_visible() just returns
> > true / false and $prefix_attr_visible() behaves as normal.
> >
> > The motivation for this capability is to centralize PCI device
> > authentication in the PCI core with a named sysfs group while keeping
> > that group hidden for devices and platforms that do not meet the
> > requirements. In a PCI topology, most devices will not support
> > authentication, a small subset will support just PCI CMA (Component
> > Measurement and Authentication), a smaller subset will support PCI CMA +
> > PCIe IDE (Link Integrity and Encryption), and only next generation
> > server hosts will start to include a platform TSM (TEE Security
> > Manager).
> >
> > Without this capability the alternatives are:
> >
> > * Check if all attributes are invisible and if so, hide the directory.
> > Beyond trouble getting this to work [1], this is an ABI change for
> > scenarios if userspace happens to depend on group visibility absent any
> > attributes. I.e. this new capability avoids regression since it does
> > not retroactively apply to existing cases.
> >
> > * Publish an empty /sys/bus/pci/devices/$pdev/tsm/ directory for all PCI
> > devices (i.e. for the case when TSM platform support is present, but
> > device support is absent). Unfortunate that this will be a vestigial
> > empty directory in the vast majority of cases.
> >
> > * Reintroduce usage of runtime calls to sysfs_{create,remove}_group()
> > in the PCI core. Bjorn has already indicated that he does not want to
> > see any growth of pci_sysfs_init() [2].
> >
> > * Drop the named group and simulate a directory by prefixing all
> > TSM-related attributes with "tsm_". Unfortunate to not use the naming
> > capability of a sysfs group as intended.
> >
> > In comparison, there is a small potential for regression if for some
> > reason an @is_visible() callback had dependencies on how many times it
> > was called. Additionally, it is no longer an error to update a group
> > that does not have its directory already present, and it is no longer a
> > WARN() to remove a group that was never visible.
> >
> > Link: https://lore.kernel.org/all/2024012321-envious-procedure-4a58@gregkh/ [1]
> > Link: https://lore.kernel.org/linux-pci/20231019200110.GA1410324@bhelgaas/ [2]
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> This patch seems to introduce a regression on our Lunar Lake test
> devices, where we can't boot to an ssh shell. No issues on older devices
> [1]. Bard Liao and I reproduced the same results on different boards.
>
> We'll need to find someone with direct device access to provide more
> information on the problem, remote testing without ssh is a
> self-negating proposition.
>
> Is there a dependency on other patches? Our tests are still based on
> 6.7.0-rc3 due to other upstream issues we're currently working through.
The only behavior change I can imagine with this patch is that
->is_visble() callbacks get called extra times for named attribute
groups.
..or if an is_visible() callback was inadvertantly already using the
SYSFS_GROUP_INVISIBLE flag in umode_t result.
Dan Williams wrote:
> Pierre-Louis Bossart wrote:
> >
> >
> > On 1/30/24 19:46, Greg Kroah-Hartman wrote:
> > > From: Dan Williams <dan.j.williams@intel.com>
> > >
> > > Add a mechanism for named attribute_groups to hide their directory at
> > > sysfs_update_group() time, or otherwise skip emitting the group
> > > directory when the group is first registered. It piggybacks on
> > > is_visible() in a similar manner as SYSFS_PREALLOC, i.e. special flags
> > > in the upper bits of the returned mode. To use it, specify a symbol
> > > prefix to DEFINE_SYSFS_GROUP_VISIBLE(), and then pass that same prefix
> > > to SYSFS_GROUP_VISIBLE() when assigning the @is_visible() callback:
> > >
> > > DEFINE_SYSFS_GROUP_VISIBLE($prefix)
> > >
> > > struct attribute_group $prefix_group = {
> > > .name = $name,
> > > .is_visible = SYSFS_GROUP_VISIBLE($prefix),
> > > };
> > >
> > > SYSFS_GROUP_VISIBLE() expects a definition of $prefix_group_visible()
> > > and $prefix_attr_visible(), where $prefix_group_visible() just returns
> > > true / false and $prefix_attr_visible() behaves as normal.
