uio_hv_generic: Fix ring buffer sysfs creation path

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.

* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

From: Naman Jain <[email protected]> Sent: Wednesday, April 23, 2025 10:35 PM

Quoted 9 lines

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Quoted 7 lines

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.

Ah, OK :-) I thought you had decided to leave the test in, and I wasn't going to argue further, as it didn't hurt anything. But the test is superfluous, so the code is better without it. It won't mislead a future someone into thinking that it solves a synchronization problem.

Michael

Quoted 7 lines

* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.
* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

Quoted 8 lines · Naman Jain

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Quoted 12 lines

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.
* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

Please fix up to apply cleanly without build warnings:

drivers/hv/vmbus_drv.c:1893:15: error: initializing 'struct bin_attribute **' with an expression of type 'const struct bin_attribute *const[2]' discards qualifiers in nested pointer types [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
1893 | .bin_attrs = vmbus_chan_bin_attrs,

       |                      ^~~~~~~~~~~~~~~~~~~~

1 error generated.

Quoted 22 lines · Greg Kroah-Hartman

Quoted 8 lines · Naman Jain

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Quoted 12 lines

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.
* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

Quoted 6 lines

Please fix up to apply cleanly without build warnings:

drivers/hv/vmbus_drv.c:1893:15: error: initializing 'struct bin_attribute **' with an expression of type 'const struct bin_attribute *const[2]' discards qualifiers in nested pointer types [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
1893 | .bin_attrs = vmbus_chan_bin_attrs,

       |                      ^~~~~~~~~~~~~~~~~~~~

1 error generated.

Hi Greg,
I tried reproducing this error but could not see it. Should I rebase the change to some other tree or use some specific config option, gcc version, compilation flag etc.?

I tried the following:
* Rebased to latest linux-next tip with below base commit:
393d0c54cae31317deaa9043320c5fd9454deabc
* Regular compilation with gcc: make -j8
* extra flags:
make -j8 EXTRA_CFLAGS="-Wall -O2"
make -j8 EXTRA_CFLAGS="-Wincompatible-pointer-types-discards-qualifiers
-Werror"
* Tried gcc 11.4, 13.3
* Tried clang/LLVM with version 18.1.3 : make LLVM=1

BTW I had to edit the type for bin_attrs as this change got merged recently:
9bec944506fa ("sysfs: constify attribute_group::bin_attrs")

include/linux/sysfs.h +0 -0

index 576b8b3c60af..f418aae4f113 100644

Quoted 37 lines · Naman Jain

Quoted 22 lines · Greg Kroah-Hartman

Quoted 8 lines · Naman Jain

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Quoted 12 lines

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.
* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

Quoted 6 lines

Please fix up to apply cleanly without build warnings:

drivers/hv/vmbus_drv.c:1893:15: error: initializing 'struct bin_attribute **' with an expression of type 'const struct bin_attribute *const[2]' discards qualifiers in nested pointer types [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
1893 | .bin_attrs = vmbus_chan_bin_attrs,

        |                      ^~~~~~~~~~~~~~~~~~~~

1 error generated.

Hi Greg,
I tried reproducing this error but could not see it. Should I rebase the change to some other tree or use some specific config option, gcc version, compilation flag etc.?

Quoted 10 lines

I tried the following:
* Rebased to latest linux-next tip with below base commit:
393d0c54cae31317deaa9043320c5fd9454deabc
* Regular compilation with gcc: make -j8
* extra flags:
make -j8 EXTRA_CFLAGS="-Wall -O2"
make -j8 EXTRA_CFLAGS="-Wincompatible-pointer-types-discards-qualifiers
-Werror"
* Tried gcc 11.4, 13.3
* Tried clang/LLVM with version 18.1.3 : make LLVM=1

I tried this against my char-misc-linus branch (which is pretty much just 6.15.0-rc4 plus some iio patches), and it fails with that error above.

