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[PATCH v3 07/16] rust: block: use `NullTerminatedFormatter`

Andreas Hindborg posted 16 patches 2 months, 3 weeks ago
There is a newer version of this series
[PATCH v3 07/16] rust: block: use `NullTerminatedFormatter`
Posted by Andreas Hindborg 2 months, 3 weeks ago 
Use the new `NullTerminatedFormatter` to write the name of a `GenDisk` to
the name buffer. This new formatter automatically adds a trailing null
marker after the written characters, so we don't need to append that at the
call site any longer.

Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
 rust/kernel/block/mq/gen_disk.rs   | 11 ++++++-----
 rust/kernel/block/mq/raw_writer.rs |  1 +
 rust/kernel/str.rs                 |  1 -
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs
index 679ee1bb2195..39be2a31337f 100644
--- a/rust/kernel/block/mq/gen_disk.rs
+++ b/rust/kernel/block/mq/gen_disk.rs
@@ -7,9 +7,10 @@
 
 use crate::{
     bindings,
-    block::mq::{raw_writer::RawWriter, Operations, TagSet},
+    block::mq::{Operations, TagSet},
     error::{self, from_err_ptr, Result},
     static_lock_class,
+    str::NullTerminatedFormatter,
     sync::Arc,
 };
 use core::fmt::{self, Write};
@@ -143,14 +144,14 @@ pub fn build<T: Operations>(
         // SAFETY: `gendisk` is a valid pointer as we initialized it above
         unsafe { (*gendisk).fops = &TABLE };
 
-        let mut raw_writer = RawWriter::from_array(
+        let mut writer = NullTerminatedFormatter::from_array(
             // SAFETY: `gendisk` points to a valid and initialized instance. We
             // have exclusive access, since the disk is not added to the VFS
             // yet.
             unsafe { &mut (*gendisk).disk_name },
-        )?;
-        raw_writer.write_fmt(name)?;
-        raw_writer.write_char('\0')?;
+        )
+        .ok_or(error::code::EINVAL)?;
+        writer.write_fmt(name)?;
 
         // SAFETY: `gendisk` points to a valid and initialized instance of
         // `struct gendisk`. `set_capacity` takes a lock to synchronize this
diff --git a/rust/kernel/block/mq/raw_writer.rs b/rust/kernel/block/mq/raw_writer.rs
index 7e2159e4f6a6..0aef55703e71 100644
--- a/rust/kernel/block/mq/raw_writer.rs
+++ b/rust/kernel/block/mq/raw_writer.rs
@@ -24,6 +24,7 @@ fn new(buffer: &'a mut [u8]) -> Result<RawWriter<'a>> {
         Ok(Self { buffer, pos: 0 })
     }
 
+    #[expect(dead_code)]
     pub(crate) fn from_array<const N: usize>(
         a: &'a mut [crate::ffi::c_char; N],
     ) -> Result<RawWriter<'a>> {
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index c58925438c6e..7396c49174cd 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -858,7 +858,6 @@ pub(crate) fn new(buffer: &'a mut [u8]) -> Option<NullTerminatedFormatter<'a>> {
         Some(Self { buffer })
     }
 
-    #[expect(dead_code)]
     pub(crate) fn from_array<const N: usize>(
         buffer: &'a mut [crate::ffi::c_char; N],
     ) -> Option<NullTerminatedFormatter<'a>> {

-- 
2.47.2
Re: [PATCH v3 07/16] rust: block: use `NullTerminatedFormatter`
Posted by Daniel Almeida 2 months ago 
Hi Andreas,