> > >
> > > The motivation for this capability is to centralize PCI device
> > > authentication in the PCI core with a named sysfs group while keeping
> > > that group hidden for devices and platforms that do not meet the
> > > requirements. In a PCI topology, most devices will not support
> > > authentication, a small subset will support just PCI CMA (Component
> > > Measurement and Authentication), a smaller subset will support PCI CMA +
> > > PCIe IDE (Link Integrity and Encryption), and only next generation
> > > server hosts will start to include a platform TSM (TEE Security
> > > Manager).
> > >
> > > Without this capability the alternatives are:
> > >
> > > * Check if all attributes are invisible and if so, hide the directory.
> > > Beyond trouble getting this to work [1], this is an ABI change for
> > > scenarios if userspace happens to depend on group visibility absent any
> > > attributes. I.e. this new capability avoids regression since it does
> > > not retroactively apply to existing cases.
> > >
> > > * Publish an empty /sys/bus/pci/devices/$pdev/tsm/ directory for all PCI
> > > devices (i.e. for the case when TSM platform support is present, but
> > > device support is absent). Unfortunate that this will be a vestigial
> > > empty directory in the vast majority of cases.
> > >
> > > * Reintroduce usage of runtime calls to sysfs_{create,remove}_group()
> > > in the PCI core. Bjorn has already indicated that he does not want to
> > > see any growth of pci_sysfs_init() [2].
> > >
> > > * Drop the named group and simulate a directory by prefixing all
> > > TSM-related attributes with "tsm_". Unfortunate to not use the naming
> > > capability of a sysfs group as intended.
> > >
> > > In comparison, there is a small potential for regression if for some
> > > reason an @is_visible() callback had dependencies on how many times it
> > > was called. Additionally, it is no longer an error to update a group
> > > that does not have its directory already present, and it is no longer a
> > > WARN() to remove a group that was never visible.
> > >
> > > Link: https://lore.kernel.org/all/2024012321-envious-procedure-4a58@gregkh/ [1]
> > > Link: https://lore.kernel.org/linux-pci/20231019200110.GA1410324@bhelgaas/ [2]
> > > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > This patch seems to introduce a regression on our Lunar Lake test
> > devices, where we can't boot to an ssh shell. No issues on older devices
> > [1]. Bard Liao and I reproduced the same results on different boards.
> >
> > We'll need to find someone with direct device access to provide more
> > information on the problem, remote testing without ssh is a
> > self-negating proposition.
> >
> > Is there a dependency on other patches? Our tests are still based on
> > 6.7.0-rc3 due to other upstream issues we're currently working through.
>
> The only behavior change I can imagine with this patch is that
> ->is_visble() callbacks get called extra times for named attribute
> groups.
>
> ...or if an is_visible() callback was inadvertantly already using the
> SYSFS_GROUP_INVISIBLE flag in umode_t result.
Are you able to get kernel logs? A before and after with this patch
applied might highlight which attribute does not appreciate the extra
callback...