Quoted 8 lines

BTW I had to edit the type for bin_attrs as this change got merged recently:
9bec944506fa ("sysfs: constify attribute_group::bin_attrs")

include/linux/sysfs.h +0 -0

index 576b8b3c60af..f418aae4f113 100644

include/linux/sysfs.h struct attribute_group { · line 113

Quoted 8 lines

include/linux/sysfs.h +1 -1

@@ -107,7 +107,7 @@ struct attribute_group {
                                             int);
         struct attribute        **attrs;
         union {
-               struct bin_attribute            **bin_attrs;
+               const struct bin_attribute      *const *bin_attrs;
                 const struct bin_attribute      *const *bin_attrs_new;
         };
  };

That commit is not in my char-misc branches, that's coming from somewhere else.

thanks,

greg k-h

Quoted 75 lines · Greg Kroah-Hartman

Quoted 37 lines · Naman Jain

Quoted 22 lines · Greg Kroah-Hartman

Quoted 8 lines · Naman Jain

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Quoted 12 lines

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.
* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

Quoted 6 lines

Please fix up to apply cleanly without build warnings:

drivers/hv/vmbus_drv.c:1893:15: error: initializing 'struct bin_attribute **' with an expression of type 'const struct bin_attribute *const[2]' discards qualifiers in nested pointer types [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
1893 | .bin_attrs = vmbus_chan_bin_attrs,

        |                      ^~~~~~~~~~~~~~~~~~~~

1 error generated.

Hi Greg,
I tried reproducing this error but could not see it. Should I rebase the change to some other tree or use some specific config option, gcc version, compilation flag etc.?

Quoted 10 lines

I tried the following:
* Rebased to latest linux-next tip with below base commit:
393d0c54cae31317deaa9043320c5fd9454deabc
* Regular compilation with gcc: make -j8
* extra flags:
make -j8 EXTRA_CFLAGS="-Wall -O2"
make -j8 EXTRA_CFLAGS="-Wincompatible-pointer-types-discards-qualifiers
-Werror"
* Tried gcc 11.4, 13.3
* Tried clang/LLVM with version 18.1.3 : make LLVM=1

I tried this against my char-misc-linus branch (which is pretty much just 6.15.0-rc4 plus some iio patches), and it fails with that error above.

Quoted 8 lines

BTW I had to edit the type for bin_attrs as this change got merged recently:
9bec944506fa ("sysfs: constify attribute_group::bin_attrs")

include/linux/sysfs.h +0 -0

index 576b8b3c60af..f418aae4f113 100644

include/linux/sysfs.h struct attribute_group { · line 113

Quoted 8 lines

include/linux/sysfs.h +1 -1

@@ -107,7 +107,7 @@ struct attribute_group {
                                             int);
         struct attribute        **attrs;
         union {
-               struct bin_attribute            **bin_attrs;
+               const struct bin_attribute      *const *bin_attrs;
                 const struct bin_attribute      *const *bin_attrs_new;
         };
  };

That commit is not in my char-misc branches, that's coming from somewhere else.

thanks,

Quoted 1 line

greg k-h

Hi Greg,

I can send a patch based on char-misc/6.15.0-rc4 which does not have this patch, but I am worried that it will cause compilation issues when your branch is merged with linux-next since this change is already there in linux-next. Do you want me to proceed with sending a patch on 6.15.0-rc4?

Here are more details of that patch:

"""
sysfs: constify attribute_group::bin_attrs
All users of this field have been migrated to bin_attrs_new. It can now be constified.

Signed-off-by Thomas Weißschuh <[email protected]>

Link https://lore.kernel.org/r/20250313-sysfs-const-bin_attr-final-v2-2-96284e1e88ce@weissschuh.net open here

Signed-off-by Greg Kroah-Hartman <[email protected]>

"""

Quoted 78 lines · Naman Jain

Quoted 75 lines · Greg Kroah-Hartman

Quoted 37 lines · Naman Jain

Quoted 22 lines · Greg Kroah-Hartman

Quoted 8 lines · Naman Jain

Hi,
This patch series aims to address the sysfs creation issue for the ring buffer by reorganizing the code. Additionally, it updates the ring sysfs size to accurately reflect the actual ring buffer size, rather than a fixed static value.