> On 11 Jul 2025, at 08:43, Andreas Hindborg <a.hindborg@kernel.org> wrote:
> 
> Use the new `NullTerminatedFormatter` to write the name of a `GenDisk` to
> the name buffer. This new formatter automatically adds a trailing null
> marker after the written characters, so we don't need to append that at the
> call site any longer.
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
> ---
> rust/kernel/block/mq/gen_disk.rs   | 11 ++++++-----
> rust/kernel/block/mq/raw_writer.rs |  1 +
> rust/kernel/str.rs                 |  1 -
> 3 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs
> index 679ee1bb2195..39be2a31337f 100644
> --- a/rust/kernel/block/mq/gen_disk.rs
> +++ b/rust/kernel/block/mq/gen_disk.rs
> @@ -7,9 +7,10 @@
> 
> use crate::{
>     bindings,
> -    block::mq::{raw_writer::RawWriter, Operations, TagSet},
> +    block::mq::{Operations, TagSet},
>     error::{self, from_err_ptr, Result},
>     static_lock_class,
> +    str::NullTerminatedFormatter,
>     sync::Arc,
> };
> use core::fmt::{self, Write};
> @@ -143,14 +144,14 @@ pub fn build<T: Operations>(
>         // SAFETY: `gendisk` is a valid pointer as we initialized it above
>         unsafe { (*gendisk).fops = &TABLE };
> 
> -        let mut raw_writer = RawWriter::from_array(
> +        let mut writer = NullTerminatedFormatter::from_array(
>             // SAFETY: `gendisk` points to a valid and initialized instance. We
>             // have exclusive access, since the disk is not added to the VFS
>             // yet.
>             unsafe { &mut (*gendisk).disk_name },
> -        )?;
> -        raw_writer.write_fmt(name)?;
> -        raw_writer.write_char('\0')?;
> +        )
> +        .ok_or(error::code::EINVAL)?;
> +        writer.write_fmt(name)?;
> 
>         // SAFETY: `gendisk` points to a valid and initialized instance of
>         // `struct gendisk`. `set_capacity` takes a lock to synchronize this
> diff --git a/rust/kernel/block/mq/raw_writer.rs b/rust/kernel/block/mq/raw_writer.rs
> index 7e2159e4f6a6..0aef55703e71 100644
> --- a/rust/kernel/block/mq/raw_writer.rs
> +++ b/rust/kernel/block/mq/raw_writer.rs
> @@ -24,6 +24,7 @@ fn new(buffer: &'a mut [u8]) -> Result<RawWriter<'a>> {
>         Ok(Self { buffer, pos: 0 })
>     }
> 
> +    #[expect(dead_code)]

Not sure I understand, is this superseded by..

>     pub(crate) fn from_array<const N: usize>(
>         a: &'a mut [crate::ffi::c_char; N],
>     ) -> Result<RawWriter<'a>> {
> diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
> index c58925438c6e..7396c49174cd 100644
> --- a/rust/kernel/str.rs
> +++ b/rust/kernel/str.rs
> @@ -858,7 +858,6 @@ pub(crate) fn new(buffer: &'a mut [u8]) -> Option<NullTerminatedFormatter<'a>> {
>         Some(Self { buffer })
>     }
> 
> -    #[expect(dead_code)]

… this?

>     pub(crate) fn from_array<const N: usize>(
>         buffer: &'a mut [crate::ffi::c_char; N],
>     ) -> Option<NullTerminatedFormatter<'a>> {
> 
> -- 
> 2.47.2
> 
> 
> 

— Daniel
Re: [PATCH v3 07/16] rust: block: use `NullTerminatedFormatter`
Posted by Andreas Hindborg 2 months ago 
"Daniel Almeida" <daniel.almeida@collabora.com> writes:

> Hi Andreas,
>
>> On 11 Jul 2025, at 08:43, Andreas Hindborg <a.hindborg@kernel.org> wrote:
>>
>> Use the new `NullTerminatedFormatter` to write the name of a `GenDisk` to
>> the name buffer. This new formatter automatically adds a trailing null
>> marker after the written characters, so we don't need to append that at the
>> call site any longer.
>>
>> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
>> ---
>> rust/kernel/block/mq/gen_disk.rs   | 11 ++++++-----
>> rust/kernel/block/mq/raw_writer.rs |  1 +
>> rust/kernel/str.rs                 |  1 -
>> 3 files changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs
>> index 679ee1bb2195..39be2a31337f 100644
>> --- a/rust/kernel/block/mq/gen_disk.rs
>> +++ b/rust/kernel/block/mq/gen_disk.rs
>> @@ -7,9 +7,10 @@
>>
>> use crate::{
>>     bindings,
>> -    block::mq::{raw_writer::RawWriter, Operations, TagSet},
>> +    block::mq::{Operations, TagSet},
>>     error::{self, from_err_ptr, Result},
>>     static_lock_class,
>> +    str::NullTerminatedFormatter,
>>     sync::Arc,
>> };
>> use core::fmt::{self, Write};
>> @@ -143,14 +144,14 @@ pub fn build<T: Operations>(
>>         // SAFETY: `gendisk` is a valid pointer as we initialized it above
>>         unsafe { (*gendisk).fops = &TABLE };
>>
>> -        let mut raw_writer = RawWriter::from_array(
>> +        let mut writer = NullTerminatedFormatter::from_array(
>>             // SAFETY: `gendisk` points to a valid and initialized instance. We
>>             // have exclusive access, since the disk is not added to the VFS
>>             // yet.
>>             unsafe { &mut (*gendisk).disk_name },
>> -        )?;
>> -        raw_writer.write_fmt(name)?;
>> -        raw_writer.write_char('\0')?;
>> +        )
>> +        .ok_or(error::code::EINVAL)?;
>> +        writer.write_fmt(name)?;
>>
>>         // SAFETY: `gendisk` points to a valid and initialized instance of
>>         // `struct gendisk`. `set_capacity` takes a lock to synchronize this
>> diff --git a/rust/kernel/block/mq/raw_writer.rs b/rust/kernel/block/mq/raw_writer.rs
>> index 7e2159e4f6a6..0aef55703e71 100644
>> --- a/rust/kernel/block/mq/raw_writer.rs
>> +++ b/rust/kernel/block/mq/raw_writer.rs
>> @@ -24,6 +24,7 @@ fn new(buffer: &'a mut [u8]) -> Result<RawWriter<'a>> {
>>         Ok(Self { buffer, pos: 0 })
>>     }
>>
>> +    #[expect(dead_code)]
>
> Not sure I understand, is this superseded by..
>
>>     pub(crate) fn from_array<const N: usize>(
>>         a: &'a mut [crate::ffi::c_char; N],
>>     ) -> Result<RawWriter<'a>> {
>> diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
>> index c58925438c6e..7396c49174cd 100644
>> --- a/rust/kernel/str.rs
>> +++ b/rust/kernel/str.rs
>> @@ -858,7 +858,6 @@ pub(crate) fn new(buffer: &'a mut [u8]) -> Option<NullTerminatedFormatter<'a>> {
>>         Some(Self { buffer })
>>     }
>>
>> -    #[expect(dead_code)]
>
> … this?
>
>>     pub(crate) fn from_array<const N: usize>(
>>         buffer: &'a mut [crate::ffi::c_char; N],
>>     ) -> Option<NullTerminatedFormatter<'a>> {
>>

Yes. Alice suggested combining patch 8/16 that removes
`block::mq::raw_writer` with this one.


Best regards,
Andreas Hindborg
Re: [PATCH v3 07/16] rust: block: use `NullTerminatedFormatter`
Posted by Daniel Almeida 2 months ago 