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index ccb275cdabcb..683c0b10990b 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -33,11 +33,17 @@ static void remove_files(struct kernfs_node *parent,
static umode_t __first_visible(const struct attribute_group *grp, struct kobject *kobj)
{
- if (grp->attrs && grp->is_visible)
+ if (grp->attrs && grp->is_visible) {
+ pr_info("kobj: %s is_visible: %pS\n", kobj->name,
+ grp->is_visible);
return grp->is_visible(kobj, grp->attrs[0], 0);
+ }
- if (grp->bin_attrs && grp->is_bin_visible)
+ if (grp->bin_attrs && grp->is_bin_visible) {
+ pr_info("kobj: %s is_bin_visible: %pS\n", kobj->name,
+ grp->is_bin_visible);
return grp->is_bin_visible(kobj, grp->bin_attrs[0], 0);
+ }
return 0;
}
@@ -62,6 +68,8 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
if (update)
kernfs_remove_by_name(parent, (*attr)->name);
if (grp->is_visible) {
+ pr_info("kobj: %s is_visible: %pS\n",
+ kobj->name, grp->is_visible);
mode = grp->is_visible(kobj, *attr, i);
mode &= ~SYSFS_GROUP_INVISIBLE;
if (!mode)
@@ -92,6 +100,8 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
kernfs_remove_by_name(parent,
(*bin_attr)->attr.name);
if (grp->is_bin_visible) {
+ pr_info("kobj: %s is_bin_visible: %pS\n",
+ kobj->name, grp->is_bin_visible);
mode = grp->is_bin_visible(kobj, *bin_attr, i);
mode &= ~SYSFS_GROUP_INVISIBLE;
if (!mode)
@@ -31,6 +31,17 @@ static void remove_files(struct kernfs_node *parent,
kernfs_remove_by_name(parent, (*bin_attr)->attr.name);
}
+static umode_t __first_visible(const struct attribute_group *grp, struct kobject *kobj)
+{
+ if (grp->attrs && grp->is_visible)
+ return grp->is_visible(kobj, grp->attrs[0], 0);
+
+ if (grp->bin_attrs && grp->is_bin_visible)
+ return grp->is_bin_visible(kobj, grp->bin_attrs[0], 0);
+
+ return 0;
+}
+
static int create_files(struct kernfs_node *parent, struct kobject *kobj,
kuid_t uid, kgid_t gid,
const struct attribute_group *grp, int update)
@@ -52,6 +63,7 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
kernfs_remove_by_name(parent, (*attr)->name);
if (grp->is_visible) {
mode = grp->is_visible(kobj, *attr, i);
+ mode &= ~SYSFS_GROUP_INVISIBLE;
if (!mode)
continue;
}
@@ -81,6 +93,7 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
(*bin_attr)->attr.name);
if (grp->is_bin_visible) {
mode = grp->is_bin_visible(kobj, *bin_attr, i);
+ mode &= ~SYSFS_GROUP_INVISIBLE;
if (!mode)
continue;
}
@@ -127,16 +140,31 @@ static int internal_create_group(struct kobject *kobj, int update,
kobject_get_ownership(kobj, &uid, &gid);
if (grp->name) {
+ umode_t mode = __first_visible(grp, kobj);
+
+ if (mode & SYSFS_GROUP_INVISIBLE)
+ mode = 0;
+ else
+ mode = S_IRWXU | S_IRUGO | S_IXUGO;
+
if (update) {
kn = kernfs_find_and_get(kobj->sd, grp->name);
if (!kn) {
- pr_warn("Can't update unknown attr grp name: %s/%s\n",
- kobj->name, grp->name);
- return -EINVAL;
+ pr_debug("attr grp %s/%s not created yet\n",
+ kobj->name, grp->name);
+ /* may have been invisible prior to this update */
+ update = 0;
+ } else if (!mode) {
+ sysfs_remove_group(kobj, grp);
+ kernfs_put(kn);
+ return 0;
}
- } else {
- kn = kernfs_create_dir_ns(kobj->sd, grp->name,
- S_IRWXU | S_IRUGO | S_IXUGO,
+ }
+
+ if (!update) {
+ if (!mode)
+ return 0;
+ kn = kernfs_create_dir_ns(kobj->sd, grp->name, mode,
uid, gid, kobj, NULL);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
@@ -279,9 +307,8 @@ void sysfs_remove_group(struct kobject *kobj,
if (grp->name) {
kn = kernfs_find_and_get(parent, grp->name);
if (!kn) {
- WARN(!kn, KERN_WARNING
- "sysfs group '%s' not found for kobject '%s'\n",
- grp->name, kobject_name(kobj));
+ pr_debug("sysfs group '%s' not found for kobject '%s'\n",
+ grp->name, kobject_name(kobj));
return;
}
} else {
@@ -61,22 +61,32 @@ do { \
/**
* struct attribute_group - data structure used to declare an attribute group.