PFB change logs:

Quoted 12 lines

Changes since v5:
https://lore.kernel.org/all/[email protected]/
* Added Reviewed-By tags from Dexuan. Also, addressed minor comments in commit msg of both patches.
* Missed to remove check for "primary_channel->device_obj->channels_kset" in hv_create_ring_sysfs in earlier patch, as suggested by Michael. Did it now.
* Changed type for declaring bin_attrs due to changes introduced by commit 9bec944506fa ("sysfs: constify attribute_group::bin_attrs") which merged recently. Did not use bin_attrs_new since another change is in the queue to change usage of bin_attrs_new to bin_attrs (sysfs: finalize the constification of 'struct bin_attribute').

Quoted 6 lines

Please fix up to apply cleanly without build warnings:

drivers/hv/vmbus_drv.c:1893:15: error: initializing 'struct bin_attribute **' with an expression of type 'const struct bin_attribute *const[2]' discards qualifiers in nested pointer types [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
1893 | .bin_attrs = vmbus_chan_bin_attrs,
| ^~~~~~~~~~~~~~~~~~~~
1 error generated.

Hi Greg,
I tried reproducing this error but could not see it. Should I rebase the change to some other tree or use some specific config option, gcc version, compilation flag etc.?

Quoted 10 lines

I tried the following:
* Rebased to latest linux-next tip with below base commit:
393d0c54cae31317deaa9043320c5fd9454deabc
* Regular compilation with gcc: make -j8
* extra flags:
make -j8 EXTRA_CFLAGS="-Wall -O2"
make -j8 EXTRA_CFLAGS="-Wincompatible-pointer-types-discards-qualifiers
-Werror"
* Tried gcc 11.4, 13.3
* Tried clang/LLVM with version 18.1.3 : make LLVM=1

I tried this against my char-misc-linus branch (which is pretty much just 6.15.0-rc4 plus some iio patches), and it fails with that error above.

Quoted 8 lines

BTW I had to edit the type for bin_attrs as this change got merged recently:
9bec944506fa ("sysfs: constify attribute_group::bin_attrs")

include/linux/sysfs.h +0 -0

index 576b8b3c60af..f418aae4f113 100644

include/linux/sysfs.h struct attribute_group { · line 113

Quoted 8 lines

include/linux/sysfs.h +1 -1

@@ -107,7 +107,7 @@ struct attribute_group {
                                              int);
          struct attribute        **attrs;
          union {
-               struct bin_attribute            **bin_attrs;
+               const struct bin_attribute      *const *bin_attrs;
                  const struct bin_attribute      *const *bin_attrs_new;
          };
   };

That commit is not in my char-misc branches, that's coming from somewhere else.

thanks,

Quoted 8 lines

Quoted 1 line

greg k-h

Hi Greg,

I can send a patch based on char-misc/6.15.0-rc4 which does not have this patch, but I am worried that it will cause compilation issues when your branch is merged with linux-next since this change is already there in linux-next. Do you want me to proceed with sending a patch on 6.15.0-rc4?

Yes, because you want this fix in 6.15-final, right?

Quoted 7 lines

Here are more details of that patch:

"""
sysfs: constify attribute_group::bin_attrs
All users of this field have been migrated to bin_attrs_new. It can now be constified.

Quoted 5 lines

Signed-off-by Thomas Weißschuh <[email protected]>

Link https://lore.kernel.org/r/20250313-sysfs-const-bin_attr-final-v2-2-96284e1e88ce@weissschuh.net open here

Signed-off-by Greg Kroah-Hartman <[email protected]>

"""

I know that patch, I will deal with that in linux-next when needed, you shouldn't be worrying about it. I'm more concerned as to why your patch was not being tested against Linus's tree if you expected it to be in the latest release and backported everywhere as it you asked it to be.

thanks,

greg k-h