> On 6 Aug 2025, at 10:22, Daniel Almeida <daniel.almeida@collabora.com> wrote:
> 
> Hi Andreas,
> 
>> On 11 Jul 2025, at 08:43, Andreas Hindborg <a.hindborg@kernel.org> wrote:
>> 
>> Use the new `NullTerminatedFormatter` to write the name of a `GenDisk` to
>> the name buffer. This new formatter automatically adds a trailing null
>> marker after the written characters, so we don't need to append that at the
>> call site any longer.
>> 
>> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
>> ---
>> rust/kernel/block/mq/gen_disk.rs   | 11 ++++++-----
>> rust/kernel/block/mq/raw_writer.rs |  1 +
>> rust/kernel/str.rs                 |  1 -
>> 3 files changed, 7 insertions(+), 6 deletions(-)
>> 
>> diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs
>> index 679ee1bb2195..39be2a31337f 100644
>> --- a/rust/kernel/block/mq/gen_disk.rs
>> +++ b/rust/kernel/block/mq/gen_disk.rs
>> @@ -7,9 +7,10 @@
>> 
>> use crate::{
>>    bindings,
>> -    block::mq::{raw_writer::RawWriter, Operations, TagSet},
>> +    block::mq::{Operations, TagSet},
>>    error::{self, from_err_ptr, Result},
>>    static_lock_class,
>> +    str::NullTerminatedFormatter,
>>    sync::Arc,
>> };
>> use core::fmt::{self, Write};
>> @@ -143,14 +144,14 @@ pub fn build<T: Operations>(
>>        // SAFETY: `gendisk` is a valid pointer as we initialized it above
>>        unsafe { (*gendisk).fops = &TABLE };
>> 
>> -        let mut raw_writer = RawWriter::from_array(
>> +        let mut writer = NullTerminatedFormatter::from_array(
>>            // SAFETY: `gendisk` points to a valid and initialized instance. We
>>            // have exclusive access, since the disk is not added to the VFS
>>            // yet.
>>            unsafe { &mut (*gendisk).disk_name },
>> -        )?;
>> -        raw_writer.write_fmt(name)?;
>> -        raw_writer.write_char('\0')?;
>> +        )
>> +        .ok_or(error::code::EINVAL)?;
>> +        writer.write_fmt(name)?;
>> 
>>        // SAFETY: `gendisk` points to a valid and initialized instance of
>>        // `struct gendisk`. `set_capacity` takes a lock to synchronize this
>> diff --git a/rust/kernel/block/mq/raw_writer.rs b/rust/kernel/block/mq/raw_writer.rs
>> index 7e2159e4f6a6..0aef55703e71 100644
>> --- a/rust/kernel/block/mq/raw_writer.rs
>> +++ b/rust/kernel/block/mq/raw_writer.rs
>> @@ -24,6 +24,7 @@ fn new(buffer: &'a mut [u8]) -> Result<RawWriter<'a>> {
>>        Ok(Self { buffer, pos: 0 })
>>    }
>> 
>> +    #[expect(dead_code)]
> 
> Not sure I understand, is this superseded by..
> 
>>    pub(crate) fn from_array<const N: usize>(
>>        a: &'a mut [crate::ffi::c_char; N],
>>    ) -> Result<RawWriter<'a>> {
>> diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
>> index c58925438c6e..7396c49174cd 100644
>> --- a/rust/kernel/str.rs
>> +++ b/rust/kernel/str.rs
>> @@ -858,7 +858,6 @@ pub(crate) fn new(buffer: &'a mut [u8]) -> Option<NullTerminatedFormatter<'a>> {
>>        Some(Self { buffer })
>>    }
>> 
>> -    #[expect(dead_code)]
> 
> … this?
> 
>>    pub(crate) fn from_array<const N: usize>(
>>        buffer: &'a mut [crate::ffi::c_char; N],
>>    ) -> Option<NullTerminatedFormatter<'a>> {
>> 
>> -- 
>> 2.47.2
>> 
>> 
>> 
> 
> — Daniel

Ah, I just saw the next patch.

Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Re: [PATCH v3 07/16] rust: block: use `NullTerminatedFormatter`
Posted by Alice Ryhl 2 months, 3 weeks ago 
On Fri, Jul 11, 2025 at 01:43:08PM +0200, Andreas Hindborg wrote:
> Use the new `NullTerminatedFormatter` to write the name of a `GenDisk` to
> the name buffer. This new formatter automatically adds a trailing null
> marker after the written characters, so we don't need to append that at the
> call site any longer.
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

Patchew 2.1-devel-b67e4c2

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