* @name: Optional: Attribute group name
- * If specified, the attribute group will be created in
- * a new subdirectory with this name.
+ * If specified, the attribute group will be created in a
+ * new subdirectory with this name. Additionally when a
+ * group is named, @is_visible and @is_bin_visible may
+ * return SYSFS_GROUP_INVISIBLE to control visibility of
+ * the directory itself.
* @is_visible: Optional: Function to return permissions associated with an
- * attribute of the group. Will be called repeatedly for each
- * non-binary attribute in the group. Only read/write
+ * attribute of the group. Will be called repeatedly for
+ * each non-binary attribute in the group. Only read/write
* permissions as well as SYSFS_PREALLOC are accepted. Must
- * return 0 if an attribute is not visible. The returned value
- * will replace static permissions defined in struct attribute.
+ * return 0 if an attribute is not visible. The returned
+ * value will replace static permissions defined in struct
+ * attribute. Use SYSFS_GROUP_VISIBLE() when assigning this
+ * callback to specify separate _group_visible() and
+ * _attr_visible() handlers.
* @is_bin_visible:
* Optional: Function to return permissions associated with a
* binary attribute of the group. Will be called repeatedly
* for each binary attribute in the group. Only read/write
- * permissions as well as SYSFS_PREALLOC are accepted. Must
- * return 0 if a binary attribute is not visible. The returned
- * value will replace static permissions defined in
- * struct bin_attribute.
+ * permissions as well as SYSFS_PREALLOC (and the
+ * visibility flags for named groups) are accepted. Must
+ * return 0 if a binary attribute is not visible. The
+ * returned value will replace static permissions defined
+ * in struct bin_attribute. If @is_visible is not set, Use
+ * SYSFS_GROUP_VISIBLE() when assigning this callback to
+ * specify separate _group_visible() and _attr_visible()
+ * handlers.
* @attrs: Pointer to NULL terminated list of attributes.
* @bin_attrs: Pointer to NULL terminated list of binary attributes.
* Either attrs or bin_attrs or both must be provided.
@@ -91,13 +101,42 @@ struct attribute_group {
struct bin_attribute **bin_attrs;
};
+#define SYSFS_PREALLOC 010000
+#define SYSFS_GROUP_INVISIBLE 020000
+
+/*
+ * The first call to is_visible() in the create / update path may
+ * indicate visibility for the entire group
+ */
+#define DEFINE_SYSFS_GROUP_VISIBLE(name) \
+ static inline umode_t sysfs_group_visible_##name( \
+ struct kobject *kobj, struct attribute *attr, int n) \
+ { \
+ if (n == 0 && !name##_group_visible(kobj)) \
+ return SYSFS_GROUP_INVISIBLE; \
+ return name##_attr_visible(kobj, attr, n); \
+ }
+
+/*
+ * Same as DEFINE_SYSFS_GROUP_VISIBLE, but for groups with only binary
+ * attributes
+ */
+#define DEFINE_SYSFS_BIN_GROUP_VISIBLE(name) \
+ static inline umode_t sysfs_group_visible_##name( \
+ struct kobject *kobj, struct bin_attribute *attr, int n) \
+ { \
+ if (n == 0 && !name##_group_visible(kobj)) \
+ return SYSFS_GROUP_INVISIBLE; \
+ return name##_attr_visible(kobj, attr, n); \
+ }
+
+#define SYSFS_GROUP_VISIBLE(fn) sysfs_group_visible_##fn
+
/*
* Use these macros to make defining attributes easier.
* See include/linux/device.h for examples..
*/
-#define SYSFS_PREALLOC 010000
-
#define __ATTR(_name, _mode, _show, _store) { \
.attr = {.name = __stringify(_name), \
.mode = VERIFY_OCTAL_PERMISSIONS(_mode) }, \